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Dick DW, Childs L, Feng Z, Li J, Röst G, Buckeridge DL, Ogden NH, Heffernan JM. COVID-19 Seroprevalence in Canada Modelling Waning and Boosting COVID-19 Immunity in Canada a Canadian Immunization Research Network Study. Vaccines (Basel) 2021; 10:17. [PMID: 35062678 PMCID: PMC8779812 DOI: 10.3390/vaccines10010017] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 10/23/2021] [Accepted: 11/24/2021] [Indexed: 11/16/2022] Open
Abstract
COVID-19 seroprevalence changes over time, with infection, vaccination, and waning immunity. Seroprevalence estimates are needed to determine when increased COVID-19 vaccination coverage is needed, and when booster doses should be considered, to reduce the spread and disease severity of COVID-19 infection. We use an age-structured model including infection, vaccination and waning immunity to estimate the distribution of immunity to COVID-19 in the Canadian population. This is the first mathematical model to do so. We estimate that 60-80% of the Canadian population has some immunity to COVID-19 by late Summer 2021, depending on specific characteristics of the vaccine and the waning rate of immunity. Models results indicate that increased vaccination uptake in age groups 12-29, and booster doses in age group 50+ are needed to reduce the severity COVID-19 Fall 2021 resurgence.
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Affiliation(s)
- David W. Dick
- Mathematics and Statistics, Centre for Disease Modelling, York University, Toronto, ON M3J 1P3, Canada;
| | - Lauren Childs
- Department of Mathematics, Virginia Tech, Blacksburg, VA 24061, USA;
| | - Zhilan Feng
- Department of Mathematics, Purdue University, West Lafayette, IN 46202, USA;
- National Science Foundation, Alexandria, VA 22314, USA
| | - Jing Li
- Department of Mathematics, California State University, Northridge, CA 91330, USA;
| | - Gergely Röst
- Department of Mathematics, University of Szeged, 6720 Szeged, Hungary;
| | - David L. Buckeridge
- Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montreal, QC H3A 0G4, Canada;
| | - Nick H. Ogden
- National Microbiology Laboratory, Public Health Risk Sciences Division, Public Health Agency of Canada, St. Hyacinthe, QC J2S 2M2, Canada;
| | - Jane M. Heffernan
- Mathematics and Statistics, Centre for Disease Modelling, York University, Toronto, ON M3J 1P3, Canada;
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2
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Mechai S, Bilodeau G, Lung O, Roy M, Steeves R, Gagne N, Baird D, Lapen DR, Ludwig A, Ogden NH. Mosquito Identification From Bulk Samples Using DNA Metabarcoding: a Protocol to Support Mosquito-Borne Disease Surveillance in Canada. J Med Entomol 2021; 58:1686-1700. [PMID: 33822118 DOI: 10.1093/jme/tjab046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Indexed: 06/12/2023]
Abstract
Approximately 80 species of mosquitoes (Diptera: Culicidae) have been documented in Canada. Exotic species such as Aedes albopictus (Skuse) (Diptera: Culicidae) are becoming established. Recently occurring endemic mosquito-borne diseases (MBD) in Canada including West-Nile virus (WNV) and Eastern Equine Encephalitis (EEE) are having significant public health impacts. Here we explore the use of DNA metabarcoding to identify mosquitoes from CDC light-trap collections from two locations in eastern Canada. Two primer pairs (BF2-BR2 and F230) were used to amplify regions of the cytochrome c oxidase subunit I (CO1) gene. High throughput sequencing was conducted using an Illumina MiSeq platform and GenBank-based species identification was applied using a QIIME 1.9 bioinformatics pipeline. From a site in southeastern Ontario, Canada, 26 CDC light trap collections of 72 to >300 individual mosquitoes were used to explore the capacity of DNA metabarcoding to identify and quantify captured mosquitoes. The DNA metabarcoding method identified 33 species overall while 24 species were identified by key. Using replicates from each trap, the dried biomass needed to identify the majority of species was determined to be 76 mg (equivalent to approximately 72 mosquitoes), and at least two replicates from the dried biomass would be needed to reliably detect the majority of species in collections of 144-215 mosquitoes and three replicates would be advised for collections with >215 mosquitoes. This study supports the use of DNA metabarcoding as a mosquito surveillance tool in Canada which can help identify the emergence of new mosquito-borne disease potential threats.
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Affiliation(s)
- S Mechai
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
| | - G Bilodeau
- Ottawa Plant Laboratory, Canadian Food Inspection Agency, Ottawa, Ontario, Canada
| | - O Lung
- National Centre for Foreign Animal Disease, Canadian Food Inspection Agency, Winnipeg, Manitoba, Canada
| | - M Roy
- Aquatic Animal Health Section, Fisheries & Oceans Canada, Moncton, New Brunswick, Canada
| | - R Steeves
- Aquatic Animal Health Section, Fisheries & Oceans Canada, Moncton, New Brunswick, Canada
| | - N Gagne
- Aquatic Animal Health Section, Fisheries & Oceans Canada, Moncton, New Brunswick, Canada
| | - D Baird
- Environment and Climate Change Canada, Canadian Rivers Institute, Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - D R Lapen
- Ottawa Research Development Centre, Agriculture & Agri-Food Canada, Ottawa, Ontario, Canada
| | - A Ludwig
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
| | - N H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, Canada
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Taieb L, Ludwig A, Ogden NH, Lindsay RL, Iranpour M, Gagnon CA, Bicout DJ. Bird Species Involved in West Nile Virus Epidemiological Cycle in Southern Québec. Int J Environ Res Public Health 2020; 17:ijerph17124517. [PMID: 32585999 PMCID: PMC7344584 DOI: 10.3390/ijerph17124517] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/18/2020] [Accepted: 06/18/2020] [Indexed: 12/03/2022]
Abstract
Despite many studies on West Nile Virus (WNV) in the US, including the reservoir role of bird species and the summer shifts of the Culex mosquito, feeding from birds to mammals, there have been few equivalent studies in the neighboring regions of Canada where WNV is endemic. Here, a priority list of bird species likely involved in WNV transmission in the greater Montréal area is constructed by combining three sources of data: (i) from WNV surveillance in wild birds (2002–2015); (ii) blood meal analysis of Culex pipiens–restuans (CPR), the primary enzootic vectors of WNV in the region, collected from surveillance in 2008 and 2014; (iii) literature review on the sero-prevalence/host competence of resident birds. Each of these data sources yielded 18, 23 and 53 species, and overall, 67 different bird species were identified as potential WNV amplifiers/reservoirs. Of those identified from CPR blood meals, Common starlings, American robins, Song sparrows and House sparrows ranked the highest and blood meal analysis demonstrated a seasonal shift in feed preference from birds to mammals by CPR. Our study indicates that there are broad similarities in the ecology of WNV between our region and the northeastern US, although the relative importance of bird species varies somewhat between regions.
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Affiliation(s)
- Ludivine Taieb
- Research Group on Epidemiology of Zoonoses and Public Health (GREZOSP), Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada; (L.T.); (N.H.O.)
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada;
| | - Antoinette Ludwig
- Research Group on Epidemiology of Zoonoses and Public Health (GREZOSP), Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada; (L.T.); (N.H.O.)
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada (PHAC), Saint-Hyacinthe, QC J2S 2M2, Canada
- Correspondence: (A.L.); (D.J.B.); Tel.: +33-673-267-496 (D.J.B.)
| | - Nick H. Ogden
- Research Group on Epidemiology of Zoonoses and Public Health (GREZOSP), Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada; (L.T.); (N.H.O.)
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada (PHAC), Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Robbin L. Lindsay
- Zoonotic Diseases and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada (PHAC), Winnipeg, MB R3E 3R2, Canada; (R.L.L.); (M.I.)
| | - Mahmood Iranpour
- Zoonotic Diseases and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada (PHAC), Winnipeg, MB R3E 3R2, Canada; (R.L.L.); (M.I.)
| | - Carl A. Gagnon
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada;
- Swine and Poultry Infectious Diseases Research Center (CRIPA), Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Dominique J. Bicout
- Biomathématiques et Épidémiologie, EPSP-TIMC, UMR CNRS 5525, Université Grenoble-Alpes, VetAgro Sup, 38700 La Tronche, France
- Laue-Langevin Institute, Theory Group, 71 Avenue des Martyrs, 38042 Grenoble, France
- Correspondence: (A.L.); (D.J.B.); Tel.: +33-673-267-496 (D.J.B.)
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Ogden NH, Fazil A, Arino J, Berthiaume P, Fisman DN, Greer AL, Ludwig A, Ng V, Tuite AR, Turgeon P, Waddell LA, Wu J. Modelling scenarios of the epidemic of COVID-19 in Canada. Can Commun Dis Rep 2020; 46:198-204. [PMID: 32673384 PMCID: PMC7343050 DOI: 10.14745/ccdr.v46i06a08] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Severe acute respiratory syndrome virus 2 (SARS-CoV-2), likely a bat-origin coronavirus, spilled over from wildlife to humans in China in late 2019, manifesting as a respiratory disease. Coronavirus disease 2019 (COVID-19) spread initially within China and then globally, resulting in a pandemic. OBJECTIVE This article describes predictive modelling of COVID-19 in general, and efforts within the Public Health Agency of Canada to model the effects of non-pharmaceutical interventions (NPIs) on transmission of SARS-CoV-2 in the Canadian population to support public health decisions. METHODS The broad objectives of two modelling approaches, 1) an agent-based model and 2) a deterministic compartmental model, are described and a synopsis of studies is illustrated using a model developed in Analytica 5.3 software. RESULTS Without intervention, more than 70% of the Canadian population may become infected. Non-pharmaceutical interventions, applied with an intensity insufficient to cause the epidemic to die out, reduce the attack rate to 50% or less, and the epidemic is longer with a lower peak. If NPIs are lifted early, the epidemic may rebound, resulting in high percentages (more than 70%) of the population affected. If NPIs are applied with intensity high enough to cause the epidemic to die out, the attack rate can be reduced to between 1% and 25% of the population. CONCLUSION Applying NPIs with intensity high enough to cause the epidemic to die out would seem to be the preferred choice. Lifting disruptive NPIs such as shut-downs must be accompanied by enhancements to other NPIs to prevent new introductions and to identify and control any new transmission chains.
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Affiliation(s)
- Nick H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St. Hyacinthe, QC and Guelph, ON
| | - Aamir Fazil
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St. Hyacinthe, QC and Guelph, ON
| | - Julien Arino
- Department of Mathematics & Data Science NEXUS, University of Manitoba, Winnipeg, MB
| | - Philippe Berthiaume
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St. Hyacinthe, QC and Guelph, ON
| | - David N Fisman
- Dalla Lana School of Public Health, University of Toronto, Toronto, ON
| | - Amy L Greer
- Department of Population Medicine, University of Guelph, Guelph, ON
| | - Antoinette Ludwig
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St. Hyacinthe, QC and Guelph, ON
| | - Victoria Ng
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St. Hyacinthe, QC and Guelph, ON
| | - Ashleigh R Tuite
- Dalla Lana School of Public Health, University of Toronto, Toronto, ON
| | - Patricia Turgeon
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St. Hyacinthe, QC and Guelph, ON
| | - Lisa A Waddell
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, St. Hyacinthe, QC and Guelph, ON
| | - Jianhong Wu
- Laboratory for Industrial and Applied Mathematics, Department of Mathematics and Statistics, York University, Toronto, ON
- Fields-CQAM Laboratory of Mathematics for Public Health, York University, Toronto, ON
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Ogden NH, Wilson JRU, Richardson DM, Hui C, Davies SJ, Kumschick S, Le Roux JJ, Measey J, Saul WC, Pulliam JRC. Emerging infectious diseases and biological invasions: a call for a One Health collaboration in science and management. R Soc Open Sci 2019; 6:181577. [PMID: 31032015 PMCID: PMC6458372 DOI: 10.1098/rsos.181577] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 02/18/2019] [Indexed: 05/11/2023]
Abstract
The study and management of emerging infectious diseases (EIDs) and of biological invasions both address the ecology of human-associated biological phenomena in a rapidly changing world. However, the two fields work mostly in parallel rather than in concert. This review explores how the general phenomenon of an organism rapidly increasing in range or abundance is caused, highlights the similarities and differences between research on EIDs and invasions, and discusses shared management insights and approaches. EIDs can arise by: (i) crossing geographical barriers due to human-mediated dispersal, (ii) crossing compatibility barriers due to evolution, and (iii) lifting of environmental barriers due to environmental change. All these processes can be implicated in biological invasions, but only the first defines them. Research on EIDs is embedded within the One Health concept-the notion that human, animal and ecosystem health are interrelated and that holistic approaches encompassing all three components are needed to respond to threats to human well-being. We argue that for sustainable development, biological invasions should be explicitly considered within One Health. Management goals for the fields are the same, and direct collaborations between invasion scientists, disease ecologists and epidemiologists on modelling, risk assessment, monitoring and management would be mutually beneficial.
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Affiliation(s)
- Nick H. Ogden
- National Microbiology Laboratory, Public Health Agency of Canada, Canada
- South African DST-NRF Centre of Excellence in Epidemiological Modelling and Analysis (SACEMA), Stellenbosch University, South Africa
| | - John R. U. Wilson
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
- South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, Cape Town, South Africa
| | - David M. Richardson
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
| | - Cang Hui
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
- Mathematical and Physical Biosciences, African Institute for Mathematical Sciences (AIMS), Muizenberg 7945, South Africa
| | - Sarah J. Davies
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
| | - Sabrina Kumschick
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
- South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont, Cape Town, South Africa
| | - Johannes J. Le Roux
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
- Department of Biological Sciences, Macquarie University, Sydney 2109, Australia
| | - John Measey
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
| | - Wolf-Christian Saul
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
| | - Juliet R. C. Pulliam
- South African DST-NRF Centre of Excellence in Epidemiological Modelling and Analysis (SACEMA), Stellenbosch University, South Africa
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Tyler S, Tyson S, Dibernardo A, Drebot M, Feil EJ, Graham M, Knox NC, Lindsay LR, Margos G, Mechai S, Van Domselaar G, Thorpe HA, Ogden NH. Whole genome sequencing and phylogenetic analysis of strains of the agent of Lyme disease Borrelia burgdorferi from Canadian emergence zones. Sci Rep 2018; 8:10552. [PMID: 30002414 PMCID: PMC6043495 DOI: 10.1038/s41598-018-28908-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 06/27/2018] [Indexed: 12/19/2022] Open
Abstract
Lyme disease is emerging in southern Canada due to range expansion of the tick vector, followed by invasion of the agent of Lyme disease Borrelia burgdorferi sensu stricto. Strain diversity, as determined by Multi Locus Sequence Typing, occurs in this zone of emergence, and this may have its origins in adaptation to ecological niches, and have phenotypic consequences for pathogenicity and serological test performance. Sixty-four unique strains were cultured from ticks collected in southern Canada and the genomes sequenced using the Illumina MiSeq platform. A maximum likelihood phylogenetic tree of the chromosome revealed two large clades with multiple subclades. Consistent with previous studies on this species, the clades were not geographically defined, and some Canadian strains were highly divergent from previously sequenced US strains. There was evidence for recombination in the chromosome but this did not affect the phylogeny. Analysis of chromosomal genes indicated that these are under intense purifying selection. Phylogenies of the accessory genome and chromosome were congruent. Therefore strain differences identified in the phylogeny of chromosomal genes likely act as a proxy for genetic determinants of phenotypic differences amongst strains that are harboured in the accessory genome. Further studies on health implications of strain diversity are needed.
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Affiliation(s)
- Shaun Tyler
- Genomics Core Facility, National Microbiology Laboratory, Public Health Agency of Canada, Canadian Science Centre for Human and Animal Health, 1015, Arlington St., Winnipeg, Manitoba, Canada
| | - Shari Tyson
- Genomics Core Facility, National Microbiology Laboratory, Public Health Agency of Canada, Canadian Science Centre for Human and Animal Health, 1015, Arlington St., Winnipeg, Manitoba, Canada
| | - Antonia Dibernardo
- Zoonotic Diseases and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Michael Drebot
- Zoonotic Diseases and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Edward J Feil
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
| | - Morag Graham
- Genomics Core Facility, National Microbiology Laboratory, Public Health Agency of Canada, Canadian Science Centre for Human and Animal Health, 1015, Arlington St., Winnipeg, Manitoba, Canada
| | - Natalie C Knox
- Genomics Core Facility, National Microbiology Laboratory, Public Health Agency of Canada, Canadian Science Centre for Human and Animal Health, 1015, Arlington St., Winnipeg, Manitoba, Canada
| | - L Robbin Lindsay
- Zoonotic Diseases and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Gabriele Margos
- Ludwig Maximilians Universität München, Department for Infectious Diseases and Zoonoses, Munich, Germany.,National Reference Centre for Borrelia, Oberschleissheim and Bavarian Health and Food Safety Authority, Oberschleissheim, Germany
| | - Samir Mechai
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, J2S 2M2, Canada
| | - Gary Van Domselaar
- Genomics Core Facility, National Microbiology Laboratory, Public Health Agency of Canada, Canadian Science Centre for Human and Animal Health, 1015, Arlington St., Winnipeg, Manitoba, Canada
| | - Harry A Thorpe
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
| | - Nick H Ogden
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Québec, J2S 2M2, Canada.
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Mechai S, Margos G, Feil EJ, Lindsay LR, Michel P, Kotchi SO, Ogden NH. Evidence for an effect of landscape connectivity on Borrelia burgdorferi sensu stricto dispersion in a zone of range expansion. Ticks Tick Borne Dis 2018; 9:1407-1415. [PMID: 30006200 DOI: 10.1016/j.ttbdis.2018.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 06/22/2018] [Accepted: 07/01/2018] [Indexed: 12/29/2022]
Abstract
In North America, different strains of the Lyme disease-causing bacterium Borrelia burgdorferi sensu stricto cluster into phylogenetic groups that are associated with different levels of pathogenicity and, for some, specific rodent reservoir hosts. Here we explore whether landscape connectivity, by impacting host dispersal, influences B. burgdorferi s.s. spread patterns. This question is central to modelling spatial patterns of the spread of Lyme disease risk in the zone of northward range-expansion of B. burgdorferi s.s. in southeastern Canada where the study was conducted. We used multi-locus sequence typing (MLST) to characterise B. burgdorferi s.s. in positive ticks collected at 13 sites in southern Quebec, Canada during the early stages of B. burgdorferi s.s. invasion. We used mixed effects logistic regression to investigate whether landscape connectivity (probability of connectivity; PC) affected the probability that samples collected at different sites were of the same strain (MLST sequence type: ST). PC was calculated from a habitat map based on high spatial resolution (15 m) Landsat 8 imagery to identify woodland habitat that are preferred by rodent hosts of B. burgdorferi s.s. There was a significant positive association between the likelihood that two samples were of the same ST and PC, when PC values were grouped into three categories of low, medium and high. When analysing data for individual STs, samples at different sites were significantly more likely to be the same when PC was higher for the rodent-associated ST1. These findings support the hypothesis that dispersion trajectories of B. burgdorferi s.s. in general, and some rodent-associated strains in particular, are at least partly determined by landscape connectivity. This may suggest that dispersion of B. burgdorferi s.s. is more common by terrestrial mammal hosts (which would likely disperse according to landscape connectivity) than by birds, the dispersal of which is likely less constrained by landscape. This study suggests that accounting for landscape connectivity may improve model-based predictions of spatial spread patterns of B. burgdorferi s.s. The findings are consistent with possible past dispersal patterns of B. burgdorferi s.s. as determined by phylogeographic studies.
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Affiliation(s)
- Samir Mechai
- Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, Saint-Hyacinthe, Québec, J2S 2M2, Canada; Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, Québec, J2S 2M2, Canada.
| | - Gabriele Margos
- Ludwig Maximilians Universität München, Department for Infectious Diseases and Zoonoses, Munich, Germany; National Reference Centre for Borrelia, Oberschleissheim, Germany; Bavarian Health and Food Safety Authority, Oberschleissheim, Germany
| | - Edward J Feil
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
| | - L Robbin Lindsay
- Zoonotic Diseases and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Pascal Michel
- Office of the Chief Science Officer, Public Health Agency of Canada, Ottawa, Ontario, K1A 0K9, Canada
| | - Serge Olivier Kotchi
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, Québec, J2S 2M2, Canada; Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, Saint-Hyacinthe, Québec, J2S 2M2, Canada
| | - Nick H Ogden
- Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, Québec, J2S 2M2, Canada; Public Health Risk Sciences Division, National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, Saint-Hyacinthe, Québec, J2S 2M2, Canada
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8
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Kilpatrick AM, Dobson ADM, Levi T, Salkeld DJ, Swei A, Ginsberg HS, Kjemtrup A, Padgett KA, Jensen PM, Fish D, Ogden NH, Diuk-Wasser MA. Lyme disease ecology in a changing world: consensus, uncertainty and critical gaps for improving control. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0117. [PMID: 28438910 DOI: 10.1098/rstb.2016.0117] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2016] [Indexed: 11/12/2022] Open
Abstract
Lyme disease is the most common tick-borne disease in temperate regions of North America, Europe and Asia, and the number of reported cases has increased in many regions as landscapes have been altered. Although there has been extensive work on the ecology and epidemiology of this disease in both Europe and North America, substantial uncertainty exists about fundamental aspects that determine spatial and temporal variation in both disease risk and human incidence, which hamper effective and efficient prevention and control. Here we describe areas of consensus that can be built on, identify areas of uncertainty and outline research needed to fill these gaps to facilitate predictive models of disease risk and the development of novel disease control strategies. Key areas of uncertainty include: (i) the precise influence of deer abundance on tick abundance, (ii) how tick populations are regulated, (iii) assembly of host communities and tick-feeding patterns across different habitats, (iv) reservoir competence of host species, and (v) pathogenicity for humans of different genotypes of Borrelia burgdorferi Filling these knowledge gaps will improve Lyme disease prevention and control and provide general insights into the drivers and dynamics of this emblematic multi-host-vector-borne zoonotic disease.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.
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Affiliation(s)
- A Marm Kilpatrick
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA
| | | | - Taal Levi
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331, USA
| | - Daniel J Salkeld
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Andrea Swei
- Department of Biology, San Francisco State University, San Francisco, CA 94132, USA
| | - Howard S Ginsberg
- USGS Patuxent Wildlife Research Center, RI Field Station, University of Rhode Island, Kingston, RI 02881, USA
| | - Anne Kjemtrup
- Vector-Borne Disease Section, Division of Communicable Disease Control, California Department of Public Health, Center for Infectious Diseases, Sacramento, CA 95814, USA
| | - Kerry A Padgett
- Vector-Borne Disease Section, Division of Communicable Disease Control, California Department of Public Health, Center for Infectious Diseases, Sacramento, CA 95814, USA
| | - Per M Jensen
- Department of Plant and Environmental Science, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Durland Fish
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, CT, USA
| | - Nick H Ogden
- Public Health Risk Sciences, National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, Saint-Hyacinthe, Quebec, J2S 7C6, Canada
| | - Maria A Diuk-Wasser
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA
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Margos G, Marosevic D, Cutler S, Derdakova M, Diuk-Wasser M, Emler S, Fish D, Gray J, Hunfeld KP, Jaulhac B, Kahl O, Kovalev S, Kraiczy P, Lane RS, Lienhard R, Lindgren PE, Ogden NH, Ornstein K, Rupprecht T, Schwartz I, Sing A, Straubinger RK, Strle F, Voordouw M, Rizzoli A, Stevenson B, Fingerle V. Corrigendum: There is inadequate evidence to support the division of the genus Borrelia. Int J Syst Evol Microbiol 2017; 67:2073. [PMID: 28665266 DOI: 10.1099/ijsem.0.002100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- G Margos
- National Reference Centre for Borrelia, Bavarian Health and Food Safety Authority, Veterinärstr. 2, 85764 Oberschleißheim, Germany
| | - D Marosevic
- European Programme for Public Health Microbiology Training, European Centre of Disease Prevention and Control (ECDC), Stockholm, Sweden.,National Reference Centre for Borrelia, Bavarian Health and Food Safety Authority, Veterinärstr. 2, 85764 Oberschleißheim, Germany
| | - S Cutler
- School of Health Sport and Bioscience, University of East London, Water Lane, London, UK
| | - M Derdakova
- Department of Zoology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - M Diuk-Wasser
- Department of Ecology, Evolution and Environmental Biology, Columbia University, 1200 Amsterdam Avenue, New York, NY 10027, USA
| | - S Emler
- SmartGene Services SARL, Innovation Park, Building C, EPFL-Ecublens, CH-1015 Lausanne, Switzerland
| | - D Fish
- Yale School of Public Health, Laboratory of Epidemiology and Public Health, 60 College Street, New Haven, CT 06510, USA
| | - J Gray
- Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR).,Emeritus Professor of Animal Parasitology, University College Dublin, Dublin, Ireland
| | - K-P Hunfeld
- Zentralinstitut für Labormedizin, Mikrobiologie and Krankenhaushygiene, Krankenhaus Nordwest, Akademisches Lehrkrankenhaus der Johann Wolfgang Goethe-Universität, Steinbacher Hohl 2-26, D-60488 Frankfurt am Main, Frankfurt, Germany.,Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR)
| | - B Jaulhac
- Laboratoire de Bactériologie, CNR des Borrelia, Plateau Technique de Microbiologie, Hôpitaux Universitaires de Strasbourg et Faculté de Médecine de Strasbourg, 1 rue Koeberlé, Strasbourg 67000, France.,Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR)
| | - O Kahl
- tick-radar GmbH, Haderslebener Str. 9, Berlin 12163, Germany.,Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR)
| | - S Kovalev
- Molecular Genetics Lab (www.dnk-ural.ru) Biology Department, Ural Federal University named after the first President of Russia B.N.Yeltsin, Lenin Avenue, Yekaterinburg 620000, Russia
| | - P Kraiczy
- Institute of Medical Microbiology and Infection Control, University Hospital Frankfurt, Paul-Ehrlich-Str, Frankfurt/Main 40, 60596, Germany
| | - R S Lane
- Environmental Science, Policy and Management, University of California Berkeley, 130 Mulford Hall, Berkeley CA 94720, California, USA
| | - R Lienhard
- Borrelia Laboratory for the National Reference Centre of Tick Diseases (CNRT/ NRZK), ADMed Microbiology, La Chaux-de-Fonds 2303, Switzerland
| | - P E Lindgren
- Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden.,Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR)
| | - N H Ogden
- Director, Public Health Risk Sciences Division, National Microbiology Laboratory, @ Saint-Hyacinthe and Guelph, Public Health Agency of Canada, Saint-Hyacinthe, Canada
| | - K Ornstein
- Clinical and Experimental Infectious Medicine Section, Department of Clinical Sciences, Lund University, Sweden.,Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR)
| | - T Rupprecht
- Klinikum Dachau, Abt. Neurology u. Schlafmedizinisches Zentrum, Krankenhausstr. 15, 8521 Dachau, Germany.,Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR)
| | - I Schwartz
- Department of Microbiology and Immunology, School of Medicine, New York Medical College, Basic Sciences Building, Valhalla, NY 10595, USA
| | - A Sing
- National Reference Centre for Borrelia, Bavarian Health and Food Safety Authority, Veterinärstr. 2, 85764 Oberschleißheim, Germany
| | - R K Straubinger
- Chair Bacteriology and Mykology, Department of Veterinary Science, Veterinary Faculty, LMU Munich, Veterinärstraße, München 13, 80539, Gemany
| | - F Strle
- Department of Infectious Diseases, University Medical Centre Ljubljana, Ljubljana, Slovenia.,Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR)
| | - M Voordouw
- Université de Neuchâtel, Institut de Biologie, Laboratoire d'Ecologie et Evolution des Parasites, Rue Emile-Argand 11, CH-2000, Neuchâtel, Switzerland
| | - A Rizzoli
- Fondazione Edmund Mach, Research and Innovation Centre, Via Mach, 1, San Michele all'Adige, Trento, Italy
| | - B Stevenson
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, MS421 Chandler Medical Center, Lexington, Kentucky, 40536-0298, USA
| | - V Fingerle
- Members of the Steering Committee of the ESCMID Study Group for Borrelia (ESGBOR).,National Reference Centre for Borrelia, Bavarian Health and Food Safety Authority, Veterinärstr. 2, 85764 Oberschleißheim, Germany
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Ogden NH, Lindsay LR. Effects of Climate and Climate Change on Vectors and Vector-Borne Diseases: Ticks Are Different. Trends Parasitol 2016; 32:646-656. [PMID: 27260548 DOI: 10.1016/j.pt.2016.04.015] [Citation(s) in RCA: 154] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 04/19/2016] [Accepted: 04/21/2016] [Indexed: 01/05/2023]
Abstract
There has been considerable debate as to whether global risk from vector-borne diseases will be impacted by climate change. This has focussed on important mosquito-borne diseases that are transmitted by the vectors from infected to uninfected humans. However, this debate has mostly ignored the biological diversity of vectors and vector-borne diseases. Here, we review how climate and climate change may impact those most divergent of arthropod disease vector groups: multivoltine insects and hard-bodied (ixodid) ticks. We contrast features of the life cycles and behaviour of these arthropods, and how weather, climate, and climate change may have very different impacts on the spatiotemporal occurrence and abundance of vectors, and the pathogens they transmit.
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Affiliation(s)
- Nick H Ogden
- National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, Saint-Hyacinthe, Québec, J2S 7C6, Canada; Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada; National Microbiology Laboratory, Public Health Agency of Canada, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba, R3E 3R2, Canada.
| | - L Robbin Lindsay
- National Microbiology Laboratory, Public Health Agency of Canada, National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba, R3E 3R2, Canada
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11
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Ogden NH, Barker IK, Francis CM, Heagy A, Lindsay LR, Hobson KA. Response to letter regarding article "How far north are migrant birds transporting the tick Ixodes scapularis in Canada? Insights from stable hydrogen isotope analyses of feathers". Ticks Tick Borne Dis 2016; 7:329-30. [PMID: 26776880 DOI: 10.1016/j.ttbdis.2015.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 12/02/2015] [Indexed: 11/19/2022]
Abstract
In this letter we respond to correspondence and clarify the intent and importance of our article.
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Affiliation(s)
- N H Ogden
- National Microbiology Laboratory, Public Health Agency of Canada, Canada; Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), 3200 Sicotte, Saint-Hyacinthe, Quebec, Canada J2S 7C6.
| | - I K Barker
- Canadian Wildlife Health Cooperative, Dept. of Pathobiology, Ontario Veterinary College, University of Guelph, 50 Stone Road, Guelph, ON, Canada N1G 2W1.
| | - C M Francis
- Canadian Wildlife Service, Environment Canada, 1125 Colonel By, Ottawa, ON, Canada K1A 0H3.
| | - A Heagy
- Bird Studies Canada, 115 Front St., Port Rowan, ON, Canada N0E 1M0.
| | - L R Lindsay
- Zoonotic Diseases & Special Pathogens Division, Public Health Agency of Canada, National Microbiology Laboratory, 1015 Arlington Street, Winnipeg, Canada R3E 3R2.
| | - K A Hobson
- Environment Canada, 11 Innovation Blvd, Saskatoon, Saskatchewan, Canada S7N 3H5.
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12
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Abstract
Current approaches for prevention of tick bites, Lyme disease, and other tick-borne diseases are described. Particular attention is paid to 4 risk-reduction strategies: (i) avoiding risk areas; (ii) personal protective measures that reduce the risk of tick bites or transmission of the agent of Lyme disease, Borrelia burgdorferi; (iii) reducing the number of infected ticks in the environment; and (iv) use of prophylactic antibiotic treatments following a bite to prevent clinical Lyme disease.
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Affiliation(s)
- Nick H Ogden
- National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, Saint-Hyacinthe, Quebec J2S 7C6, Canada.
| | - L Robbin Lindsay
- National Microbiology Laboratory, Public Health Agency of Canada, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada
| | - Steven W Schofield
- Communicable Disease Control Program, Force Health Protection, Department of National Defence, 1745 Alta Vista Drive, Ottawa, Ontario K1A 0K6, Canada
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13
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Barton-Forbes M, Leonard E, Lindsay LR, Langley JM, Koffi JK, Ogden NH. Tick bites in the Lyme light. Paediatr Child Health 2015; 20:237-8. [PMID: 26175558 DOI: 10.1093/pch/20.5.237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2015] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - E Leonard
- Centre for Food Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Ottawa, Ontario
| | - L R Lindsay
- National Microbiology Laboratory, National Public Health Laboratories, Public Health Agency of Canada, Winnipeg, Manitoba
| | - J M Langley
- Departments of Paediatrics and Community Health and Epidemiology, Dalhousie University and IWK Health Centre, Halifax, Nova Scotia
| | - J K Koffi
- Centre for Food Environmental and Zoonotic Infectious Diseases
| | - N H Ogden
- Laboratory for Foodborne Zoonoses, National Public Health Laboratories, Public Health Agency of Canada, Saint-Hyacinthe, Quebec
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14
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Ogden NH, Barker IK, Francis CM, Heagy A, Lindsay LR, Hobson KA. How far north are migrant birds transporting the tick Ixodes scapularis in Canada? Insights from stable hydrogen isotope analyses of feathers. Ticks Tick Borne Dis 2015; 6:715-20. [PMID: 26100493 DOI: 10.1016/j.ttbdis.2015.06.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 05/15/2015] [Accepted: 06/09/2015] [Indexed: 10/23/2022]
Abstract
Lyme disease is emerging in Canada because of northward range expansion of the tick vector Ixodes scapularis. It is hypothesised that I. scapularis feeding on passerine birds migrating north in spring are important in founding new I. scapularis populations leading to northward range expansion. However, there are no studies on how far north I. scapularis may be carried, only inferences from passive tick surveillance. We used stable hydrogen isotope (δ(2)H) analysis of rectrices collected from northward migrating, I. scapularis-carrying, passerine birds captured in Canada to estimate how far north I. scapularis may be carried. Rectrices are usually grown close to breeding sites and their δ(2)H values reflect those in the environment, which vary strongly with latitude in North America. Passerines usually return to their breeding or natal sites so δ(2)H values of rectrices of northward migrating birds can identify the likely latitudinal bands of their intended destinations. In 2006 we analysed δ(2)H from rectrices of 73 I. scapularis-carrying birds captured at five migration monitoring stations, mainly from southern Ontario. Values of δ(2)H ranged from -33 to -124‰, suggesting 19/71 (26.7%) birds were destined for latitude band B (the most southerly part of Ontario), 40/71 (56.3%) birds were destined for band C (which extends from southern Ontario, Quebec and the Maritimes to southern James Bay) and 12/71 (16.9%) birds were destined for bands D and E (which extend from northern Ontario and Quebec into the southern Canadian Arctic). This indicates that many I. scapularis-carrying migratory birds in spring have destinations far north in Canada, including some farther north than the current region of climatic suitability for I. scapularis. These findings support the hypothesis that I. scapularis may continue to be spread north by spring migrating passerines. Some thrush species may be particularly implicated in far northward dispersion of I. scapularis.
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Affiliation(s)
- N H Ogden
- National Microbiology Laboratory, Public Health Agency of Canada, Saint Hyacinth, QC, Canada; Groupe de Recherche en Épidémiologie des Zoonoses et Santé Publique (GREZOSP), 3200 Sicotte, Saint-Hyacinthe, QC, Canada J2S 7C6.
| | - I K Barker
- Canadian Wildlife Health Cooperative, Department of Pathobiology, Ontario Veterinary College, University of Guelph, 50 Stone Road, Guelph, ON, Canada N1G 2W1.
| | - C M Francis
- Canadian Wildlife Service, Environment Canada, 1125 Colonel By, Ottawa, ON, Canada K1A 0H3.
| | - A Heagy
- Bird Studies Canada, 115 Front St., Port Rowan, ON, Canada N0E 1M0.
| | - L R Lindsay
- Zoonotic Diseases & Special Pathogens Division, Public Health Agency of Canada, National Microbiology Laboratory, 1015 Arlington Street, Winnipeg, MB, Canada R3E 3R2.
| | - K A Hobson
- Environment Canada, 11 Innovation Blvd, Saskatoon, SK, Canada S7N 3H5.
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15
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Ogden NH, Koffi JK, Lindsay LR, Fleming S, Mombourquette DC, Sanford C, Badcock J, Gad RR, Jain-Sheehan N, Moore S, Russell C, Hobbs L, Baydack R, Graham-Derham S, Lachance L, Simmonds K, Scott AN. Surveillance for Lyme disease in Canada, 2009 to 2012. Can Commun Dis Rep 2015; 41:132-145. [PMID: 29769945 PMCID: PMC5933887 DOI: 10.14745/ccdr.v41i06a03] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVES To summarize the first four years of national surveillance for Lyme disease in Canada from 2009 to 2012 and to conduct a preliminary comparison of presenting clinical manifestations in Canada and the United States. METHODS The numbers and incidence of reported cases by province, month, year, age and sex were calculated. Logistic regression was used to examine trends over time. Acquisition locations were mapped and presenting clinical manifestations reported for jurisdictions where data was available. Variations by province, year, age and sex as well as presenting clinical symptoms were explored by logistic regression. An initial comparative analysis was made of presenting symptoms in Canada and the United States. RESULTS The numbers of reported cases rose significantly from 144 in 2009 to 338 in 2012 (coefficient = 0.34, standard error = 0.07, P <0.05), mostly due to an increased incidence of infections acquired in Canada. More cases were classified as 'confirmed' (71.5%) than 'probable' (28.5%). Most cases occurred in locations where vector tick populations were known to be present. More men than women were affected (53.4% versus 46.6%), incidence was highest in adults aged 55 to 74 years and in children aged five to 14 years. Most cases (95%) were acquired from April to November. Of cases acquired in endemic areas, 39.7% presented with manifestations of early Lyme disease, while 60.3% had manifestations of disseminated Lyme disease. There were significant differences among age groups, sexes and provinces in the frequencies of reported clinical manifestations. The proportion of cases acquired in endemic areas presenting with early Lyme disease was lower than that reported in the US. CONCLUSION Lyme disease incidence is increasing in Canada. Most cases are acquired where vector tick populations are spreading and this varies geographically within and among provinces. There is also variation in the frequency of age, season and presenting manifestations. The lower proportion of cases presenting with early Lyme disease in Canada compared with the US suggests lower awareness of early Lyme disease in Canada, but this requires further study.
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Affiliation(s)
- NH Ogden
- Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Ottawa, ON
| | - JK Koffi
- Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Ottawa, ON
| | - LR Lindsay
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB
| | - S Fleming
- Public Health Branch, Nova Scotia Department of Health and Wellness, Halifax, NS
| | - DC Mombourquette
- Public Health Branch, Nova Scotia Department of Health and Wellness, Halifax, NS
| | - C Sanford
- Population Health Assessment and Surveillance, Prince Edward Island Department of Health and Wellness, Charlottetown, PE
| | - J Badcock
- Office of the Chief Medical Officer of Health, New Brunswick Department of Health, NB
| | - RR Gad
- Office of the Chief Medical Officer of Health, New Brunswick Department of Health, NB
| | - N Jain-Sheehan
- Enteric, Zoonotic and Vector-Borne Diseases, Public Health Ontario, Toronto, ON
| | - S Moore
- Enteric, Zoonotic and Vector-Borne Diseases, Public Health Ontario, Toronto, ON
| | - C Russell
- Enteric, Zoonotic and Vector-Borne Diseases, Public Health Ontario, Toronto, ON
| | - L Hobbs
- Enteric, Zoonotic and Vector-Borne Diseases, Public Health Ontario, Toronto, ON
| | - R Baydack
- Communicable Disease Control Branch, Manitoba Health Healthy Living and Seniors, Winnipeg, MB
| | - S Graham-Derham
- Communicable Disease Control Branch, Manitoba Health Healthy Living and Seniors, Winnipeg, MB
| | - L Lachance
- Surveillance and Assessment Branch, Alberta Health, Calgary, AB
| | - K Simmonds
- Surveillance and Assessment Branch, Alberta Health, Calgary, AB
| | - AN Scott
- Surveillance and Assessment Branch, Alberta Health, Calgary, AB
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Abstract
Since the spring of 2014, there has been a large increase in travel-related chikungunya cases diagnosed in Canada. As of December 9, 2014, 320 confirmed and 159 probable cases have been diagnosed in Canada, with the majority of provinces identifying at least one imported case. This surge in Canadian infections has been associated with the incursion of chikungunya virus into the Caribbean and the expansion of the virus in the Americas. Ongoing outbreaks in the Asia-Pacific region have also contributed to imported cases among Canadian travellers. Heightened awareness of chikungunya among clinicians is key to diagnosis. This highlights the need to ask for a travel history from anyone who presents with fever or recent onset of polyarthralgia, and to consider testing by provincial laboratories and the National Microbiology Laboratory for chikungunya virus and other diseases as indicated. Also essential is continued communication with travellers regarding the use of preventative measures to decrease the risk of exposure to mosquitoes when travelling to endemic areas.
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Affiliation(s)
- MA Drebot
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB
- Corresponding author:
| | - K Holloway
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB
| | - H Zheng
- Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Ottawa, ON
| | - NH Ogden
- Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Ottawa, ON
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Ogden NH, Koffi JK, Pelcat Y, Lindsay LR. Environmental risk from Lyme disease in central and eastern Canada: a summary of recent surveillance information. Can Commun Dis Rep 2014; 40:74-82. [PMID: 29769885 PMCID: PMC5864485 DOI: 10.14745/ccdr.v40i05a01] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
BACKGROUND Lyme disease is the most commonly reported vector-borne disease in the temperate world. It is emerging in central and eastern Canada due to spread of the tick vector Ixodes scapularis into and within Canada to form new areas of environmental risk known as Lyme disease-endemic areas. Identifying the geographic location of Lyme disease-endemic areas is important to identify the population at risk, target interventions, and inform the clinical diagnosis of Lyme disease patients. OBJECTIVE To provide an up-to-date picture of current and emerging areas of Lyme disease risk in eastern and central Canada by summarizing recent information on Lyme disease-endemic areas, and surveillance for I. scapularis ticks. METHODS Data on locations where I. scapularis have been found in field surveillance studies by a range of federal and provincial organizations were collated and mapped to obtain a fuller picture of the occurrence of I. scapularis in Canada. The geographic locations of ticks submitted in passive tick surveillance were mapped for comparison. RESULTS The number of confirmed Lyme disease-endemic areas in southern Manitoba, southern and eastern Ontario, southern Quebec, southern New Brunswick and in some locations in Nova Scotia increased from 10 in 2009 to 22 confirmed endemic areas in 2012. The collated field surveillance data indicated that I. scapularis tick populations and Lyme disease risk are more geographically widespread than known Lyme disease-endemic areas and that the pattern of emergence of tick populations varies among provinces. There was a tenfold increase in the numbers of I. scapularis reported for passive surveillance from 2 059 submissions from 1990 to 2003 to 25 738 submissions from 2004 to 2012. CONCLUSIONS The increasing numbers of Lyme disease-endemic areas, the much wider distribution of tick populations identified by field surveillance, as well as the marked increase in numbers of ticks identified through passive surveillance suggest that the geographic scope of environmental risk of acquiring Lyme disease is expanding in central and eastern Canada, although here it still remains mostly limited to the southern parts of five provinces.
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Affiliation(s)
- NH Ogden
- Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, Quebec
- Corresponding author:
| | - JK Koffi
- Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, Quebec
| | - Y Pelcat
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba
| | - LR Lindsay
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba
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Ogden NH, Mechai S, Margos G. Changing geographic ranges of ticks and tick-borne pathogens: drivers, mechanisms and consequences for pathogen diversity. Front Cell Infect Microbiol 2013; 3:46. [PMID: 24010124 PMCID: PMC3756306 DOI: 10.3389/fcimb.2013.00046] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/04/2013] [Indexed: 12/30/2022] Open
Abstract
The geographic ranges of ticks and tick-borne pathogens are changing due to global and local environmental (including climatic) changes. In this review we explore current knowledge of the drivers for changes in the ranges of ticks and tick-borne pathogen species and strains via effects on their basic reproduction number (R0), and the mechanisms of dispersal that allow ticks and tick-borne pathogens to invade suitable environments. Using the expanding geographic distribution of the vectors and agent of Lyme disease as an example we then investigate what could be expected of the diversity of tick-borne pathogens during the process of range expansion, and compare this with what is currently being observed. Lastly we explore how historic population and range expansions and contractions could be reflected in the phylogeography of ticks and tick-borne pathogens seen in recent years, and conclude that combined study of currently changing tick and tick-borne pathogen ranges and diversity, with phylogeographic analysis, may help us better predict future patterns of invasion and diversity.
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Affiliation(s)
- Nick H Ogden
- Zoonoses Division, Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, QC, Canada. nicholas.ogden@ phac-aspc.gc.ca
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19
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Bouchard C, Beauchamp G, Leighton PA, Lindsay R, Bélanger D, Ogden NH. Does high biodiversity reduce the risk of Lyme disease invasion? Parasit Vectors 2013; 6:195. [PMID: 23816142 PMCID: PMC3728044 DOI: 10.1186/1756-3305-6-195] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 06/22/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND It has been suggested that increasing biodiversity, specifically host diversity, reduces pathogen and parasite transmission amongst wildlife (causing a "dilution effect"), whereby transmission amongst efficient reservoir hosts, (e.g. Peromyscus spp. mice for the agent of Lyme disease Borrelia burgdorferi) is reduced by the presence of other less efficient host species. If so, then increasing biodiversity should inhibit pathogen and parasite invasion. METHODS We investigated this hypothesis by studying invasion of B. burgdorferi and its tick vector Ixodes scapularis in 71 field sites in southeastern Canada. Indices of trapped rodent host diversity, and of biodiversity of the wider community, were investigated as variables explaining the numbers of I. scapularis collected and B. burgdorferi infection in these ticks. A wide range of alternative environmental explanatory variables were also considered. RESULTS The observation of low I. scapularis abundance and low B. burgdorferi infection prevalence in sites where I. scapularis were detected was consistent with early-stage invasion of the vector. There were significant associations between the abundance of ticks and season, year of study and ambient temperature. Abundance of host-seeking larvae was significantly associated with deer density, and abundance of host-seeking larvae and nymphs were positively associated with litter layer depth. Larval host infestations were lower where the relative proportion of non-Peromyscus spp. was high. Infestations of hosts with nymphs were lower when host species richness was higher, but overall nymphal abundance increased with species richness because Peromyscus spp. mouse abundance and host species richness were positively correlated. Nymphal infestations of hosts were lower where tree species richness was higher. B. burgdorferi infection prevalence in ticks varied significantly with an index of rates of migratory bird-borne vector and pathogen invasion. CONCLUSIONS I. scapularis abundance and B. burgdorferi prevalence varied with explanatory variables in patterns consistent with the known biology of these species in general, and in the study region in particular. The evidence for a negative effect of host biodiversity on I. scapularis invasion was mixed. However, some evidence suggests that community biodiversity beyond just host diversity may have direct or indirect inhibitory effects on parasite invasion that warrant further study.
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Affiliation(s)
- Catherine Bouchard
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
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20
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Mechai S, Feil EJ, Gariepy TD, Gregory TR, Lindsay LR, Millien V, Ogden NH. Investigation of the population structure of the tick vector of Lyme disease Ixodes scapularis (Acari: Ixodidae) in Canada using mitochondrial cytochrome C oxidase subunit I gene sequences. J Med Entomol 2013; 50:560-570. [PMID: 23802450 DOI: 10.1603/me12178] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Genotyping of Ixodes scapularis Say (Acari: Ixodidae) ticks could enhance understanding of the occurrence and genotypes of I. scapularis-borne pathogens. We investigated the utility of mitochondrial (mt) Cytochrome C Oxidase subunit I gene (cox1) sequences as a tool for understanding the population structure of I. scapularis collected in Canada, where we also investigated the geographic occurrence of different cox1 haplotypes. Sequences obtained from 414 ticks were one of 55 unique haplotypes, most of which grouped into one of six clades. Demographic analysis suggested that cox1 sequences have haplotype and nucleotide diversity comparable to other mt genes. All haplotypes were connected in a single minimum spanning network tree. Despite low fixation index values there were significant differences in the frequency of occurrence of haplotypes of different clades among four geographic regions: 1) Alberta to western Ontario, 2) eastern Ontario, 3) Quebec, and 4) Atlantic Provinces; suggesting that cox1 sequences could reveal population structure differences between I. scapularis in geographically separated populations of northeastern and midwestern North America. Spatial clusters of ticks of the same haplotype identified in regions of southern Quebec and southern Ontario where I. scapularis is invading were consistent with population bottlenecks associated with founder events. These findings suggest that cox1 sequences are useful for the study of I. scapularis population structure, are of sufficient diversity that spatial analyses of haplotypes can be used to identify where I. scapularis is emerging in southern Canada, and may be useful for exploring differences between northeastern and midwestern populations of I. scapularis.
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Affiliation(s)
- S Mechai
- Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
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Bouchard C, Leighton PA, Beauchamp G, Nguon S, Trudel L, Milord F, Lindsay LR, Bélanger D, Ogden NH. Harvested white-tailed deer as sentinel hosts for early establishing Ixodes scapularis populations and risk from vector-borne zoonoses in southeastern Canada. J Med Entomol 2013; 50:384-393. [PMID: 23540128 DOI: 10.1603/me12093] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Due to recent establishment of the blacklegged tick, Ixodes scapularis Say, in southeastern Canada, tick-borne zoonoses (Lyme disease, human granulocytotropic anaplasmosis, and babesiosis) are of growing concern for public health. Using white-tailed deer (Odocoileus virginianus) culled in southwestern Quebec during 2007-2008, we investigated whether hunter-killed deer could act as sentinels for early establishing tick populations and for tick-borne pathogens. Accounting for environmental characteristics of culling sites, and age and sex of deer, we investigated whether their tick infestation levels could identify locations of known tick populations detected in active surveillance, presumed tick populations detected by passive surveillance, or both. We also used spatial cluster analyses to identify spatial patterns of tick infestation and occurrence of tick-borne zoonoses infection in ticks collected from the deer. Adult ticks were found on 15% of the 583 deer examined. Adult male deer had the greatest number (approximately 90%) of adult ticks. Overall, 3, 15, and 0% of the ticks collected were polymerase chain reaction (PCR)-positive for Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti, respectively. Our statistical analyses suggest that sex and age of deer, temperature, precipitation, and an index of tick dispersion by migratory birds were significantly associated with tick infestation levels. Cluster analysis identified significant clusters of deer carrying ticks PCR-positive for A. phagocytophilum, and for deer carrying two or more I. scapularis. Our study suggests that hunter-killed deer may be effective as sentinels for emerging areas of tick-borne anaplasmosis. They may have limited use as sentinels for early emerging I. scapularis tick populations and emerging Lyme disease risk.
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Affiliation(s)
- C Bouchard
- Groupe de recherche en epidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, C.P. 5000, Saint-Hyacinthe, J2S 7C6 QC, Canada.
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Bouchard C, Beauchamp G, Nguon S, Trudel L, Milord F, Lindsay LR, Bélanger D, Ogden NH. Associations between Ixodes scapularis ticks and small mammal hosts in a newly endemic zone in southeastern Canada: implications for Borrelia burgdorferi transmission. Ticks Tick Borne Dis 2011; 2:183-90. [PMID: 22108010 DOI: 10.1016/j.ttbdis.2011.03.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 10/15/2022]
Abstract
Immature Ixodes scapularis infestation and Borrelia burgdorferi infection of wild small mammals were studied from June to October in 2007 and from May to October in 2008 at 71 study sites in a zone where I. scapularis populations and environmental Lyme disease risk are emerging in southwestern Quebec. Seasonal host-seeking activity of immature I. scapularis was similar to patterns reported previously in Canada and the USA: nymphal activity peaked in spring while larval activity peaked in late summer. Synchronous activity of nymphs with some larvae was observed in late spring, which could favour establishment of B. burgdorferi strains that cause short-lived infections in their hosts. White-footed mice (Peromyscus leucopus), deer mice (P. maniculatus), chipmunks (Tamias striatus), and red squirrels (Tamiasciurus hudsonicus) carried 92.0% of the larvae and 94.2% of the nymphs collected. Adult male white-footed mice carried significantly larger numbers of both larval and nymphal I. scapularis than other species and classes of small mammals (different demographic groups or physiological status: age, sex, sexual activity). We conclude that seasonality and host association were comparable to previous studies in North America, even in the context of a newly endemic pattern of low infection prevalence and low densities of host-seeking and feeding I. scapularis in southwestern Quebec. Our studies suggest that B. burgdorferi transmission cycles are focused on adult male mice (which carried 35% of all feeding ticks collected in the study), so control methods targeting this class of hosts may be particularly effective. However, our study also suggested that habitats containing a diverse host structure may dilute transmission cycles by partitioning of nymphal and larval ticks on different host species.
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Affiliation(s)
- C Bouchard
- Groupe de recherche en épidémiologie des zoonoses et santé publique, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada.
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Wang J, Ogden NH, Zhu H. The impact of weather conditions on Culex pipiens and Culex restuans (Diptera: Culicidae) abundance: a case study in Peel Region. J Med Entomol 2011; 48:468-75. [PMID: 21485391 DOI: 10.1603/me10117] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Mosquito populations are sensitive to long-term variations in climate and short-term variations in weather. Mosquito abundance is a key determinant of outbreaks of mosquito-borne diseases, such as West Nile virus (WNV). In this work, the short-term impact of weather conditions (temperature and precipitation) on Culex pipiens L.-Culex restuans Theobald mosquito abundance in Peel Region, Ontario, Canada, was investigated using the 2002-2009 mosquito data collected from the WNV surveillance program managed by Ontario Ministry of Health and Long-Term Care and a gamma-generalized linear model. There was a clear association between weather conditions (temperature and precipitation) and mosquito abundance, which allowed the definition of threshold criteria for temperature and precipitation conditions for mosquito population growth. A predictive statistical model for mosquito population based on weather conditions was calibrated using real weather and mosquito surveillance data, and validated using a subset of surveillance data. Results showed that WNV vector abundance on any one day could be predicted with reasonable accuracy from relationships with mean degree-days >9 degrees C over the 11 preceding days, and precipitation 35 d previously. This finding provides optimism for the development of weather-generated forecasting for WNV risk that could be used in decision support systems for interventions such as mosquito control.
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Affiliation(s)
- Jiafeng Wang
- Laboratory of Mathematical Parallel Systems/Centre for Disease Modelling (LAMPS/CDM), Department of Mathematics and Statistics, York University, Toronto, Ontario M3J 1P3 Canada
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Karimuribo ED, Fitzpatrick JL, Swai ES, Bell C, Bryant MJ, Ogden NH, Kambarage DM, French NP. Prevalence of subclinical mastitis and associated risk factors in smallholder dairy cows in Tanzania. Vet Rec 2008; 163:16-21. [PMID: 18603630 DOI: 10.1136/vr.163.1.16] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
A cross-sectional study was carried out on 200 randomly selected farms in each of the Iringa and Tanga regions of Tanzania to estimate the prevalence and risk factors for subclinical mastitis in dairy cows kept by smallholders. Subclinical mastitis was assessed using the California mastitis test (cmt), and by the bacteriological culture of 1500 milk samples collected from 434 clinically normal cows. The percentages of the cows (and quarters) with subclinical mastitis were 75.9 per cent (46.2 per cent) when assessed by the cmt and 43.8 per cent (24.3 per cent) when assessed by culture. Factors significantly associated with an increased risk of a cmt-positive quarter were Boran breed (odds radio [or]=3.51), a brought-in cow (rather than homebred) (or=2.39), peak milk yield, and age. The stripping method of hand milking was associated with a significantly lower prevalence of cmt-positive quarters (or=0.51). The cmt-positive cows were more likely to be culture positive (or=4.51), as were brought-in (or=2.10) and older cows.
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Affiliation(s)
- E D Karimuribo
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
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Ogden NH, Artsob H, Lindsay LR, Sockett PN. Lyme disease: a zoonotic disease of increasing importance to Canadians. Can Fam Physician 2008; 54:1381-1384. [PMID: 18854461 PMCID: PMC2567255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- N H Ogden
- Centre for Foodborne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada.
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Ogden NH, Lindsay LR, Morshed M, Sockett PN, Artsob H. The rising challenge of Lyme borreliosis in Canada. Can Commun Dis Rep 2008; 34:1-19. [PMID: 18290267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- N H Ogden
- Foodborne, Waterborne and Zoonotic Infections Division, Public Health Agency of Canada, St-Hyacinthe, Quebec, Canada
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Swai ES, French NP, Karimuribo ED, Fitzpatrick JL, Bryant MJ, Kambarage DM, Ogden NH. Prevalence and determinants of Cryptosporidium spp. infection in smallholder dairy cattle in Iringa and Tanga Regions of Tanzania. ACTA ACUST UNITED AC 2007; 74:23-9. [PMID: 17708150 DOI: 10.4102/ojvr.v74i1.136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
The prevalence of Cryptosporidium spp. infection in a cross-sectional study of dairy cattle, from two contrasting dairying regions in Tanzania, were determined by staining smears of faecal samples with the modified Ziehl-Neelsen technique. Of the 1 126 faecal samples screened, 19.7% were positive for Cryptosporidium spp. The prevalence was lower in Tanga Region than in Iringa Region. The prevalence of affected farms was 20% in Tanga and 21% in Iringa. In both regions, the probability of detecting Cryptosporidium oocysts in faeces varied with animal class, but these were not consistent in both regions. In Tanga Region, Cryptosporidium oocysts were significantly more likely to be found in the faeces of milking cows. In Iringa Region, the likelihood that cattle had Cryptosporidium-positive faeces declined with age, and milking cattle were significantly less likely to have Cryptosporidium-positive faeces. In this region, 7% of cattle were housed within the family house at night, and this was marginally associated with a higher likelihood that animals had Cryptosporidium-positive faeces. Our study suggests that even though herd sizes are small, Cryptosporidium spp. are endemic on many Tanzanian smallholder dairy farms. These protozoa may impact on animal health and production, but also on human health, given the close associations between the cattle and their keepers. Further studies are required to assess these risks in more detail, and understand the epidemiology of Cryptosporidium spp. in this management system.
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Affiliation(s)
- E S Swai
- Veterinary Investigation Centre, Box 1068, Arusha, Tanzania.
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Swai ES, Karimuribo ED, French NP, Fitzpatrick JL, Bryant MJ, Kambarage DM, Ogden NH. Seroprevalence of Babesia bigeminain smallholder dairy cattle in Tanzania and associated risk factors. J S Afr Vet Assoc 2007; 78:15-20. [PMID: 17665760 DOI: 10.4102/jsava.v78i1.280] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Variations in the seroprevalence of antibody to Babesia bigemina infection by farm and animal level risk factors were investigated for 2 contrasting regions of Tanga and Iringa in Tanzania. Tanga is situated in the eastern part of the country and has typical tropical coast climate while Iringa is situated in the Southern Highlands and has a tropical highland climate. Two hundred farms from each region were selected using simple random sampling procedure and visited once between January 1999 and April 1999. Blood samples were collected from 1329 smallholder dairy animals on selected farms for harvesting serum which was subsequently used for serodiagnosis of B. bigemina using an indirect enzyme linked immuno-sorbent assay (ELISA). Of the 1329 sera samples screened, 34.9 % were positive for B. bigemina. The prevalence was higher in Iringa Region [43 %, 95% confidence intervals (CI) = 39.5-47.3] than in Tanga Region (27 %, CI = 23.6-30.5). Using a logistic binomial regression model as an analytical method for predicting the likelihood of animal seropositivity, we found (in both regions) that the risk of positive reaction varied with the animal's age, history of grazing and geographical location. Seroprevalence increased with age (b=0.01 and 0.01 per year of age, P0.005 in Tanga and Iringa, respectively). Animals located in Lushoto and Iringa urban district were associated with increased risk of seropositivity [Odds ratio (OR)=4.24, P=0.001, for Lushoto, and OR=1.81, P=0.040, for Iringa Urban, respectively). Animals grazed 3 months prior to sampling had higher odds for seropositivity than zero/semi-grazed, despite farmer-reported high frequency of tick control (OR = 2.71, P = 0.0087, for Tanga, and OR = 4.53, P = 0.001, for Iringa). Our study suggests that even though herd sizes are small, B. bigemina infection is widespread in many smallholder dairy farms and endemic stability with respect to this disease has not yet been attained, but the observed levels are sufficiently high to ensure that clinical disease would be a risk.
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Affiliation(s)
- E S Swai
- Tanga Dairy development Programme (TDDP), PO Box 1474, Tanga, Tanzania.
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Bown KJ, Begon M, Bennett M, Birtles RJ, Burthe S, Lambin X, Telfer S, Woldehiwet Z, Ogden NH. SympatricIxodes triangulicepsandIxodes ricinusTicks Feeding on Field Voles (Microtus agrestis): Potential for Increased Risk ofAnaplasma phagocytophilumin the United Kingdom? Vector Borne Zoonotic Dis 2006; 6:404-10. [PMID: 17187576 DOI: 10.1089/vbz.2006.6.404] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The importance of wild rodents as reservoirs of zoonotic tick-borne pathogens is considered low in the United Kingdom because, in studies to date, those parasitized by exophilic Ixodes ricinus ticks carry almost exclusively larvae and thus have a minor role in transmission cycles. In a cross-sectional study, 11 (6.7%) of 163 field voles (Microtus agrestis) captured at field sites in Northern England were PCR-positive for Anaplasma phagocytophilum. The voles were found to act as hosts for both larval and nymphal I. ricinus and all stages of the nidicolous tick I. trianguliceps, and eight individuals were infested with ticks of both species at the same time. Two of 158 larval and one of 13 nymphal I. ricinus, as well as one of 14 larval and one of 15 nymphal I. trianguliceps collected from the rodents were PCR-positive. These findings suggest that habitats where field voles are abundant in the United Kingdom may pose a risk of A. phagocytophilum infection because (i) field voles, the most abundant terrestrial mammal in the United Kingdom, may be a competent reservoir; (ii) the field voles are hosts for both nymphal and larval ixodid ticks so they could support endemic cycles of A. phagocytophilum; and (iii) they are hosts for nidicolous I. trianguliceps, which may alone maintain endemic cycles, and exophilic I. ricinus ticks, which could act as a bridge vector and transmit infections to humans and domesticated animals.
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Affiliation(s)
- K J Bown
- Department of Veterinary Pathology, University of Liverpool, Liverpool, UK.
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Ogden NH, Bigras-Poulin M, O'callaghan CJ, Barker IK, Kurtenbach K, Lindsay LR, Charron DF. Vector seasonality, host infection dynamics and fitness of pathogens transmitted by the tick Ixodes scapularis. Parasitology 2006; 134:209-27. [PMID: 17032476 DOI: 10.1017/s0031182006001417] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 06/22/2006] [Accepted: 07/18/2006] [Indexed: 11/06/2022]
Abstract
Fitness of tick-borne pathogens may be determined by the degree to which their infection dynamics in vertebrate hosts permits transmission cycles if infective and uninfected tick stages are active at different times of the year. To investigate this hypothesis we developed a simulation model that integrates the transmission pattern imposed by seasonally asynchronous nymphal and larval Ixodes scapularis ticks in northeastern North America, with a model of infection in white-footed mice (Peromyscus leucopus) reservoir hosts, using the bacteria Borrelia burgdorferi and Anaplasma phagocytophilum as examples. In simulations, survival of microparasites, their sensitivity to reduced rodent and tick abundance, and to 'dilution' by a reservoir-incompetent host depended on traits that allowed (i) highly efficient transmission from acutely-infected hosts, (ii) long-lived acute or 'carrier' host infections, and/or (iii) transmission amongst co-feeding ticks. Minimum values for transmission efficiency to ticks, and duration of host infectivity, necessary for microparasite persistence, were always higher when nymphal and larval ticks were seasonally asynchronous than when these instars were synchronous. Thus, traits influencing duration of host infectivity, transmission efficiency to ticks and co-feeding transmission are likely to be dominant determinants of fitness in I. scapularis-borne microparasites in northeastern North America due to abiotic forcings influencing I. scapularis seasonality.
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Affiliation(s)
- N H Ogden
- Faculté de médecine vétérinaire, Université de Montréal, C.P. 5000, Saint-Hyacinthe, QC, J2S 7C6, Canada.
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Ogden NH, Trudel L, Artsob H, Barker IK, Beauchamp G, Charron DF, Drebot MA, Galloway TD, O'Handley R, Thompson RA, Lindsay LR. Ixodes scapularis ticks collected by passive surveillance in Canada: analysis of geographic distribution and infection with Lyme borreliosis agent Borrelia burgdorferi. J Med Entomol 2006; 43:600-9. [PMID: 16739422 DOI: 10.1603/0022-2585(2006)43[600:istcbp]2.0.co;2] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Passive surveillance for the occurrence of the tick Ixodes scapularis Say (1821) and their infection with the Lyme borreliosis spirochaetes Borrelia burgdorferi s.l. has taken place in Canada since early 1990. Ticks have been submitted from members of the public, veterinarians, and medical practitioners to provincial, federal, and university laboratories for identification, and the data have been collated and B. burgdorferi detected at the National Microbiology Laboratory. The locations of collection of 2,319 submitted I. scapularis were mapped, and we investigated potential risk factors for I. scapularis occurrence (in Quebec as a case study) by using regression analysis and spatial statistics. Ticks were submitted from all provinces east of Alberta, most from areas where resident I. scapularis populations are unknown. Most were adult ticks and were collected in spring and autumn. In southern Québec, risk factors for tick occurrence were lower latitude and remote-sensed indices for land cover with woodland. B. burgdorferi infection, identified by conventional and molecular methods, was detected in 12.5% of 1,816 ticks, including 10.1% of the 256 ticks that were collected from humans and tested. Our study suggests that B. burgdorferi-infected I. scapularis can be found over a wide geographic range in Canada, although most may be adventitious ticks carried from endemic areas in the United States and Canada by migrating birds. The risk of Lyme borreliosis in Canada may therefore be mostly low but more geographically widespread than previously suspected.
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Affiliation(s)
- N H Ogden
- Groupe de Recherche en Epidémiologie des Zoonoses et Santé Publique, Université de Montréal, Québec, Canada J2S 7C6.
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Ogden NH, Trudel L, Artsob H, Barker IK, Beauchamp G, Charron DF, Drebot MA, Galloway TD, O'Handley R, Thompson RA, Lindsay LR. Ixodes scapularis ticks collected by passive surveillance in Canada: analysis of geographic distribution and infection with Lyme borreliosis agent Borrelia burgdorferi. J Med Entomol 2006; 43:600-609. [PMID: 16739422 DOI: 10.1093/jmedent/43.3.600] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Passive surveillance for the occurrence of the tick Ixodes scapularis Say (1821) and their infection with the Lyme borreliosis spirochaetes Borrelia burgdorferi s.l. has taken place in Canada since early 1990. Ticks have been submitted from members of the public, veterinarians, and medical practitioners to provincial, federal, and university laboratories for identification, and the data have been collated and B. burgdorferi detected at the National Microbiology Laboratory. The locations of collection of 2,319 submitted I. scapularis were mapped, and we investigated potential risk factors for I. scapularis occurrence (in Quebec as a case study) by using regression analysis and spatial statistics. Ticks were submitted from all provinces east of Alberta, most from areas where resident I. scapularis populations are unknown. Most were adult ticks and were collected in spring and autumn. In southern Québec, risk factors for tick occurrence were lower latitude and remote-sensed indices for land cover with woodland. B. burgdorferi infection, identified by conventional and molecular methods, was detected in 12.5% of 1,816 ticks, including 10.1% of the 256 ticks that were collected from humans and tested. Our study suggests that B. burgdorferi-infected I. scapularis can be found over a wide geographic range in Canada, although most may be adventitious ticks carried from endemic areas in the United States and Canada by migrating birds. The risk of Lyme borreliosis in Canada may therefore be mostly low but more geographically widespread than previously suspected.
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Affiliation(s)
- N H Ogden
- Groupe de Recherche en Epidémiologie des Zoonoses et Santé Publique, Université de Montréal, Québec, Canada J2S 7C6.
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Swai ES, French NP, Karimuribo ED, Fitzpatrick JL, Bryant MJ, Brown PE, Ogden NH. Spatial and management factors associated with exposure of smallholder dairy cattle in Tanzania to tick-borne pathogens. Int J Parasitol 2006; 35:1085-96. [PMID: 16023121 DOI: 10.1016/j.ijpara.2005.04.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Revised: 04/20/2005] [Accepted: 04/21/2005] [Indexed: 10/25/2022]
Abstract
A cross-sectional study of serum antibody responses of cattle to tick-borne pathogens (Theileria parva, Theileria mutans,Anaplasma marginale, Babesia bigemina and Babesia bovis) was conducted on smallholder dairy farms in Tanga and Iringa Regions of Tanzania. Seroprevalence was highest for T. parva (48% in Iringa and 23% in Tanga) and B. bigemina (43% in Iringa and 27% in Tanga) and lowest for B. bovis (12% in Iringa and 6% in Tanga). We use spatial and non-spatial models, fitted using classical and Bayesian methods, to explore risk factors associated with seroprevalence. These include both fixed effects (age, grazing history and breeding status) and random effects (farm and local spatial effects). In both regions, seroprevalence for all tick-borne pathogens increased significantly with age. Animals pasture grazed in the 3 months prior to the start of the sampling period were significantly more likely to be seropositive for Theileria spp. and Babesia spp. Pasture grazed animals were more likely to be seropositive than zero-grazed animals for A. marginale, but the relationship was weaker than that observed for the other four pathogens. This study did not detect any significant differences in seroprevalence associated with other management-related variables, including the method or frequency of acaricide application. After adjusting for age, there was weak evidence of localised (<5 km) spatial correlation in exposure to some of the tick borne diseases. However, this was small compared with the 'farm-effect', suggesting that risk factors specific to the farm were more important than those common to the local neighbourhood. Many animals were seropositive for more than one pathogen and the correlation between exposure to the different pathogens remained after adjusting for the identified risk factors. Identifying the determinants of exposure to multiple tick-borne pathogens and characterizing local variation in risk will assist in the development of more effective control strategies for smallholder dairy farms.
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Affiliation(s)
- E S Swai
- Faculty of Veterinary Medicine, Sokoine University of Agriculture, Morogoro, Tanzania
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Karimuribo ED, Fitzpatrick JL, Bell CE, Swai ES, Kambarage DM, Ogden NH, Bryant MJ, French NP. Clinical and subclinical mastitis in smallholder dairy farms in Tanzania: Risk, intervention and knowledge transfer. Prev Vet Med 2006; 74:84-98. [PMID: 16488030 DOI: 10.1016/j.prevetmed.2006.01.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In a cross-sectional study of 400 randomly selected smallholder dairy farms in the Tanga and Iringa regions of Tanzania, 14.2% (95% confidence interval (CI)=11.6-17.3) of cows had developed clinical mastitis during the previous year. The point prevalence of subclinical mastitis, defined as a quarter positive by the California Mastitis Test (CMT) or by bacteriological culture, was 46.2% (95% CI=43.6-48.8) and 24.3% (95% CI=22.2-26.6), respectively. In a longitudinal disease study in Iringa, the incidence of clinical mastitis was 31.7 cases per 100 cow-years. A randomised intervention trial indicated that intramammary antibiotics significantly reduced the proportion of bacteriologically positive quarters in the short-term (14 days post-infusion) but teat dipping had no detectable effect on bacteriological infection and CMT positive quarters. Other risk and protective factors were identified from both the cross-sectional and longitudinal included animals with Boran breeding (odds ratio (OR)=3.40, 95% CI=1.00-11.57, P<0.05 for clinical mastitis, and OR=3.51, 95% CI=1.29-9.55, P<0.01 for a CMT positive quarter), while the practice of residual calf suckling was protective for a bacteriologically positive quarter (OR=0.63, 95% CI=0.48-0.81, P<or=0.001) and for a CMT positive quarter (OR=0.69, 95% CI=0.63-0.75, P<0.001). A mastitis training course for farmers and extension officers was held, and the knowledge gained and use of different methods of dissemination were assessed over time. In a subsequent randomised controlled trial, there were strong associations between knowledge gained and both the individual question asked and the combination of dissemination methods (village meeting, video and handout) used. This study demonstrated that both clinical and subclinical mastitis is common in smallholder dairying in Tanzania, and that some of the risk and protective factors for mastitis can be addressed by practical management of dairy cows following effective knowledge transfer.
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Affiliation(s)
- E D Karimuribo
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, P.O. Box 3021, Morogoro, Tanzania.
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Ogden NH, Barker IK, Beauchamp G, Brazeau S, Charron DF, Maarouf A, Morshed MG, O'Callaghan CJ, Thompson RA, Waltner-Toews D, Waltner-Toews M, Lindsay LR. Investigation of ground level and remote-sensed data for habitat classification and prediction of survival of Ixodes scapularis in habitats of southeastern Canada. J Med Entomol 2006; 43:403-414. [PMID: 16619627 DOI: 10.1093/jmedent/43.2.403] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In southeastern Canada, most populations of Ixodes scapularis Say, the Lyme disease vector, occur in Carolinian forests. Climate change projections suggest a northward range expansion of I. scapularis this century, but it is unclear whether more northerly habitats are suitable for I. scapularis survival. In this study, we assessed the suitability of woodlands of the Lower Great Lakes/St. Lawrence Plain region for I. scapularis by comparing tick egg survival in four different woodlands. Woodlands where I. scapularis are established, and sand dune where I. scapularis do not survive, served as positive and negative control sites, respectively. At two woodland sites, egg survival was the same as at the positive control site, but at two of the sites survival was significantly less than either the positive control site, or one of the other test sites. Egg survival in all woodland sites was significantly higher than in the sand dune site. Ground level habitat classification discriminated among woodlands in which tick survival differed. The likelihood that I. scapularis populations could persist in the different habitats, as deduced using a population model of I. scapularis, was significantly associated with variations in Landsat 7 ETM+ data (normalized difference vegetation index [NDVI] and Tasselled Cap indices). The NDVI index predicted habitat suitability at Long Point, Ontario, with high sensitivity but moderate specificity. Our study suggests that I. scapularis populations could establish in more northerly woodland types than those in which they currently exist. Suitable habitats may be detected by ground-level habitat classification, and remote-sensed data may assist this process.
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Affiliation(s)
- N H Ogden
- Groupe de Recherche en Epidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Que., Canada
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Ogden NH, Barker IK, Beauchamp G, Brazeau S, Charron DF, Maarouf A, Morshed MG, O'Callaghan CJ, Thompson RA, Waltner-Toews D, Waltner-Toews M, Lindsay LR. Investigation of ground level and remote-sensed data for habitat classification and prediction of survival of Ixodes scapularis in habitats of southeastern Canada. J Med Entomol 2006; 43:403-14. [PMID: 16619627 DOI: 10.1603/0022-2585(2006)043[0403:ioglar]2.0.co;2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In southeastern Canada, most populations of Ixodes scapularis Say, the Lyme disease vector, occur in Carolinian forests. Climate change projections suggest a northward range expansion of I. scapularis this century, but it is unclear whether more northerly habitats are suitable for I. scapularis survival. In this study, we assessed the suitability of woodlands of the Lower Great Lakes/St. Lawrence Plain region for I. scapularis by comparing tick egg survival in four different woodlands. Woodlands where I. scapularis are established, and sand dune where I. scapularis do not survive, served as positive and negative control sites, respectively. At two woodland sites, egg survival was the same as at the positive control site, but at two of the sites survival was significantly less than either the positive control site, or one of the other test sites. Egg survival in all woodland sites was significantly higher than in the sand dune site. Ground level habitat classification discriminated among woodlands in which tick survival differed. The likelihood that I. scapularis populations could persist in the different habitats, as deduced using a population model of I. scapularis, was significantly associated with variations in Landsat 7 ETM+ data (normalized difference vegetation index [NDVI] and Tasselled Cap indices). The NDVI index predicted habitat suitability at Long Point, Ontario, with high sensitivity but moderate specificity. Our study suggests that I. scapularis populations could establish in more northerly woodland types than those in which they currently exist. Suitable habitats may be detected by ground-level habitat classification, and remote-sensed data may assist this process.
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Affiliation(s)
- N H Ogden
- Groupe de Recherche en Epidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Que., Canada
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Stuen S, Casey ANJ, Woldehiwet Z, French NP, Ogden NH. Detection by the polymerase chain reaction of Anaplasma phagocytophilum in tissues of persistently infected sheep. J Comp Pathol 2005; 134:101-4. [PMID: 16330039 DOI: 10.1016/j.jcpa.2005.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 06/22/2005] [Indexed: 11/18/2022]
Abstract
To investigate the reservoir tissues of the tick-borne bacterium Anaplasma phagocytophilum in persistently infected sheep, six 6-month-old lambs were infected with a field isolate of the bacterium and maintained under tick-free conditions. At one and two weeks post-infection, A. phagocytophilum was detected in the peripheral blood of all lambs by examining May-Grünwald Giemsa-stained blood smears for classical intra-neutrophil inclusions, and by an A. phagocytophilum-specific nested PCR. After euthanasia at 3 months post-inoculation, peripheral blood and numerous tissue samples were collected from each lamb. DNA extracted from these samples was then subjected to PCR. All blood samples were PCR-negative but three lambs had PCR-positive tissues including intestinal wall and lymph nodes, thymus, bone marrow, kidney and bladder wall. The widespread nature of PCR-positive tissues suggested that circulatory cells may form the reservoir cells for A. phagocytophilum infection in carrier sheep, rather than lymphoid tissues as in rodents. PCR-positive tissue and blood samples were strikingly fewer in the experimentally infected sheep than reported earlier in tick-exposed carrier sheep under field conditions. It seems possible that tick infestation amplifies A. phagocytophilum infections in carrier sheep to a degree that enables tick transmission to occur.
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Affiliation(s)
- S Stuen
- Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, Sandnes, Norway
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Swai ES, Karimuribo ED, Ogden NH, French NP, Fitzpatrick JL, Bryant MJ, Kambarage DM. Seroprevalence Estimation and Risk Factors for A. marginale on Smallholder Dairy Farms in Tanzania. Trop Anim Health Prod 2005; 37:599-610. [PMID: 16619876 DOI: 10.1007/s11250-005-4307-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A cross-sectional serological survey of A. marginale was conducted on 200 randomly selected smallholder farms in each of the Tanga and Iringa Regions of Tanzania between January and April 1999. Sera, from dairy cattle of all ages, sexes and breeds were tested for antibodies against A. marginale using an indirect enzyme-linked immunosorbent assay. Antibodies to A. marginale were present in cattle throughout the study areas and the overall prevalence was 20% for Tanga and 37% for Iringa. The forces of infection based on the age seroprevalence profile were estimated at 8 for Tanga and 15 for Iringa per 100 cattle years-risk, respectively. In both regions, seroprevalence increased with age (beta = 0.01 and 0.017 per year of age, p < 0.005, in Tanga and Iringa, respectively). Older animals in Iringa were significantly and negatively associated with decreased seropositivity (beta = -0.002, p = 0.0029). Further results of logistic regression models reveal that geographic location of animals in Tanga was associated with seropositivity (odds ratio (OR) = 2.94, p = 0.005, for Tanga Rural and OR = 2.38, p = 0.066, for Muheza). Animals acquired as a gift in Iringa had higher odds for seropositivity than brought-in cattle (OR = 2.44, p = 0.005). Our study has identified and quantified some key risk factors that can guide planners devising disease control strategies.
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Affiliation(s)
- E S Swai
- Veterinary Investigation Centre, Arusha
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Ogden NH, Maarouf A, Barker IK, Bigras-Poulin M, Lindsay LR, Morshed MG, O'callaghan CJ, Ramay F, Waltner-Toews D, Charron DF. Climate change and the potential for range expansion of the Lyme disease vector Ixodes scapularis in Canada. Int J Parasitol 2005; 36:63-70. [PMID: 16229849 DOI: 10.1016/j.ijpara.2005.08.016] [Citation(s) in RCA: 259] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Revised: 08/25/2005] [Accepted: 08/26/2005] [Indexed: 11/23/2022]
Abstract
We used an Ixodes scapularis population model to investigate potential northward spread of the tick associated with climate change. Annual degree-days >0 degrees C limits for I. scapularis establishment, obtained from tick population model simulations, were mapped using temperatures projected for the 2020s, 2050s and 2080s by two Global Climate Models (the Canadian CGCM2 and the UK HadCM3) for two greenhouse gas emission scenario enforcings 'A2'and 'B2' of the Intergovernmental Panel on Climate Change. Under scenario 'A2' using either climate model, the theoretical range for I. scapularis establishment moved northwards by approximately 200 km by the 2020s and 1000 km by the 2080s. Reductions in emissions (scenario 'B2') had little effect on projected range expansion up to the 2050s, but the range expansion projected to occur between the 2050s and 2080s was less than that under scenario 'A2'. When the tick population model was driven by projected annual temperature cycles (obtained using CGCM2 under scenario 'A2'), tick abundance almost doubled by the 2020s at the current northern limit of I. scapularis, suggesting that the threshold numbers of immigrating ticks needed to establish new populations will fall during the coming decades. The projected degrees of theoretical range expansion and increased tick survival by the 2020s, suggest that actual range expansion of I. scapularis may be detectable within the next two decades. Seasonal tick activity under climate change scenarios was consistent with maintenance of endemic cycles of the Lyme disease agent in newly established tick populations. The geographic range of I. scapularis-borne zoonoses may, therefore, expand significantly northwards as a consequence of climate change this century.
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Affiliation(s)
- N H Ogden
- Groupe de Recherche en Epidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Que., Canada.
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Bell CE, French NP, Karimuribo E, Ogden NH, Bryant MJ, Swai EM, Kambarage DM, Fitzpatrick JL. The effects of different knowledge-dissemination interventions on the mastitis knowledge of Tanzanian smallholder dairy farmers. Prev Vet Med 2005; 72:237-51. [PMID: 16154215 DOI: 10.1016/j.prevetmed.2005.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Revised: 03/10/2005] [Accepted: 05/03/2005] [Indexed: 10/25/2022]
Abstract
We developed three different knowledge-dissemination methods for educating Tanzanian smallholder farmers about mastitis in their dairy cattle. The effectiveness of these methods (and their combinations) was evaluated and quantified using a randomised controlled trial and multilevel statistical modelling. To our knowledge, this is the first study that has used such techniques to evaluate the effectiveness of different knowledge-dissemination interventions for adult learning in developing countries. Five different combinations of knowledge-dissemination method were compared: 'diagrammatic handout' ('HO'), 'village meeting' ('VM'), 'village meeting and video' ('VM+V'), 'village meeting and diagrammatic handout' ('VM+HO') and 'village meeting, video and diagrammatic handout' ('VM+V+HO'). Smallholder dairy farmers were exposed to only one of these interventions, and the effectiveness of each was compared to a control ('C') group, who received no intervention. The mastitis knowledge of each farmer (n=256) was evaluated by questionnaire both pre- and post-dissemination. Generalised linear mixed models were used to evaluate the effectiveness of the different interventions. The outcome variable considered was the probability of volunteering correct responses to mastitis questions post-dissemination, with 'village' and 'farmer' considered as random effects in the model. Results showed that all five interventions, 'HO' (odds ratio (OR)=3.50, 95% confidence intervals (CI)=3.10, 3.96), 'VM+V+HO' (OR=3.34, 95% CI=2.94, 3.78), 'VM+HO' (OR=3.28, 95% CI=2.90, 3.71), 'VM+V' (OR=3.22, 95% CI=2.84, 3.64) and 'VM' (OR=2.61, 95% CI=2.31, 2.95), were significantly (p<0.0001) more effective at disseminating mastitis knowledge than no intervention. In addition, the 'VM' method was less effective at disseminating mastitis knowledge than other interventions. Combinations of methods showed no advantage over the diagrammatic handout alone. Other explanatory variables with significant positive associations on mastitis knowledge included education to secondary school level or higher, and having previously learned about mastitis by reading pamphlets or attendance at an animal-health course.
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Affiliation(s)
- C E Bell
- Institute of Comparative Medicine, Division of Animal Production and Public Health, University of Glasgow Veterinary School, Bearsden Road, Glasgow G61 1QH, UK.
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Swai ES, Bryant MJ, Karimuribo ED, French NP, Ogden NH, Fitzpatrick JL, Kambarage DM. A Cross-sectional Study of Reproductive Performance of Smallholder Dairy Cows in Coastal Tanzania. Trop Anim Health Prod 2005; 37:513-25. [PMID: 16248223 DOI: 10.1007/s11250-005-1218-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A retrospective cross-sectional study was conducted on 200 randomly selected smallholder farms from a mixed dairy farming system in Tanga, Tanzania, between January and April 1999. We estimated the frequency and determinants of long calving interval (LCI), retention of fetal membrane (RFM), dystocia, and abortion in smallholder crossbred cattle and explored birth trends. The mean calving interval was 500 days and birth rate was 65 per 100 cow-years. Dystocia was reported to affect 58% of calvings, and 17.2% of animals suffered RFM. Using mixed effect models, the variables associated with LCI, RFM and dystocia were breed, level of exotic blood and condition score. Zebu breeding was associated with LCI (odds ratio (OR) = 2.3, p = 0.041) and Friesian breeding with lower odds for RF (OR = 0.26, p = 0.020). Animals with higher levels of exotic blood had lower odds for evidence of dystocia (OR = 0.45, p = 0.021). Evidence of dystocia was significantly associated with poor condition score (p = -1.10, p = 0.001). Our observations suggest that LCIs are common in smallholder dairy farms in this region and a likely source of economic loss. Dystocia, RFM, poor condition score and mineral deficiency were common problems and were possibly linked to LCI.
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Affiliation(s)
- E S Swai
- Veterinary Investigation Centre, Arusha, Tanzania
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Ogden NH, Bigras-Poulin M, O'Callaghan CJ, Barker IK, Lindsay LR, Maarouf A, Smoyer-Tomic KE, Waltner-Toews D, Charron D. A dynamic population model to investigate effects of climate on geographic range and seasonality of the tick Ixodes scapularis. Int J Parasitol 2005; 35:375-89. [PMID: 15777914 DOI: 10.1016/j.ijpara.2004.12.013] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2004] [Revised: 12/17/2004] [Accepted: 12/20/2004] [Indexed: 11/28/2022]
Abstract
A dynamic population model of Ixodes scapularis, the vector of a number of tick-borne zoonoses in North America, was developed to simulate effects of temperature on tick survival and seasonality. Tick development rates were modelled as temperature-dependent time delays, calculated using mean monthly normal temperature data from specific meteorological stations. Temperature also influenced host-finding success in the model. Using data from stations near endemic populations of I. scapularis, the model reached repeatable, stable, cyclical equilibria with seasonal activity of different instars being very close to that observed in the field. In simulations run using data from meteorological stations in central and eastern Canada, the maximum equilibrium numbers of ticks declined the further north was the station location, and simulated populations died out at more northerly stations. Tick die-out at northern latitudes was due to a steady increase in mortality of all life stages with decreasing temperature rather than a specific threshold event in phenology of one life stage. By linear regression we investigated mean annual numbers of degree-days >0 degrees C (DD>0 degrees C) as a readily mapped index of the temperature conditions at the meteorological stations providing temperature data for the model. Maximum numbers of ticks at equilibrium were strongly associated with the mean DD>0 degrees C (r2>0.96, P<0.001), when the Province of origin of the meteorological station was accounted for (Quebec>Ontario, beta=103, P<0.001). The intercepts of the regression models provided theoretical limits for the establishment of I. scapularis in Canada. Maps of these limits suggested that the range of southeast Canada where temperature conditions are currently suitable for the tick, is much wider than the existing distribution of I. scapularis, implying that there is potential for spread. Future applications of the model in investigating climate change effects on I. scapularis are discussed.
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Affiliation(s)
- N H Ogden
- Groupe de Recherche en Epidémiologie des Zoonoses et Santé Publique, Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, CP 5000, Saint-Hyacinthe, Qué., Canada J2S 7C6.
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Swai ES, French NP, Beauchamp G, Fitzpatrick JL, Bryant MJ, Kambarage D, Ogden NH. A longitudinal study of sero-conversion to tick-borne pathogens in smallholder dairy youngstock in Tanzania. Vet Parasitol 2005; 131:129-37. [PMID: 15936149 DOI: 10.1016/j.vetpar.2005.04.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Revised: 04/25/2005] [Accepted: 04/27/2005] [Indexed: 11/16/2022]
Abstract
A longitudinal study of sero-conversion of youngstock to the tick-borne pathogens Theileria parva, T. mutans, Anaplasma marginale, Babesia bigemina and B. bovis was conducted over two years on smallholder dairy farms in Tanga region, Tanzania. There was evidence of maternal antibodies to all tick-borne pathogens in animals less than 18 weeks of age. Seroprevalence increased as expected with age in animals older than this but seroprevalence profiles underestimated the force of infection due to waning antibody levels between samplings. By the end of the 2-year study, less than 50% of study animals had seroconverted to each of the tick-borne pathogens investigated, consistent with the low levels of tick attachment observed on the study animals. Some associations between seroconversion to tick-borne pathogens, and counts of their known tick vectors on the animals, were identified as expected. However, some were not, suggesting that counts of some tick species may act as an index of rates of attachment of other vector species. Variation in acaricide treatment frequencies was not associated with variations in tick-borne pathogen seroprevalence suggesting that acaricides may be used more frequently than necessary on many farms. Most animals were zero-grazed, a management system associated with a significantly lower likelihood that animals seroconverted to any tick-borne pathogen except A. marginale. Seroprevalence varied locally with farm location (particularly for Babesia spp.) but was not well predicted by indices of ecological conditions. Our findings suggest that attempts to achieve a state of 'endemic stability' for tick-borne pathogens may be unreasonable on the smallholder dairy farms studied but reductions in the frequency of use of acaricides may be possible following prospective studies of effects on mortality and morbidity due to tick-borne pathogens.
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Affiliation(s)
- E S Swai
- Tanga Dairy Development Programme, Tanga, Tanzania
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Ogden NH, Swai E, Beauchamp G, Karimuribo E, Fitzpatrick JL, Bryant MJ, Kambarage D, French NP. Risk factors for tick attachment to smallholder dairy cattle in Tanzania. Prev Vet Med 2004; 67:157-70. [PMID: 15737429 DOI: 10.1016/j.prevetmed.2004.10.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Revised: 09/24/2004] [Accepted: 10/14/2004] [Indexed: 11/28/2022]
Abstract
A cross-sectional study was conducted in Tanga and Iringa regions of Tanzania, and a longitudinal study in Tanga, to investigate tick-control methods and other factors influencing tick attachment to the cattle of smallholder dairy farms. Most farmers reported applying acaricides at intervals of 1-2 weeks, most used acaricides that require on-farm dilution and most farmers incorrectly diluted the acaricides. Rhipicephalus appendiculatus and Boophilus spp. ticks were those most-frequently encountered on the cattle, but few cattle carried ticks of any species (only 13 and 4.6% of tick counts of the cattle yielded adult R. appendiculatus and Boophilus spp., respectively). Animals were more likely to carry one or more adult Boophilus spp. ticks if they also carried one or more R. appendiculatus adults (OR=14.4, CI=9.2, 22.5). The use of pour-on acaricides was associated with lower odds that animals carried a R. appendiculatus tick (OR=0.29, CI=0.18, 0.49) but higher odds that they carried a Boophilus spp. tick (OR=2.48, CI=1.55, 3.97). Animals >4 months old and those with a recent history of grazing had higher odds of carrying either a R. appendiculatus (ORs=3.41 and 2.58, CIs=2.34, 4.98 and 1.80, 3.71), or a Boophilus spp. tick (ORs=5.70 and 2.18, CIs=2.34, 4.98 and 1.49. 3.25), but zero-grazing management did not prevent ticks attaching to cattle even when combined with high-frequency acaricide treatments. The odds that animals carried ticks varied amongst the agro-ecological zones (AEZs) and administrative districts where the farms were situated-but there was still considerable residual variation in tick infestation at the farm level.
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Affiliation(s)
- N H Ogden
- Groupe de Recherche en Epidémiologie et Santé Publique, Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal C.P. 5000, Saint-Hyacinthe, Que. J2S 7C6, Canada.
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Swai ES, Karimuribo ED, French NP, Ogden NH, Fitzpatrick J, Kambarage D, Bryant MJ. Cross-sectional estimation of Babesia bovis antibody prevalence in cattle in two contrasting dairying areas in Tanzania. ACTA ACUST UNITED AC 2004;71:211-7. [PMID: 15580770 DOI: 10.4102/ojvr.v71i3.262] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
The crude prevalence of antibodies to Babesia bovis infection in cattle was estimated by serology using indirect ELISA during the period January to April, 1999. Sera were obtained from 1 395 dairy cattle (of all ages, sexes and breeds) on smallholder farms, the majority being kept under a zero grazing regime. The crude prevalence of antibodies to Babesia bovis was 6 % for Tanga and 12% for Iringa. The forces of infection based on the age sero-prevalence profile, were estimated at six for Iringa and four for Tanga per 100 cattle years-risk, respectively. Using random effect logistic regression as the analytical method, the factors (variables) of age, source of animals and geographic location were hypothesised to be associated with sero-positivity of Babesia bovis in the two regions.
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Affiliation(s)
- E S Swai
- Veterinary Investigation Centre, Box 1068 Arusha, Tanzania.
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Ogden NH, Lindsay LR, Beauchamp G, Charron D, Maarouf A, O'Callaghan CJ, Waltner-Toews D, Barker IK. Investigation of relationships between temperature and developmental rates of tick Ixodes scapularis (Acari: Ixodidae) in the laboratory and field. J Med Entomol 2004; 41:622-633. [PMID: 15311453 DOI: 10.1603/0022-2585-41.4.622] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Relationships between temperature and preoviposition, preeclosion, and premolt developmental periods for the tick Ixodes scapularis Say were investigated by holding field-collected ticks in the laboratory at temperatures of 0 to 32 degrees C at constant daylength. The duration of these developmental periods decreased significantly with increasing temperature. Host of origin, prior storage at 4 degrees C, and season of collection of the ticks were also significantly associated with variations in the duration of the preoviposition period. For each developmental stage, the effect of temperature on development rate was best described as a power relationship. Laboratory-derived relationships were used to predict dates for molting, oviposition, and eclosion of engorged larvae and nymphs, engorged adult females and egg masses, respectively, placed in the field during 1989-1992. Predicted dates for oviposition by adult females, eclosion of eggs, and molting of engorged larvae were within 2 wk of the observed dates, and field-observed seasonal activity of questing larvae and nymphs also was predicted well by laboratory data. Molting of engorged nymphs and seasonal activity of questing adult ticks were, however, poorly predicted. Our findings suggest that duration of development in the field, of larvae from engorged adult females, and of nymphs from engorged larvae, may be explained largely by temperature effects alone, whereas emergence of adult I. scapularis from engorged nymphs may depend on temperature-independent diapause phenomena. The significance of these findings for understanding current and future distributions of I. scapularis, and of the pathogens it transmits, is discussed.
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Affiliation(s)
- N H Ogden
- Groupe de Recherche en Epidémiologie et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Québec, Canada.
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Casey ANJ, Birtles RJ, Radford AD, Bown KJ, French NP, Woldehiwet Z, Ogden NH. Groupings of highly similar major surface protein (p44)-encoding paralogues: a potential index of genetic diversity amongst isolates of Anaplasma phagocytophilum. Microbiology (Reading) 2004; 150:727-734. [PMID: 14993322 DOI: 10.1099/mic.0.26648-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Anaplasma phagocytophilum is a tick-borne bacterium that is zoonotic in the USA and southern Europe, but although the bacterium is endemic in the UK, no cases of clinical human disease have yet been detected in that country. Potential genomic differences amongst UK and USA isolates were investigated by comparing partial 16S rRNA gene and p44 paralogue sequences amplified by PCR from 10 UK ruminant or tick isolates, with published sequences from USA isolates. No significant clustering among the isolates was resolved by phylogenetic analysis of alignments containing 16S rRNA gene sequences. The structure of predicted proteins encoded by p44 paralogues, amplified from 81 clones obtained from the UK isolates, was similar to that described previously for paralogues from USA isolates. Paralogue sequences did not obviously cluster by country, host species or isolate, but most paralogues were 30-70 % similar, making meaningful alignments difficult. Some p44 paralogues from different isolates formed clusters of sequences that were more than 90 % similar to one another ('similarity groups'). The paralogues in each cluster were particularly similar in gene regions most likely to code for ligands. In the sample studied, 95 % of the similarity groups comprised paralogues from either USA or UK isolates only and occurred with greater frequency amongst paralogues from USA rather than UK isolates. These findings raise the hypothesis that sequences of paralogues in similarity groups may provide an index of adaptation of different 'strains' of A. phagocytophilum to specific reservoir hosts in different geographical locations, and any associations with infectivity for different species including humans.
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Affiliation(s)
- A N J Casey
- Department of Veterinary Preclinical Science, University of Liverpool, Brownlow Hill and Crown Street, Liverpool L69 7ZJ, UK
| | - R J Birtles
- Department of Veterinary Pathology, University of Liverpool, Leahurst, Neston, South Wirral CH64 7TE, UK
| | - A D Radford
- Department of Veterinary Clinical Science, University of Liverpool, Leahurst, Neston, South Wirral CH64 7TE, UK
| | - K J Bown
- Department of Veterinary Preclinical Science, University of Liverpool, Brownlow Hill and Crown Street, Liverpool L69 7ZJ, UK
| | - N P French
- Department of Veterinary Clinical Science, University of Liverpool, Leahurst, Neston, South Wirral CH64 7TE, UK
| | - Z Woldehiwet
- Department of Veterinary Pathology, University of Liverpool, Leahurst, Neston, South Wirral CH64 7TE, UK
| | - N H Ogden
- Department of Veterinary Preclinical Science, University of Liverpool, Brownlow Hill and Crown Street, Liverpool L69 7ZJ, UK
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Ogden NH, Casey ANJ, Woldehiwet Z, French NP. Transmission of Anaplasma phagocytophilum to Ixodes ricinus ticks from sheep in the acute and post-acute phases of infection. Infect Immun 2003; 71:2071-8. [PMID: 12654828 PMCID: PMC152096 DOI: 10.1128/iai.71.4.2071-2078.2003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2002] [Revised: 12/14/2002] [Accepted: 01/02/2003] [Indexed: 11/20/2022] Open
Abstract
A total of 60 sheep were exposed to Anaplasma phagocytophilum infection on an enclosed area of Ixodes ricinus-infested pasture in North Wales, United Kingdom, and rapidly acquired acute A. phagocytophilum infections detectable by PCR and blood smear examination. Of the ticks that had engorged in the previous instar on infected sheep, 52% of adult ticks and 28% of nymphs were PCR positive; a significant, 10-fold increase in prevalence compared to that of ticks that engorged on sheep preinfection was observed (P = 0.015). The likelihood that ticks were PCR positive, after feeding on the sheep and molting to the next instar, increased marginally with increasing numbers of infected neutrophils per milliliter of blood of their sheep host (P = 0.068) and increased significantly when they were collected from sheep carrying higher numbers of adult female ticks (P = 0.017), but increasing numbers of feeding nymphs had a significant negative effect on transmission (P = 0.049). The numbers of circulating neutrophils and of infected neutrophils also varied significantly with the numbers of ticks feeding on the sheep when the blood was collected. Our study suggests that ruminants are efficient reservoirs of A. phagocytophilum during the acute and post-acute phases of infection. The risk of ruminant-derived infections may, however, be strongly affected by variations in tick densities, which may influence transmission from acutely infected animals via effects on the numbers of infected cells in the blood and possibly by within-skin modulation of infection.
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Affiliation(s)
- N H Ogden
- Department of Veterinary Preclinical Sciences, University of Liverpool, Liverpool L69 7ZJ, UK.
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Ogden NH, Gwakisa P, Swai E, French NP, Fitzpatrick J, Kambarage D, Bryant M. Evaluation of PCR to detect Theileria parva in field-collected tick and bovine samples in Tanzania. Vet Parasitol 2003; 112:177-83. [PMID: 12591193 DOI: 10.1016/s0304-4017(02)00448-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The ability of PCR to detect infections of Theileria parva, the cause of East Coast Fever, in field-collected tick and bovine samples from Tanzania was evaluated. PCR-detected infection prevalence was high (15/20, 75%) in unfed adult Rhipicephalus appendiculatus ticks that fed as nymphs on an acutely-infected calf, but low (22/836, 2.6%) in unfed adult R. appendiculatus collected from field sites in Tanzania. Tick infection prevalence was comparable to that in previous studies that used salivary gland staining to detect T. parva infection in field-collected host-seeking ticks. Of 282 naturally-exposed zebu calves, seven had PCR-positive buffy coat samples prior to detection of Theileria spp. parasites in stained buffy coat cells or lymph node biopsies. Evidence of Theileria spp. infections was detected in stained smears of lymph node biopsies from 109 calves (38.6%) and buffy coat samples from 81 (28.7%), while buffy coat samples from 66 (23.4%) were PCR-positive for T. parva. Implications of these findings for the sensitivity and specificity of the PCR are discussed.
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Affiliation(s)
- N H Ogden
- Department of Veterinary Preclinical Science, Faculty of Veterinary Science, University of Liverpool, Brownlow Hill & Crown Street, L69 7ZJ, Liverpool, UK.
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Abstract
The recently described method of centrifugation with iodixanol for the rapid separation of human plasma lipoproteins was adapted to separate bovine plasma lipoproteins. Density gradients were generated by mixing plasma with iodixanol 12% (w/v), followed by centrifugation at 350,000 g and 16 degrees C for 3 h 10 min in a vertical rotor. Gradients were unloaded dense-end first into 10 fractions. Human very low density lipoprotein (VLDL; density < 1.011 g/ml), low density lipoprotein (LDL; density = 1.016-1.039 g/ml) and high density lipoprotein (HDL; density = 1.039-1.090 g/ml) were resolved well at densities considerably lower than those traditionally reported in salt gradients. In gradients generated from 12% iodixanol, bovine LDL and HDL exhibited even lower densities (1.016-1.028 and 1.016-1.048 g/ml, respectively) with all lipoproteins occurring at the lower density region of the gradient. In contrast, density gradients generated from layers of equal volumes of 6% and 12% iodixanol readily separated bovine HDL from VLDL, whilst LDL still overlapped with HDL. The latter accounts for >80% of all bovine lipoproteins and exists as two populations, namely light and heavy HDL. Gradients generated from two layers of iodixanol recovered bovine HDL in five fractions. The hypercholesterolaemia associated with lactation resulted in a modest shift in the profile of HDL cholesterol towards lipoprotein particles of lower density (light HDL). Significant between-farm differences were also detected in the density profiles of bovine plasma cholesterol. This new method is suitable for use in research and diagnosis in relation to lipoprotein metabolism disorders in cows.
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Affiliation(s)
- R S Gardner
- Department of Veterinary Clinical Science and Animal Husbandry, University of Liverpool, Liverpool, UK
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