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Diarra AZ, Kelly P, Davoust B, Parola P. Tick-Borne Diseases of Humans and Animals in West Africa. Pathogens 2023; 12:1276. [PMID: 38003741 PMCID: PMC10675719 DOI: 10.3390/pathogens12111276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 11/26/2023] Open
Abstract
Ticks are a significant group of arthropod vectors that transmit a large variety of pathogens responsible for human and animal diseases worldwide. Ticks are the second biggest transmitters of vector-borne diseases, behind mosquitoes. However, in West Africa, there is often only limited knowledge of tick-borne diseases. With the scarcity of appropriate diagnostic services, the prevalence of tick-borne diseases is generally underestimated in humans. In this review, we provide an update on tick-borne pathogens reported in people, animals and ticks in West Africa by microscopic, immunological and molecular methods. A systematic search was conducted in PubMed and Google Scholar. The selection criteria included all studies conducted in West Africa reporting the presence of Rickettsia, Borrelia, Anaplasma, Ehrlichia, Bartonella, Coxiella burnetii, Theileria, Babesia, Hepatozoon and Crimean-Congo haemorrhagic fever viruses in humans, animals or ticks. Our intention is to raise awareness of tick-borne diseases amongst human and animal health workers in West Africa, and also physicians working with tourists who have travelled to the region.
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Affiliation(s)
- Adama Zan Diarra
- IHU-Méditerranée Infection, 13005 Marseille, France; (A.Z.D.); (B.D.)
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, 13005 Marseille, France
| | - Patrick Kelly
- Ross University School of Veterinary Medicine, Basseterre P.O. Box 334, Saint Kitts and Nevis;
| | - Bernard Davoust
- IHU-Méditerranée Infection, 13005 Marseille, France; (A.Z.D.); (B.D.)
- Aix Marseille Univ, IRD, AP-HM, MEPHI, 13005 Marseille, France
| | - Philippe Parola
- IHU-Méditerranée Infection, 13005 Marseille, France; (A.Z.D.); (B.D.)
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, 13005 Marseille, France
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Collins M, Ngetich C, Owido M, Getange D, Harris R, Bargul JL, Bodha B, Njoroge D, Muloi D, Martins DJ, Villinger J, Githaka N, Baylis M, Fèvre EM, Kanduma E, Younan M, Bell-Sakyi L. Detection of Antibodies to Ehrlichia spp. in Dromedary Camels and Co-Grazing Sheep in Northern Kenya Using an Ehrlichia ruminantium Polyclonal Competitive ELISA. Microorganisms 2022; 10:microorganisms10050916. [PMID: 35630361 PMCID: PMC9144424 DOI: 10.3390/microorganisms10050916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 04/22/2022] [Accepted: 04/26/2022] [Indexed: 12/13/2022] Open
Abstract
A disease with clinical and post-mortem presentation similar to those seen in heartwater, a tick-borne disease of domestic and wild ruminants caused by the intracellular bacterium Ehrlichia ruminantium, was first reported in dromedary camels in Kenya in 2016; investigations carried out at the time to determine the cause were inconclusive. In the present study, we screened sera from Kenyan camels collected before (2015) and after (2020) the 2016 disease outbreak for antibodies to Ehrlichia spp. using an E. ruminantium polyclonal competitive ELISA (PC-ELISA). Median antibody levels were significantly higher (p < 0.0001) amongst camels originating from areas where the heartwater-like disease was reported than from disease-free areas, for animals sampled in both 2015 and 2020. Overall median seropositivity was higher in camels sampled in 2015 than in 2020, which could have been due to higher mean age in the former group. Camels that were PCR-positive for Candidatus Ehrlichia regneryi had significantly lower (p = 0.03) median antibody levels than PCR-negative camels. Our results indicate that Kenyan camels are frequently exposed to E. ruminantium from an early age, E. ruminantium was unlikely to have been the sole cause of the outbreak of heartwater-like disease; and Ca. E. regneryi does not appreciably cross-react with E. ruminantium in the PC-ELISA.
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Affiliation(s)
- Marisol Collins
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
| | - Collins Ngetich
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | - Milton Owido
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | - Dennis Getange
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi P.O. Box 62000-00200, Kenya; (D.G.); (J.L.B.)
| | - Robert Harris
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
| | - Joel L. Bargul
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi P.O. Box 62000-00200, Kenya; (D.G.); (J.L.B.)
- International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya;
| | - Boku Bodha
- Directorate of Veterinary Services, County Government of Marsabit, Marsabit P.O. Box 384-60500, Kenya;
| | - Daniel Njoroge
- Department of Biochemistry and Molecular Biology, Faculty of Science, Egerton University, Njoro P.O. Box 536-20115, Kenya;
| | - Dishon Muloi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | | | - Jandouwe Villinger
- International Centre of Insect Physiology and Ecology, Nairobi P.O. Box 30772-00100, Kenya;
| | - Naftaly Githaka
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | - Matthew Baylis
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
| | - Eric M. Fèvre
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya; (C.N.); (M.O.); (N.G.)
| | - Esther Kanduma
- Department of Biochemistry, Faculty of Science and Technology, University of Nairobi, Nairobi P.O. Box 30197-00100, Kenya;
| | - Mario Younan
- Food and Agriculture Organisation of the United Nations (FAO), Programme and Operational Support to Syria Crisis, UN Cross-Border Hub, Gaziantep 27010, Turkey;
| | - Lesley Bell-Sakyi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (R.H.); (D.M.); (M.B.); (E.M.F.)
- Correspondence:
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Getange D, Bargul JL, Kanduma E, Collins M, Bodha B, Denge D, Chiuya T, Githaka N, Younan M, Fèvre EM, Bell-Sakyi L, Villinger J. Ticks and Tick-Borne Pathogens Associated with Dromedary Camels ( Camelus dromedarius) in Northern Kenya. Microorganisms 2021; 9:1414. [PMID: 34209060 PMCID: PMC8306667 DOI: 10.3390/microorganisms9071414] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 06/21/2021] [Accepted: 06/22/2021] [Indexed: 12/17/2022] Open
Abstract
Ticks and tick-borne pathogens (TBPs) are major constraints to camel health and production, yet epidemiological data on their diversity and impact on dromedary camels remain limited. We surveyed the diversity of ticks and TBPs associated with camels and co-grazing sheep at 12 sites in Marsabit County, northern Kenya. We screened blood and ticks (858 pools) from 296 camels and 77 sheep for bacterial and protozoan TBPs by high-resolution melting analysis and sequencing of PCR products. Hyalomma (75.7%), Amblyomma (17.6%) and Rhipicephalus (6.7%) spp. ticks were morphologically identified and confirmed by molecular analyses. We detected TBP DNA in 80.1% of blood samples from 296 healthy camels. "Candidatus Anaplasma camelii", "Candidatus Ehrlichia regneryi" and Coxiella burnetii were detected in both camels and associated ticks, and Ehrlichia chaffeensis, Rickettsia africae, Rickettsia aeschlimannii and Coxiella endosymbionts were detected in camel ticks. We also detected Ehrlichia ruminantium, which is responsible for heartwater disease in ruminants, in Amblyomma ticks infesting camels and sheep and in sheep blood, indicating its endemicity in Marsabit. Our findings also suggest that camels and/or the ticks infesting them are disease reservoirs of zoonotic Q fever (C. burnetii), ehrlichiosis (E. chaffeensis) and rickettsiosis (R. africae), which pose public health threats to pastoralist communities.
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Affiliation(s)
- Dennis Getange
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (D.G.); (T.C.)
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi P.O. Box 62000-00200, Kenya
| | - Joel L. Bargul
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (D.G.); (T.C.)
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi P.O. Box 62000-00200, Kenya
| | - Esther Kanduma
- Department of Biochemistry, School of Medicine, University of Nairobi, Nairobi P.O. Box 30197-00100, Kenya;
| | - Marisol Collins
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (E.M.F.); (L.B.-S.)
| | - Boku Bodha
- Directorate of Veterinary Services, County Government of Marsabit, Marsabit P.O. Box 384-60500, Kenya; (B.B.); (D.D.)
| | - Diba Denge
- Directorate of Veterinary Services, County Government of Marsabit, Marsabit P.O. Box 384-60500, Kenya; (B.B.); (D.D.)
| | - Tatenda Chiuya
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (D.G.); (T.C.)
| | - Naftaly Githaka
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya;
| | - Mario Younan
- Food and Agriculture Organization of the United Nations (FAO), Programme & Operational Support to Syria Crisis, UN cross-border hub, Gaziantep 27010, Turkey;
| | - Eric M. Fèvre
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (E.M.F.); (L.B.-S.)
- International Livestock Research Institute, Nairobi P.O. Box 30709-00100, Kenya;
| | - Lesley Bell-Sakyi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK; (M.C.); (E.M.F.); (L.B.-S.)
| | - Jandouwe Villinger
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (D.G.); (T.C.)
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Campbell Z, Coleman P, Guest A, Kushwaha P, Ramuthivheli T, Osebe T, Perry B, Salt J. Prioritizing smallholder animal health needs in East Africa, West Africa, and South Asia using three approaches: Literature review, expert workshops, and practitioner surveys. Prev Vet Med 2021; 189:105279. [PMID: 33581421 PMCID: PMC8024747 DOI: 10.1016/j.prevetmed.2021.105279] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 12/18/2020] [Accepted: 01/18/2021] [Indexed: 12/15/2022]
Abstract
Managing the health needs of livestock contributes to reducing poverty and improving the livelihoods of smallholder and pastoralist livestock keepers globally. Animal health practitioners, producers, policymakers, and researchers all must prioritize how to mobilize limited resources. This study employed three approaches to prioritize animal health needs in East and West Africa and South Asia to identify diseases and syndromes that impact livestock keepers. The approaches were a) systematic literature review, b) a series of expert workshops, and c) a practitioner survey of veterinarians and para-veterinary professionals. The top constraints that emerged from all three approaches include endo/ ectoparasites, foot and mouth disease, brucellosis, peste des petits ruminants, Newcastle disease, and avian influenza. Expert workshops additionally identified contagious caprine pleuropneumonia, contagious bovine pleuropneumonia, mastitis, and reproductive disorders as constraints not emphasized in the literature review. Practitioner survey results additionally identified nutrition as a constraint for smallholder dairy and pastoralist small ruminant production. Experts attending the workshops agreed most constraints can be managed using existing veterinary technologies and best husbandry practices, which supports a shift away from focusing on individual diseases and new technologies towards addressing systemic challenges that limit access to veterinary services and inputs. Few research studies focused on incidence/ prevalence of disease and impact, suggesting better incorporation of socio-economic impact measures in future research would better represent the interests of livestock keepers.
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Affiliation(s)
- Zoë Campbell
- International Livestock Research Institute (ILRI), P.O. Box 30709, Nairobi, 00100, Kenya.
| | - Paul Coleman
- H20 Venture Partners, 33-35 George Street, Oxford, OX1 2AY, United Kingdom
| | - Andrea Guest
- H20 Venture Partners, 33-35 George Street, Oxford, OX1 2AY, United Kingdom
| | - Peetambar Kushwaha
- GALVmed Asia Office, Unit 118 & 120 B, Splendor Forum, Plot No 3, Jasola District Centre, Jasola, New Delhi, 110025, India
| | - Thembinkosi Ramuthivheli
- GALVmed Africa Office, International Livestock Research Institute (ILRI), Swing One, Naivasha Road, Nairobi, Kenya
| | - Tom Osebe
- GALVmed Africa Office, International Livestock Research Institute (ILRI), Swing One, Naivasha Road, Nairobi, Kenya
| | - Brian Perry
- Nuffield College of Clinical Medicine, University of Oxford, United Kingdom; College of Medicine and Veterinary Medicine, University of Edinburgh, Arthurstone House, Meigle, Blairgowrie, PH12 8QW, Scotland, United Kingdom
| | - Jeremy Salt
- GALVmed UK Office, Doherty Building, Pentlands Science Park, Bush Loan, Penicuik Edinburgh, EH26 0PZ, Scotland, United Kingdom
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Teshale S, Geysen D, Ameni G, Dorny P, Berkvens D. Survey of Anaplasma phagocytophilum and Anaplasma sp. 'Omatjenne' infection in cattle in Africa with special reference to Ethiopia. Parasit Vectors 2018. [PMID: 29523210 PMCID: PMC5845267 DOI: 10.1186/s13071-018-2633-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background As evidence of the infection of domestic animals by Anaplasma phagocytophilum and Anaplasma sp. ‘Omatjenne’ is presently becoming available, understanding the epidemiological and ecological significance of infection is important to quantify the clinical and socio-economic impact of the diseases they cause. Methods The first aim of this study was to analyse the occurrence of A. phagocytophilum and Anaplasma sp. ‘Omatjenne’ in cattle samples collected from selected African countries using a polymerase chain reaction and restriction enzyme fragment length polymorphism. Secondly, this study was aimed at the molecular identification of Ehrlichia spp. and Anaplasma spp. infection in ruminants raised under different production systems in selected sites in central Ethiopia. Results In total, 695 samples from cattle in six African countries were analysed. Overall, 45 positive results were obtained for Anaplasma sp. ‘Omatjenne’ (6.47%) and 19 for A. phagocytophilum (2.73%). Anaplasma sp. ‘Omatjenne’ was detected in all countries except Tanzania while A. phagocytophilum was detected only in samples from Ethiopia. The proportion of samples tested positive for Anaplasma sp. ‘Omatjenne’ ranged from 1.2% in Morocco to 16% in Rwanda. The occurrence of both agents is now confirmed in African cattle. For the survey in Ethiopia a semi-nested 16S rDNA polymerase chain reaction followed by restriction fragment length polymorphism was used for the identification of Ehrlichia spp. and Anaplasma spp. in blood samples. Randomly selected samples were also analysed by pCS20 polymerase chain reaction for the detection of E. ruminantium. Positive results were obtained for E. ruminantium and five species of Anaplasma including a zoonotic species. To our knowledge, this is the first report of infection of domestic ruminants with A. phagocytophilum, A. ovis and Anaplasma sp. ‘Omatjenne’ in Ethiopia. Conclusion The present study showed widespread occurrence of Anaplasma sp. 'Omatijenne' in African cattle and five Anaplasma species in Ethiopia.
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Affiliation(s)
- Sori Teshale
- Addis Ababa University, College of Veterinary Medicine and Agriculture, Bishoftu, Ethiopia. .,Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. .,Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium.
| | - Dirk Geysen
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Gobena Ameni
- Addis Ababa University, Akililu Lemma Institute of Pathobiology, Addis Ababa, Ethiopia
| | - Pierre Dorny
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.,Ghent University, Faculty of Bio-engineering Sciences, Ghent, Belgium
| | - Dirk Berkvens
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.,Ghent University, Faculty of Bio-engineering Sciences, Ghent, Belgium
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Faburay B, Jongejan F, Taoufik A, Ceesay A, Geysen D. Genetic diversity of Ehrlichia ruminantium in Amblyomma variegatum ticks and small ruminants in The Gambia determined by restriction fragment profile analysis. Vet Microbiol 2008; 126:189-99. [PMID: 17646061 DOI: 10.1016/j.vetmic.2007.06.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2007] [Revised: 05/29/2007] [Accepted: 06/14/2007] [Indexed: 11/28/2022]
Abstract
Understanding genetic diversity of Ehrlichia ruminantium in host and vector populations is an important prerequisite to controlling heartwater by vaccination in traditional livestock systems in sub-Saharan Africa. We carried out a study in two phases: (i) evaluating the usefulness of the PCR-RFLP assay based on the map1 coding sequence of E. ruminantium as a discriminatory tool to characterise genetic diversity, (ii) applying the technique to field samples from Amblyomma variegatum ticks and small ruminants to characterise genotypic diversity of the organism in three main agroecological zones of The Gambia, Sudano-Guinean (SG), Western Sudano-Sahelian (WSS) and Eastern Sudano-Sahelian (ESS). Restriction fragment length polymorphisms were observed among different strains of E. ruminantium supporting the usefulness of the PCR-RFLP technique for studying genetic diversity of the organism. Restriction enzyme map1 profile analysis indicated the presence in The Gambia of multiple genotypes (at least 11) of E. ruminantium with sites in the WSS and SG zones showing comparatively high number of diverse genotypes. Profiles similar to the Kerr Seringe genotype (DQ333230) showed the highest distribution frequency, being present at sites in all three agroecological zones, thereby making the strain a suitable candidate for further characterisation in cross-protection studies. An additional three genotypes showed relatively high distribution frequency and were present in all three zones making them equally important for isolation and subsequent characterisation. The study demonstrated the occurrence of mixed infections with E. ruminantium genotypes in ruminants and ticks.
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Affiliation(s)
- Bonto Faburay
- International Trypanotolerance Centre, PMB 14, Banjul, The Gambia.
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Immunisation of sheep against heartwater in The Gambia using inactivated and attenuated Ehrlichia ruminantium vaccines. Vaccine 2007; 25:7939-47. [PMID: 17920167 DOI: 10.1016/j.vaccine.2007.09.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 08/29/2007] [Accepted: 09/02/2007] [Indexed: 11/28/2022]
Abstract
Heartwater (cowdriosis) is a disease of ruminants caused by a rickettsial pathogen Ehrlichia ruminantium and transmitted by ticks of the genus Amblyomma. The purpose of this work was to evaluate the protective efficacies of inactivated and attenuated vaccines to protect sheep against heartwater in The Gambia. An inactivated vaccine, prepared from E. ruminantium (Gardel stock), and a live attenuated vaccine from E. ruminantium (Senegal stock), were evaluated in two independent on-station trials. A local stock of E. ruminantium (Kerr Seringe) was used as challenge material. Inactivated and live attenuated vaccines provided 43% and 100% protection, respectively, against virulent needle challenge. In a subsequent field trial, the attenuated vaccine protected 75% of sheep against virulent tick challenge, which was fatal for all control sheep. Quantification by real-time PCR showed that an immunising dose of approximately 23,000 attenuated E. ruminantium organisms was sufficient. Moreover, restriction fragment length polymorphism (RFLP) analysis indicated that the local Kerr Seringe genotype caused mortality amongst control sheep, whereas fatalities in the vaccinated group could be attributed to a different genotype.
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Longitudinal monitoring of Ehrlichia ruminantium infection in Gambian lambs and kids by pCS20 PCR and MAP1-B ELISA. BMC Infect Dis 2007; 7:85. [PMID: 17662144 PMCID: PMC1949406 DOI: 10.1186/1471-2334-7-85] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 07/27/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The epidemiology of E. ruminantium infection in extensively managed young animals is not adequately understood. Thus in this study, we monitored the onset (age at first infection) and kinetics of E. ruminantium infection and antibody response in extensively managed newborn lambs and kids at three sites in The Gambia. METHODS We used a nested pCS20 PCR and MAP1-B ELISA in a longitudinal study to monitor the onset (age at first infection) and kinetics of E. ruminantium infection and antibody response respectively, in 77 newborn lambs and kids under a traditional husbandry system at three sites (Kerr Seringe, Keneba, Bansang) in The Gambia where heartwater is known to occur. The animals were monitored for field tick infestation and the comparative performance of the two assays in detecting E. ruminantium infection was also assessed. RESULTS The infection rate detected by pCS20 PCR varied between 8.6% and 54.8% over the 162-day study period. Nineteen per cent of the animals in week 1 post-partum tested positive by pCS20 PCR with half of these infections (7/14) detected in the first 3 days after birth, suggesting that transmission other than by tick feeding had played a role. The earliest detectable A. variegatum infestation in the animals occurred in week 16 after birth. Antibodies detected by MAP1-B ELISA also varied, between 11.5% and 90%. Although there is considerable evidence that this assay can detect false positives and due to this and other reasons serology is not a reliable predictor of infection at least for heartwater. In contrast to the pCS20 PCR, the serological assay detected the highest proportion of positive animals in week 1 with a gradual decline in seropositivity with increasing age. The pCS20 PCR detected higher E. ruminantium prevalence in the animals with increasing age and both the Spearman's rank test (rs = -0.1512; P = 0.003) and kappa statistic (-0.091 to 0.223) showed a low degree of agreement between the two assays. CONCLUSION The use of pCS20 PCR supported by transmission studies and clinical data could provide more accurate information on heartwater epidemiology in endemic areas and single-occasion testing of an animal may not reveal its true infection status. The view is supported because both the vector and vertical transmission may play a vital role in the epidemiology of heartwater in young small ruminants; the age range of 4 and 12 weeks corresponds to the period of increased susceptibility to heartwater in traditionally managed small ruminants.
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Faburay B, Geysen D, Munstermann S, Taoufik A, Postigo M, Jongejan F. Molecular detection of Ehrlichia ruminantium infection in Amblyomma variegatum ticks in The Gambia. EXPERIMENTAL & APPLIED ACAROLOGY 2007; 42:61-74. [PMID: 17476576 DOI: 10.1007/s10493-007-9073-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 04/09/2007] [Indexed: 05/15/2023]
Abstract
In West Africa, losses due to heartwater disease are not known because the incidence/prevalence has not been well studied or documented. To develop a diagnostic tool for molecular epidemiology, three PCR-based diagnostic assays, a nested pCS20 PCR, a nested map1 PCR and a nested reverse line blot (RLB) hybridization assay, were evaluated to determine their ability to detect infection in vector ticks, by applying them simultaneously to A. variegatum field ticks to detect Ehrlichia ruminantium, the causative agent of heartwater. The nested pCS20 PCR assay which amplified the pCS20 gene fragment showed the highest detection performance with a detection rate of 16.6%; the nested map1 PCR, which amplified the gene encoding the major antigenic protein1 (map1 gene) showed a detection rate of 11% and the RLB, based on the 16S rDNA sequence of anaplasma and ehrlichial species, detected 6.2%. The RLB, in addition, demonstrated molecular evidence of Ehrlichia ovina, Anaplasma marginale and Anaplasma ovis infections in The Gambia. Subsequently, the pCS20 assay was applied to study the prevalence and distribution of E. ruminantium tick infection rates at different sites in five divisions of The Gambia. The rates of infection in the country ranged from 1.6% to 15.1% with higher prevalences detected at sites in the westerly divisions (Western, Lower River and North Bank; range 8.3-15.1%) than in the easterly divisions (Central River and Upper River; range 1.6-7.5%). This study demonstrated a gradient in the distribution of heartwater disease risk for susceptible livestock in The Gambia which factor must be considered in the overall design of future upgrading programmes.
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Affiliation(s)
- B Faburay
- International Trypanotolerance Centre, PMB 14, Banjul, The Gambia.
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Faburay B, Munstermann S, Geysen D, Bell-Sakyi L, Ceesay A, Bodaan C, Jongejan F. Point seroprevalence survey of Ehrlichia ruminantium infection in small ruminants in The Gambia. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2005; 12:508-12. [PMID: 15817758 PMCID: PMC1074385 DOI: 10.1128/cdli.12.4.508-512.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Using the MAP1-B enzyme-linked immunosorbent assay, we tested 1,318 serum samples collected from sheep and goats at 28 sites in the five divisions of The Gambia to determine the Ehrlichia ruminantium seroprevalence rates and to assess the risk for heartwater. About half (51.6%) of 639 sheep were positive, with seroprevalence rates per site varying between 6.9% and 100%. The highest seroprevalence was detected in the western part of the country (88.1% in the Western Division and 62.1% in the Lower River Division). Sheep in the two easterly divisions (Central River and Upper River divisions) showed the lowest seroprevalence of 29.3% and 32.4%, respectively, while those in the North Bank Division showed an intermediate prevalence of 40.6%. In goats, less than one-third (30.3%) of 679 animals tested were positive. The highest seroprevalence was detected in goats in the North Bank Division (59%) and Western Division (44.1%). Goats in the Lower River Division showed an intermediate level of 21.9%, whereas the lowest rates were found in the eastern part of the country (4.8% in the Central River Division and 2.3% in the Upper River Division). At nearly all sites, seroprevalence rates were higher in sheep than in goats. The results show a gradient of increasing heartwater risk for susceptible small ruminants from the east to the west of The Gambia. These findings need to be taken into consideration when future livestock-upgrading programs are implemented.
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Affiliation(s)
- Bonto Faburay
- International Trypanotolerance Centre, PMB 14, Banjul, The Gambia.
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Bell-Sakyi L, Koney EBM, Dogbey O, Walker AR. Incidence and prevalence of tick-borne haemoparasites in domestic ruminants in Ghana. Vet Parasitol 2005; 124:25-42. [PMID: 15350659 DOI: 10.1016/j.vetpar.2004.05.027] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2004] [Accepted: 05/13/2004] [Indexed: 11/22/2022]
Abstract
Giemsa-stained thin blood smears prepared monthly from cattle, sheep and goats in the Greater Accra region of Ghana between May 1994 and December 1996 were examined for presence of tick-borne haemoparasites. The majority of animals were less than 2 months old at the start of the survey. Monthly and cumulative incidences are presented of Anaplasma sp., Babesia bigemina, Borrelia sp., Eperythrozoon sp., Theileria mutans and Theileria velifera in cattle, Anaplasma sp., Borrelia sp., and Theileria sp. in sheep, and Anaplasma sp. in goats. T. mutans was the commonest parasite in cattle, with 100% incidence in calves by 10 months of age, and Anaplasma was commonest in small ruminants. The relative prevalence of these haemoparasites in blood smears from cattle, sheep and goats sampled on a single occasion at sites in all 10 regions of Ghana was found to be similar, though actual infection rates were lower. Packed cell volume (PCV) measurements from the sampled animals are also presented; no seasonal trends were evident in the PCV of the cattle, sheep and goats sampled monthly. In animals sampled on a single occasion, mean PCV was significantly higher in cattle and sheep without detectable haemoparasite infection, and in cattle was lowest in animals positive for both Babesia and Anaplasma, while there was no difference in mean PCV levels between parasitised and non-parasitised goats.
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Affiliation(s)
- L Bell-Sakyi
- Accra Veterinary Laboratory, Veterinary Services Department, Ministry of Food and Agriculture, PO Box M161, Accra, Ghana.
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Koney EBM, Dogbey O, Walker AR, Bell-Sakyi L. Ehrlichia ruminantium seroprevalence in domestic ruminants in Ghana. II. Point prevalence survey. Vet Microbiol 2004; 103:183-93. [PMID: 15504589 DOI: 10.1016/j.vetmic.2004.02.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2003] [Revised: 02/03/2004] [Accepted: 02/13/2004] [Indexed: 11/29/2022]
Abstract
Serum samples collected on a single occasion from cattle, sheep and goats at sites in all 10 regions of Ghana were tested for antibodies to Ehrlichia (previously Cowdria) ruminantium, the causative agent of heartwater, by polyclonal competitive ELISA (PC-ELISA). The survey revealed the presence of heartwater-exposed ruminants throughout the country, with local seroprevalence up to 100%. Seronegative, and therefore presumably susceptible, animals were also present in all regions, in some areas in numbers high enough to indicate local endemic instability. Overall seroprevalences in cattle, sheep and goats were 61, 51 and 28% respectively, and were generally higher in the northern part of the country and lower in the forest zone. Amongst animals over 1 year old, two thirds of cattle and sheep, and around one third of goats throughout the country had been exposed to E. ruminantium. In the north, seroprevalence in sheep sampled with and without cattle was similar, whereas in the south seroconversion rates in sheep were significantly higher in areas where cattle were present.
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Affiliation(s)
- E B M Koney
- Veterinary Services Department, Ministry of Food and Agriculture, P.O. Box M161, Accra, Ghana
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