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Tun STT, Min MC, Aguas R, Fornace K, Htoo GN, White LJ, Parker DM. Human movement patterns of farmers and forest workers from the Thailand-Myanmar border. Wellcome Open Res 2023; 6:148. [PMID: 37990719 PMCID: PMC10660292 DOI: 10.12688/wellcomeopenres.16784.2] [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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2023] [Indexed: 11/23/2023] Open
Abstract
Background: Human travel patterns play an important role in infectious disease epidemiology and ecology. Movement into geographic spaces with high transmission can lead to increased risk of acquiring infections. Pathogens can also be distributed across the landscape via human travel. Most fine scale studies of human travel patterns have been done in urban settings in wealthy nations. Research into human travel patterns in rural areas of low- and middle-income nations are useful for understanding the human components of epidemiological systems for malaria or other diseases of the rural poor. The goal of this research was to assess the feasibility of using GPS loggers to empirically measure human travel patterns in this setting, as well as to quantify differing travel patterns by age, gender, and seasonality among study participants. Methods: In this pilot study we recruited 50 rural villagers from along the Myanmar-Thailand border to carry GPS loggers for the duration of a year. The GPS loggers were programmed to take a time-stamped reading every 30 minutes. We calculated daily movement ranges and multi-day trips by age and gender. We incorporated remote sensing data to assess patterns of days and nights spent in forested or farm areas, also by age and gender. Results: Our study showed that it is feasible to use GPS devices to measure travel patterns, though we had difficulty recruiting women and management of the project was relatively intensive. We found that older adults traveled farther distances than younger adults and adult males spent more nights in farms or forests. Conclusion: The results of this study suggest that further work along these lines would be feasible in this region. Furthermore, the results from this study are useful for individual-based models of disease transmission and land use.
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Affiliation(s)
- Sai Thein Than Tun
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Myo Chit Min
- Shoklo Malaria Research Unit, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Ricardo Aguas
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Kimberly Fornace
- Centre for Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London, UK
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Gay Nay Htoo
- Shoklo Malaria Research Unit, Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Lisa J. White
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Daniel M. Parker
- Department of Population Health and Disease Prevention, University of California, Irvine, CA, 92697, USA
- Epidemiology and Biostatistics, University of California, Irvine, CA, 92697, USA
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Trujillano F, Garay GJ, Alatrista-Salas H, Byrne I, Nunez-del-Prado M, Chan K, Manrique E, Johnson E, Apollinaire N, Kouame Kouakou P, Oumbouke WA, Tiono AB, Guelbeogo MW, Lines J, Carrasco-Escobar G, Fornace K. Mapping Malaria Vector Habitats in West Africa: Drone Imagery and Deep Learning Analysis for Targeted Vector Surveillance. Remote Sens (Basel) 2023; 15:2775. [PMID: 37324796 PMCID: PMC7614662 DOI: 10.3390/rs15112775] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Disease control programs are needed to identify the breeding sites of mosquitoes, which transmit malaria and other diseases, in order to target interventions and identify environmental risk factors. The increasing availability of very-high-resolution drone data provides new opportunities to find and characterize these vector breeding sites. Within this study, drone images from two malaria-endemic regions in Burkina Faso and Côte d'Ivoire were assembled and labeled using open-source tools. We developed and applied a workflow using region-of-interest-based and deep learning methods to identify land cover types associated with vector breeding sites from very-high-resolution natural color imagery. Analysis methods were assessed using cross-validation and achieved maximum Dice coefficients of 0.68 and 0.75 for vegetated and non-vegetated water bodies, respectively. This classifier consistently identified the presence of other land cover types associated with the breeding sites, obtaining Dice coefficients of 0.88 for tillage and crops, 0.87 for buildings and 0.71 for roads. This study establishes a framework for developing deep learning approaches to identify vector breeding sites and highlights the need to evaluate how results will be used by control programs.
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Affiliation(s)
- Fedra Trujillano
- Health Innovation Laboratory, Institute of Tropical Medicine “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima 15102, Peru
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Gabriel Jimenez Garay
- Health Innovation Laboratory, Institute of Tropical Medicine “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima 15102, Peru
- Department of Engineering and Computer Science, Faculty of Science and Engineering, Sorbonne University, 75005 Paris, France
| | - Hugo Alatrista-Salas
- Escuela de Posgrado Newman, Tacna 23001, Peru
- Science and Engineering School, Pontificia Universidad Católica del Perú (PUCP), Lima 15088, Peru
| | - Isabel Byrne
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Miguel Nunez-del-Prado
- Peru Research, Development and Innovation Center (Peru IDI), Lima 15076, Peru
- The World Bank, Washington, DC 20433, USA
| | - Kallista Chan
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Edgar Manrique
- Health Innovation Laboratory, Institute of Tropical Medicine “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima 15102, Peru
| | - Emilia Johnson
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Nombre Apollinaire
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou 01 BP 2208, Burkina Faso
| | | | - Welbeck A. Oumbouke
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, London L3 5QA, UK
| | - Alfred B. Tiono
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Moussa W. Guelbeogo
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Jo Lines
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Gabriel Carrasco-Escobar
- Health Innovation Laboratory, Institute of Tropical Medicine “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima 15102, Peru
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
| | - Kimberly Fornace
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow G12 8QQ, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore 119077, Singapore
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Johnson E, Campos-Cerqueira M, Jumail A, Yusni ASA, Salgado-Lynn M, Fornace K. Applications and advances in acoustic monitoring for infectious disease epidemiology. Trends Parasitol 2023; 39:386-399. [PMID: 36842917 DOI: 10.1016/j.pt.2023.01.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [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: 10/19/2022] [Revised: 01/19/2023] [Accepted: 01/19/2023] [Indexed: 02/28/2023]
Abstract
Emerging infectious diseases continue to pose a significant burden on global public health, and there is a critical need to better understand transmission dynamics arising at the interface of human activity and wildlife habitats. Passive acoustic monitoring (PAM), more typically applied to questions of biodiversity and conservation, provides an opportunity to collect and analyse audio data in relative real time and at low cost. Acoustic methods are increasingly accessible, with the expansion of cloud-based computing, low-cost hardware, and machine learning approaches. Paired with purposeful experimental design, acoustic data can complement existing surveillance methods and provide a novel toolkit to investigate the key biological parameters and ecological interactions that underpin infectious disease epidemiology.
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Affiliation(s)
- Emilia Johnson
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow G12 8QQ, UK.
| | | | - Amaziasizamoria Jumail
- Danau Girang Field Centre c/o Sabah Wildlife Department, Wisma Muis, Block B, 5th Floor, 88100 Kota Kinabalu, Sabah, Malaysia; Organisms and Environment Division, Cardiff School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK
| | - Ashraft Syazwan Ahmady Yusni
- Danau Girang Field Centre c/o Sabah Wildlife Department, Wisma Muis, Block B, 5th Floor, 88100 Kota Kinabalu, Sabah, Malaysia; Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia
| | - Milena Salgado-Lynn
- Danau Girang Field Centre c/o Sabah Wildlife Department, Wisma Muis, Block B, 5th Floor, 88100 Kota Kinabalu, Sabah, Malaysia; Organisms and Environment Division, Cardiff School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK; Wildlife Health, Genetic and Forensic Laboratory, c/o Sabah Wildlife Department, Wisma Muis, Block B, 5th Floor, 88100 Kota Kinabalu, Sabah
| | - Kimberly Fornace
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow G12 8QQ, UK; Centre for Climate Change and Planetary Health and Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK; Saw Swee Hock School of Public Health, National University of Singapore, Singapore; National University Health System, Singapore 117549, Singapore
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Longet S, Leggio C, Bore JA, Key S, Tipton T, Hall Y, Koundouno FR, Bower H, Bhattacharyya T, Magassouba N, Günther S, Henao-Restrapo AM, Rossman JS, Konde MK, Fornace K, Carroll MW. Influence of Landscape Patterns on Exposure to Lassa Fever Virus, Guinea. Emerg Infect Dis 2023; 29:304-313. [PMID: 36692336 PMCID: PMC9881776 DOI: 10.3201/eid2902.212525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Lassa fever virus (LASV) is the causative agent of Lassa fever, a disease endemic in West Africa. Exploring the relationships between environmental factors and LASV transmission across ecologically diverse regions can provide crucial information for the design of appropriate interventions and disease monitoring. We investigated LASV exposure in 2 ecologically diverse regions of Guinea. Our results showed that exposure to LASV was heterogenous between and within sites. LASV IgG seropositivity was 11.9% (95% CI 9.7%-14.5%) in a coastal study site in Basse-Guinée, but it was 59.6% (95% CI 55.5%-63.5%) in a forested study site located in Guinée Forestière. Seropositivity increased with age in the coastal site. We also found significant associations between exposure risk for LASV and landscape fragmentation in coastal and forested regions. Our study highlights the potential link between environmental change and LASV emergence and the urgent need for research on land management practices that reduce disease risks.
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Carrasco-Escobar G, Moreno M, Fornace K, Herrera-Varela M, Manrique E, Conn JE. The use of drones for mosquito surveillance and control. Parasit Vectors 2022; 15:473. [PMID: 36527116 PMCID: PMC9758801 DOI: 10.1186/s13071-022-05580-5] [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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 11/04/2022] [Indexed: 12/23/2022] Open
Abstract
In recent years, global health security has been threatened by the geographical expansion of vector-borne infectious diseases such as malaria, dengue, yellow fever, Zika and chikungunya. For a range of these vector-borne diseases, an increase in residual (exophagic) transmission together with ecological heterogeneity in everything from weather to local human migration and housing to mosquito species' behaviours presents many challenges to effective mosquito control. The novel use of drones (or uncrewed aerial vehicles) may play a major role in the success of mosquito surveillance and control programmes in the coming decades since the global landscape of mosquito-borne diseases and disease dynamics fluctuates frequently and there could be serious public health consequences if the issues of insecticide resistance and outdoor transmission are not adequately addressed. For controlling both aquatic and adult stages, for several years now remote sensing data have been used together with predictive modelling for risk, incidence and detection of transmission hot spots and landscape profiles in relation to mosquito-borne pathogens. The field of drone-based remote sensing is under continuous change due to new technology development, operation regulations and innovative applications. In this review we outline the opportunities and challenges for integrating drones into vector surveillance (i.e. identification of breeding sites or mapping micro-environmental composition) and control strategies (i.e. applying larval source management activities or deploying genetically modified agents) across the mosquito life-cycle. We present a five-step systematic environmental mapping strategy that we recommend be undertaken in locations where a drone is expected to be used, outline the key considerations for incorporating drone or other Earth Observation data into vector surveillance and provide two case studies of the advantages of using drones equipped with multispectral cameras. In conclusion, recent developments mean that drones can be effective for accurately conducting surveillance, assessing habitat suitability for larval and/or adult mosquitoes and implementing interventions. In addition, we briefly discuss the need to consider permissions, costs, safety/privacy perceptions and community acceptance for deploying drone activities.
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Affiliation(s)
- Gabriel Carrasco-Escobar
- grid.11100.310000 0001 0673 9488Health Innovation Laboratory, Institute of Tropical Medicine “Alexander Von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Peru
- grid.266100.30000 0001 2107 4242School of Public Health, University of California San Diego, La Jolla, USA
| | - Marta Moreno
- grid.8991.90000 0004 0425 469XFaculty of Infectious and Tropical Diseases and Centre for Climate Change and Planetary Health, London School Hygiene and Tropical Medicine, London, UK
| | - Kimberly Fornace
- grid.8991.90000 0004 0425 469XFaculty of Infectious and Tropical Diseases and Centre for Climate Change and Planetary Health, London School Hygiene and Tropical Medicine, London, UK
- grid.8756.c0000 0001 2193 314XSchool of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK
- grid.4280.e0000 0001 2180 6431 Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore, Singapore
| | - Manuela Herrera-Varela
- grid.10689.360000 0001 0286 3748Grupo de Investigación en Entomología, Facultad de Medicina, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Edgar Manrique
- grid.11100.310000 0001 0673 9488Health Innovation Laboratory, Institute of Tropical Medicine “Alexander Von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jan E. Conn
- grid.238491.50000 0004 0367 6866The Wadsworth Center, New York State Department of Health, Albany, NY USA
- grid.189747.40000 0000 9554 2494Department of Biomedical Sciences, School of Public Health, State University of New York, Albany, NY USA
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Chua TH, Manin BO, Fornace K. Life table analysis of Anopheles balabacensis, the primary vector of Plasmodium knowlesi in Sabah, Malaysia. Parasit Vectors 2022; 15:442. [PMID: 36434625 PMCID: PMC9701013 DOI: 10.1186/s13071-022-05552-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 10/07/2022] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Plasmodium knowlesi has become a major public health concern in Sabah, Malaysian Borneo, where it is now the only cause of indigenous malaria. The importance of P. knowlesi has spurred on a series of studies on this parasite, as well as on the biology and ecology of its principal vector, Anopheles balabacensis. However, there remain critical knowledge gaps on the biology of An. balabacensis, such as life history data and life table parameters. To fill these gaps, we conducted a life table study of An. balabacensis in the laboratory. Characterising vector life cycles and survival rates can inform more accurate estimations of the serial interval, the time between two linked cases, which is crucial to understanding and monitoring potentially changing transmission patterns. METHODS Individuals of An. balabacensis were collected in the field in Ranau district, Sabah to establish a laboratory colony. Induced mating was used, and the life history parameters of the progeny were recorded. The age-stage, two-sex life table approach was used in the analysis. The culture conditions in the laboratory were 9 h light:15 h dark, mean temperature 25.7 °C ± 0.05 and relative humidity 75.8% ± 0.31. RESULTS The eggs hatched within 2 days, and the larval stage lasted for 10.5 days in total, with duration of instar stages I, II, III and IV of 2.3, 3.7, 2.3, 2.2 days, respectively. The maximum total fecundity was 729 for one particular female, while the maximum female age-specific mean fecundity (mx) was 142 at age 59 days. The gross reproductive rate or number of offspring per individual was about 102. On average, each female laid 1.81 ± 0.19 (range 1-7) batches of eggs, with 63% of the females producing only one batch; only one female laid six batches, while one other laid seven. Each batch comprised 159 ± 17.1 eggs (range 5-224) and the female ratio of offspring was 0.28 ± 0.06. The intrinsic rate of increase, finite rate of increase, net reproductive rate, mean generation time and doubling time were, respectively, 0.12 ± 0.01 day-1, 1.12 ± 0.01 day-1, 46.2 ± 14.97, 33.02 ± 1.85 and 5.97 days. CONCLUSIONS Both the net reproductive rate and intrinsic rate of increase of An. balabacensis are lower than those of other species in published studies. Our results can be used to improve models of P. knowlesi transmission and to set a baseline for assessing the impacts of environmental change on malaria dynamics. Furthermore, incorporating these population parameters of An. balabacensis into spatial and temporal models on the transmission of P. knowlesi would provide better insight and increase the accuracy of epidemiological forecasting.
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Affiliation(s)
- Tock H. Chua
- grid.265727.30000 0001 0417 0814Department of Pathology and Microbiology, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Sabah, Malaysia
| | - Benny Obrain Manin
- grid.265727.30000 0001 0417 0814Department of Pathology and Microbiology, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Sabah, Malaysia
| | - Kimberly Fornace
- grid.8756.c0000 0001 2193 314XSchool of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK ,grid.4280.e0000 0001 2180 6431Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
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Ruiz Cuenca P, Key S, Lindblade KA, Vythilingam I, Drakeley C, Fornace K. Is there evidence of sustained human-mosquito-human transmission of the zoonotic malaria Plasmodium knowlesi? A systematic literature review. Malar J 2022; 21:89. [PMID: 35300703 PMCID: PMC8929260 DOI: 10.1186/s12936-022-04110-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 11/08/2021] [Accepted: 02/27/2022] [Indexed: 12/03/2022] Open
Abstract
Background The zoonotic malaria parasite Plasmodium knowlesi has emerged across Southeast Asia and is now the main cause of malaria in humans in Malaysia. A critical priority for P. knowlesi surveillance and control is understanding whether transmission is entirely zoonotic or is also occurring through human-mosquito-human transmission. Methods A systematic literature review was performed to evaluate existing evidence which refutes or supports the occurrence of sustained human-mosquito-human transmission of P. knowlesi. Possible evidence categories and study types which would support or refute non-zoonotic transmission were identified and ranked. A literature search was conducted on Medline, EMBASE and Web of Science using a broad search strategy to identify any possible published literature. Results were synthesized using the Synthesis Without Meta-analysis (SWiM) framework, using vote counting to combine the evidence within specific categories. Results Of an initial 7,299 studies screened, 131 studies were included within this review: 87 studies of P. knowlesi prevalence in humans, 14 studies in non-human primates, 13 studies in mosquitoes, and 29 studies with direct evidence refuting or supporting non-zoonotic transmission. Overall, the evidence showed that human-mosquito-human transmission is biologically possible, but there is limited evidence of widespread occurrence in endemic areas. Specific areas of research were identified that require further attention, notably quantitative analyses of potential transmission dynamics, epidemiological and entomological surveys, and ecological studies into the sylvatic cycle of the disease. Conclusion There are key questions about P. knowlesi that remain within the areas of research that require more attention. These questions have significant implications for malaria elimination and eradication programs. This paper considers limited but varied research and provides a methodological framework for assessing the likelihood of different transmission patterns for emerging zoonotic diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04110-z.
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Affiliation(s)
- Pablo Ruiz Cuenca
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster University Medical School, Lancaster, UK. .,Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
| | - Stephanie Key
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Kim A Lindblade
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Indra Vythilingam
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, 50603, Kuala Lumpur, Malaysia
| | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Kimberly Fornace
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
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Fornace K, Manin BO, Matthiopoulos J, Ferguson HM, Drakeley C, Ahmed K, Khoon KT, Ewers RM, Daim S, Chua TH. A protocol for a longitudinal, observational cohort study of infection and exposure to zoonotic and vector-borne diseases across a land-use gradient in Sabah, Malaysian Borneo: a socio-ecological systems approach. Wellcome Open Res 2022; 7:63. [PMID: 35284640 PMCID: PMC8886174 DOI: 10.12688/wellcomeopenres.17678.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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] [Accepted: 02/10/2022] [Indexed: 11/20/2022] Open
Abstract
Introduction. Landscape changes disrupt environmental, social and biological systems, altering pathogen spillover and transmission risks. This study aims to quantify the impact of specific land management practices on spillover and transmission rates of zoonotic and vector-borne diseases within Malaysian Borneo. This protocol describes a cohort study with integrated ecological sampling to assess how deforestation and agricultural practices impact pathogen flow from wildlife and vector populations to human infection and detection by health facilities. This will focus on malaria, dengue and emerging arboviruses (Chikungunya and Zika), vector-borne diseases with varying contributions of simian reservoirs within this setting. Methods. A prospective longitudinal observational cohort study will be established in communities residing or working within the vicinity of the Stability of Altered Forest Ecosystems (SAFE) Project, a landscape gradient within Malaysian Borneo encompassing different plantation and forest types. The primary outcome of this study will be transmission intensity of selected zoonotic and vector-borne diseases, as quantified by changes in pathogen-specific antibody levels. Exposure will be measured using paired population-based serological surveys conducted at the beginning and end of the two-year cohort study. Secondary outcomes will include the distribution and infection rates of Aedes and Anopheles mosquito vectors, human risk behaviours and clinical cases reported to health facilities. Longitudinal data on human behaviour, contact with wildlife and GPS tracking of mobility patterns will be collected throughout the study period. This will be integrated with entomological surveillance to monitor densities and pathogen infection rates of Aedes and Anopheles mosquitoes relative to land cover. Within surrounding health clinics, continuous health facility surveillance will be used to monitor reported infections and febrile illnesses. Models will be developed to assess spillover and transmission rates relative to specific land management practices and evaluate abilities of surveillance systems to capture these risks.
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Affiliation(s)
- Kimberly Fornace
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Benny Obrain Manin
- Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia
| | - Jason Matthiopoulos
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Heather M. Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Kamruddin Ahmed
- Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia
| | - Koay Teng Khoon
- Sabah State Health Department, Ministry of Health, Malaysia, Kota Kinabalu, Malaysia
| | | | - Sylvia Daim
- Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia
- East Malaysia Zoonotic and Infectious Diseases Society, Kota Kinabalu, Malaysia
| | - Tock Hing Chua
- Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia
- East Malaysia Zoonotic and Infectious Diseases Society, Kota Kinabalu, Malaysia
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Cuenca PR, Key S, Jumail A, Surendra H, Ferguson HM, Drakeley CJ, Fornace K. Epidemiology of the zoonotic malaria Plasmodium knowlesi in changing landscapes. Adv Parasitol 2021; 113:225-286. [PMID: 34620384 DOI: 10.1016/bs.apar.2021.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Within the past two decades, incidence of human cases of the zoonotic malaria Plasmodium knowlesi has increased markedly. P. knowlesi is now the most common cause of human malaria in Malaysia and threatens to undermine malaria control programmes across Southeast Asia. The emergence of zoonotic malaria corresponds to a period of rapid deforestation within this region. These environmental changes impact the distribution and behaviour of the simian hosts, mosquito vector species and human populations, creating new opportunities for P. knowlesi transmission. Here, we review how landscape changes can drive zoonotic disease emergence, examine the extent and causes of these changes across Southeast and identify how these mechanisms may be impacting P. knowlesi dynamics. We review the current spatial epidemiology of reported P. knowlesi infections in people and assess how these demographic and environmental changes may lead to changes in transmission patterns. Finally, we identify opportunities to improve P. knowlesi surveillance and develop targeted ecological interventions within these landscapes.
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Affiliation(s)
- Pablo Ruiz Cuenca
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Stephanie Key
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Henry Surendra
- Eijkman-Oxford Clinical Research Unit, Jakarta, Indonesia; Centre for Tropical Medicine, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Heather M Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Chris J Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Kimberly Fornace
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom; Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Scotland, United Kingdom.
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10
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Tun STT, Min MC, Aguas R, Fornace K, Htoo GN, White LJ, Parker DM. Human movement patterns of farmers and forest workers from the Thailand-Myanmar border. Wellcome Open Res 2021. [DOI: 10.12688/wellcomeopenres.16784.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background: Human travel patterns play an important role in infectious disease epidemiology and ecology. Movement into geographic spaces with high transmission can lead to increased risk of acquiring infections. Pathogens can also be distributed across the landscape via human travel. Most fine scale studies of human travel patterns have been done in urban settings in wealthy nations. Research into human travel patterns in rural areas of low- and middle-income nations are useful for understanding the human components of epidemiological systems for malaria or other diseases of the rural poor. The goal of this research was to assess the feasibility of using GPS loggers to empirically measure human travel patterns in this setting, as well as to quantify differing travel patterns by age, gender, and seasonality. Methods: In this pilot study we recruited 50 rural villagers from along the Myanmar-Thailand border to carry GPS loggers for the duration of a year. The GPS loggers were programmed to take a time-stamped reading every 30 minutes. We calculated daily movement ranges and multi-day trips by age and gender. We incorporated remote sensing data to assess patterns of days and nights spent in forested or farm areas, also by age and gender. Results: Our study showed that it is feasible to use GPS devices to measure travel patterns, though we had difficulty recruiting women and management of the project was relatively intensive. We found that older adults traveled farther distances than younger adults and adult males spent more nights in farms or forests. Conclusion: The results of this study suggest that further work along these lines would be feasible in this region. Furthermore, the results from this study are useful for individual-based models of disease transmission and land use.
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11
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Carrasco-Escobar G, Fornace K, Wong D, Padilla-Huamantinco PG, Saldaña-Lopez JA, Castillo-Meza OE, Caballero-Andrade AE, Manrique E, Ruiz-Cabrejos J, Barboza JL, Rodriguez H, Henostroza G, Gamboa D, Castro MC, Vinetz JM, Llanos-Cuentas A. Open-Source 3D Printable GPS Tracker to Characterize the Role of Human Population Movement on Malaria Epidemiology in River Networks: A Proof-of-Concept Study in the Peruvian Amazon. Front Public Health 2020; 8:526468. [PMID: 33072692 PMCID: PMC7542225 DOI: 10.3389/fpubh.2020.526468] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 08/21/2020] [Indexed: 11/13/2022] Open
Abstract
Human movement affects malaria epidemiology at multiple geographical levels; however, few studies measure the role of human movement in the Amazon Region due to the challenging conditions and cost of movement tracking technologies. We developed an open-source low-cost 3D printable GPS-tracker and used this technology in a cohort study to characterize the role of human population movement in malaria epidemiology in a rural riverine village in the Peruvian Amazon. In this pilot study of 20 participants (mean age = 40 years old), 45,980 GPS coordinates were recorded over 1 month. Characteristic movement patterns were observed relative to the infection status and occupation of the participants. Applying two analytical animal movement ecology methods, utilization distributions (UDs) and integrated step selection functions (iSSF), we showed contrasting environmental selection and space use patterns according to infection status. These data suggested an important role of human movement in the epidemiology of malaria in the Peruvian Amazon due to high connectivity between villages of the same riverine network, suggesting limitations of current community-based control strategies. We additionally demonstrate the utility of this low-cost technology with movement ecology analysis to characterize human movement in resource-poor environments.
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Affiliation(s)
- Gabriel Carrasco-Escobar
- Health Innovation Laboratory, Institute of Tropical Medicine "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru.,Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, United States.,Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Kimberly Fornace
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Daniel Wong
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Pierre G Padilla-Huamantinco
- Health Innovation Laboratory, Institute of Tropical Medicine "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru.,Departamento de Ingenieria, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jose A Saldaña-Lopez
- Departamento de Ingenieria, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Ober E Castillo-Meza
- Departamento de Ingenieria, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Armando E Caballero-Andrade
- Departamento de Ingenieria, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Edgar Manrique
- Health Innovation Laboratory, Institute of Tropical Medicine "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru.,Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jorge Ruiz-Cabrejos
- Health Innovation Laboratory, Institute of Tropical Medicine "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru.,Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jose Luis Barboza
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - German Henostroza
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Dionicia Gamboa
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru.,Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru.,Instituto de Medicinal Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Marcia C Castro
- Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, MA, United States
| | - Joseph M Vinetz
- Instituto de Medicinal Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.,Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, United States
| | - Alejandro Llanos-Cuentas
- Instituto de Medicinal Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.,Facultad de Salud Pública y Administración, Universidad Peruana Cayetano Heredia, Lima, Peru
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12
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van den Hoogen LL, Bareng P, Alves J, Reyes R, Macalinao M, Rodrigues JM, Fernandes JM, Goméz LF, Hall T, Singh SK, Fornace K, Luchavez J, Kitchen A, Chiodini P, Espino F, Tetteh KKA, Stresman G, Sepúlveda N, Drakeley C. Comparison of Commercial ELISA Kits to Confirm the Absence of Transmission in Malaria Elimination Settings. Front Public Health 2020; 8:480. [PMID: 33014975 PMCID: PMC7509087 DOI: 10.3389/fpubh.2020.00480] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [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: 02/28/2020] [Accepted: 07/28/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Antimalarial antibody measurements are useful because they reflect historical and recent exposure to malaria. As such, they may provide additional information to assess ongoing transmission in low endemic or pre-elimination settings where cases are rare. In addition, the absence of antibody responses in certain individuals can indicate the cessation of transmission. Commercial malaria enzyme-linked immunosorbent assays (ELISA) detect antimalarial antibodies and are commonly used to screen blood donations for possible malaria infection. However, there is no standardized test to detect antimalarial antibodies for epidemiological use. Here we compared five commercially available ELISA kits (Trinity Biotech, newbio, DiaPro, Cellabs, and NovaTec) in search of a standardized tool for supporting claims of absence of malaria transmission. For comparison, a research-based (RB) ELISA protocol was performed alongside the commercial kits. Results: The commercial kits were first compared using serum samples from known malaria-unexposed individuals (n = 223) and Toxoplasma-infected individuals (n = 191) to assess specificity and cross-reactivity against non-malaria infections. In addition, 134 samples from ≥10-year-olds collected in a hyperendemic region in the Gambia in the early 1990s were used to assess sensitivity. Three out of five kits showed high sensitivity (90–92%), high specificity (98–99%), low cross-reactivity (0–3%) and were considered user-friendly (Trinity Biotech, newbio and NovaTec). Two of these kits (Trinity Biotech and NovaTec) were taken forward for epidemiological evaluation and results were compared to those using the RB-ELISA. Samples from two pre-elimination settings (Praia, Cape Verde; n = 1,396, and Bataan, the Philippines; n = 1,824) were tested. Serological results from both the Trinity Biotech kit and the RB-ELISA concurred with recent passively detected case counts in both settings. Results from the Trinity Biotech kit reflected a significant decrease in the number of reported cases in Bataan in the 1990s better than the RB-ELISA. Results from the NovaTec kit did not reflect transmission patterns in either setting. Conclusion: The Trinity Biotech commercial ELISA kit was considered reliable for epidemiological use and accurately described transmission patterns in two (previously) malaria endemic settings. The use of this simple and standardized serological tool may aid national control and elimination programs by confirming that regions are free from malaria.
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Affiliation(s)
- Lotus L van den Hoogen
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Paolo Bareng
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Joana Alves
- National Institute of Public Health, Praia, Cape Verde
| | - Ralph Reyes
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Malou Macalinao
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | | | - José M Fernandes
- Faculty of Science and Technology, University of Cape Verde, Praia, Cape Verde
| | - Lara F Goméz
- Department of Natural, Life and Environmental Sciences, Jean Piaget University of Cape Verde, Praia, Cape Verde
| | - Tom Hall
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Susheel K Singh
- Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Department of Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Kimberly Fornace
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jennifer Luchavez
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Alan Kitchen
- NHS Blood and Transplant, London, United Kingdom
| | - Peter Chiodini
- Hospital for Tropical Diseases and London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Fe Espino
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Kevin K A Tetteh
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gillian Stresman
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Nuno Sepúlveda
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom.,Centre of Statistics and Applications, University of Lisbon, Lisbon, Portugal
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
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13
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Brown R, Chua TH, Fornace K, Drakeley C, Vythilingam I, Ferguson HM. Human exposure to zoonotic malaria vectors in village, farm and forest habitats in Sabah, Malaysian Borneo. PLoS Negl Trop Dis 2020; 14:e0008617. [PMID: 32886679 PMCID: PMC7497982 DOI: 10.1371/journal.pntd.0008617] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 09/17/2020] [Accepted: 07/20/2020] [Indexed: 12/27/2022] Open
Abstract
The zoonotic malaria parasite, Plasmodium knowlesi, is now a substantial public health problem in Malaysian Borneo. Current understanding of P. knowlesi vector bionomics and ecology in Sabah comes from a few studies near the epicentre of human cases in one district, Kudat. These have incriminated Anopheles balabacensis as the primary vector, and suggest that human exposure to vector biting is peri-domestic as well as in forest environments. To address the limited understanding of vector ecology and human exposure risk outside of Kudat, we performed wider scale surveillance across four districts in Sabah with confirmed transmission to investigate spatial heterogeneity in vector abundance, diversity and infection rate. Entomological surveillance was carried out six months after a cross-sectional survey of P. knowlesi prevalence in humans throughout the study area; providing an opportunity to investigate associations between entomological indicators and infection. Human-landing catches were performed in peri-domestic, farm and forest sites in 11 villages (3-4 per district) and paired with estimates of human P. knowlesi exposure based on sero-prevalence. Anopheles balabacensis was present in all districts but only 6/11 villages. The mean density of An. balabacensis was relatively low, but significantly higher in farm (0.094/night) and forest (0.082/night) than peri-domestic areas (0.007/night). Only one An. balabacensis (n = 32) was infected with P. knowlesi. Plasmodium knowlesi sero-positivity in people was not associated with An. balabacensis density at the village-level however post hoc analyses indicated the study had limited power to detect a statistical association due low vector density. Wider scale sampling revealed substantial heterogeneity in vector density and distribution between villages and districts. Vector-habitat associations predicted from this larger-scale surveillance differed from those inferred from smaller-scale studies in Kudat; highlighting the importance of local ecological context. Findings highlight potential trade-offs between maximizing temporal versus spatial breadth when designing entomological surveillance; and provide baseline entomological and epidemiological data to inform future studies of entomological risk factors for human P. knowlesi infection.
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Affiliation(s)
- Rebecca Brown
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
| | - Tock H. Chua
- Department of Pathobiology and Medical Diagnostics, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia
| | - Kimberly Fornace
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Indra Vythilingam
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Heather M. Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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14
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Stresman G, Sepúlveda N, Fornace K, Grignard L, Mwesigwa J, Achan J, Miller J, Bridges DJ, Eisele TP, Mosha J, Lorenzo PJ, Macalinao ML, Espino FE, Tadesse F, Stevenson JC, Quispe AM, Siqueira A, Lacerda M, Yeung S, Sovannaroth S, Pothin E, Gallay J, Hamre KE, Young A, Lemoine JF, Chang MA, Phommasone K, Mayxay M, Landier J, Parker DM, Von Seidlein L, Nosten F, Delmas G, Dondorp A, Cameron E, Battle K, Bousema T, Gething P, D'Alessandro U, Drakeley C. Association between the proportion of Plasmodium falciparum and Plasmodium vivax infections detected by passive surveillance and the magnitude of the asymptomatic reservoir in the community: a pooled analysis of paired health facility and community data. Lancet Infect Dis 2020; 20:953-963. [PMID: 32277908 PMCID: PMC7391005 DOI: 10.1016/s1473-3099(20)30059-1] [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] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/23/2020] [Accepted: 01/28/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND Passively collected malaria case data are the foundation for public health decision making. However, because of population-level immunity, infections might not always be sufficiently symptomatic to prompt individuals to seek care. Understanding the proportion of all Plasmodium spp infections expected to be detected by the health system becomes particularly paramount in elimination settings. The aim of this study was to determine the association between the proportion of infections detected and transmission intensity for Plasmodium falciparum and Plasmodium vivax in several global endemic settings. METHODS The proportion of infections detected in routine malaria data, P(Detect), was derived from paired household cross-sectional survey and routinely collected malaria data within health facilities. P(Detect) was estimated using a Bayesian model in 431 clusters spanning the Americas, Africa, and Asia. The association between P(Detect) and malaria prevalence was assessed using log-linear regression models. Changes in P(Detect) over time were evaluated using data from 13 timepoints over 2 years from The Gambia. FINDINGS The median estimated P(Detect) across all clusters was 12·5% (IQR 5·3-25·0) for P falciparum and 10·1% (5·0-18·3) for P vivax and decreased as the estimated log-PCR community prevalence increased (adjusted odds ratio [OR] for P falciparum 0·63, 95% CI 0·57-0·69; adjusted OR for P vivax 0·52, 0·47-0·57). Factors associated with increasing P(Detect) included smaller catchment population size, high transmission season, improved care-seeking behaviour by infected individuals, and recent increases (within the previous year) in transmission intensity. INTERPRETATION The proportion of all infections detected within health systems increases once transmission intensity is sufficiently low. The likely explanation for P falciparum is that reduced exposure to infection leads to lower levels of protective immunity in the population, increasing the likelihood that infected individuals will become symptomatic and seek care. These factors might also be true for P vivax but a better understanding of the transmission biology is needed to attribute likely reasons for the observed trend. In low transmission and pre-elimination settings, enhancing access to care and improvements in care-seeking behaviour of infected individuals will lead to an increased proportion of infections detected in the community and might contribute to accelerating the interruption of transmission. FUNDING Wellcome Trust.
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Affiliation(s)
- Gillian Stresman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK.
| | - Nuno Sepúlveda
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK; Centre of Statistics and Its Applications, University of Lisbon, Lisbon, Portugal
| | - Kimberly Fornace
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Lynn Grignard
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Julia Mwesigwa
- Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia; Department of Global Health, University of Antwerp, Antwerp, Belgium
| | - Jane Achan
- Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - John Miller
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), National Malaria Elimination Centre, Ministry of Health, Chainama Grounds Lusaka, Zambia
| | - Daniel J Bridges
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), National Malaria Elimination Centre, Ministry of Health, Chainama Grounds Lusaka, Zambia
| | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - Jacklin Mosha
- National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Pauline Joy Lorenzo
- Department of Parasitology, Research Institute for Tropical Medicine, Research Drive, Alabang, Muntinlupa, Metro Manila, Philippines
| | - Maria Lourdes Macalinao
- Department of Parasitology, Research Institute for Tropical Medicine, Research Drive, Alabang, Muntinlupa, Metro Manila, Philippines
| | - Fe Esperanza Espino
- Department of Parasitology, Research Institute for Tropical Medicine, Research Drive, Alabang, Muntinlupa, Metro Manila, Philippines
| | - Fitsum Tadesse
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Jennifer C Stevenson
- Macha Research Trust, Choma District, Zambia; Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | | | - André Siqueira
- Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Manaus, Brazil; Programa de Pós-graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Brazil; Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Marcus Lacerda
- Fundacao de Medicine Tropical Dr. Heitor Viera Dourado, Manaus, Brazil; Institutos Nacionais de Ciencia e Technologia (INCT), Instituto Elimina, Manaus, Brazil
| | - Shunmay Yeung
- Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, UK
| | - Siv Sovannaroth
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Emilie Pothin
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland; Clinton Health Access Initiative, Boston, MA, USA
| | - Joanna Gallay
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Karen E Hamre
- Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, USA; CDC Foundation, Atlanta, GA, USA
| | - Alyssa Young
- Clinton Health Access Initiative, Port-au-Prince, Haiti
| | - Jean Frantz Lemoine
- Programme National de Contrôle de la Malaria, Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | - Michelle A Chang
- Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, USA
| | - Koukeo Phommasone
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Mayfong Mayxay
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Institute of Research and Education Development, University of Health Sciences, Vientiane, Laos
| | - Jordi Landier
- Aix Marseille Univ, IRD, INSERM, SESSTIM, Marseille, France
| | - Daniel M Parker
- Department of Population Health and Disease Prevention and Department of Epidemiology, University of California, Irvine, CA, USA
| | - Lorenz Von Seidlein
- Oxford Tropical Medicine Research Unit, Mahidol University Bangkok, Thailand; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Francois Nosten
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Shoklo Malaria Research Unit, Mae Sot, Thailand
| | - Gilles Delmas
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Shoklo Malaria Research Unit, Mae Sot, Thailand
| | - Arjen Dondorp
- Oxford Tropical Medicine Research Unit, Mahidol University Bangkok, Thailand; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Ewan Cameron
- Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, Australia; Curtin University, Bentley, WA, Australia
| | | | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Peter Gething
- Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA, Australia; Curtin University, Bentley, WA, Australia
| | - Umberto D'Alessandro
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK; Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
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15
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Chua TH, Manin BO, Vythilingam I, Fornace K, Drakeley CJ. Effect of different habitat types on abundance and biting times of Anopheles balabacensis Baisas (Diptera: Culicidae) in Kudat district of Sabah, Malaysia. Parasit Vectors 2019; 12:364. [PMID: 31345256 PMCID: PMC6659233 DOI: 10.1186/s13071-019-3627-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [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: 03/18/2019] [Accepted: 07/19/2019] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND We investigated the effect of five common habitat types on the diversity and abundance of Anopheles spp. and on the biting rate and time of Anopheles balabacensis (currently the only known vector for Plasmodium knowlesi in Sabah) at Paradason village, Kudat, Sabah. The habitats were forest edge, playground area, longhouse, oil palm plantation and shrub-bushes area. Sampling of Anopheles was done monthly using the human landing catch method in all habitat types for 14 months (October 2013 to December 2014, excluding June 2014). The Anopheles species were morphologically identified and subjected to PCR assay for the detection of Plasmodium parasites. Generalised linear mixed models (GLMM) were applied to test the variation in abundance and biting rates of An. balabacensis in different habitat types. RESULTS A total of 1599 Anopheles specimens were collected in the village, of which about 90% were An. balabacensis. Anopheles balabacensis was present throughout the year and was the dominant Anopheles species in all habitat types. The shrub bushes habitat had the highest Anopheles species diversity while forest edge had the greatest number of Anopheles individuals caught. GLMM analysis indicated that An. balabacensis abundance was not affected by the type of habitats, and it was more active during the early and late night compared to predawn and dawn. PCR assay showed that 1.61% of the tested An. balabacensis were positive for malaria parasites, most of which were caught in oil palm estates and infected with one to two Plasmodium species. CONCLUSIONS The identification of infected vectors in a range of habitats, including agricultural and farming areas, illustrates the potential for humans to be exposed to P. knowlesi outside forested areas. This finding contributes to a growing body of evidence implicating environmental changes due to deforestation, expansion of agricultural and farming areas, and development of human settlements near to forest fringes in the emergence of P. knowlesi in Sabah.
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Affiliation(s)
- Tock H Chua
- Department of Pathobiology and Medical Diagnostics, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia.
| | - Benny O Manin
- Department of Pathobiology and Medical Diagnostics, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia
| | - Indra Vythilingam
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Kimberly Fornace
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris J Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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Häsler B, Msalya G, Roesel K, Fornace K, Eltholth M, Sikira A, Kurwijila L, Rushton J, Grace D. Using participatory rural appraisal to investigate food production, nutrition and safety in the Tanzanian dairy value chain. Global Food Security 2019. [DOI: 10.1016/j.gfs.2019.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Häsler B, Msalya G, Garza M, Fornace K, Eltholth M, Kurwijila L, Rushton J, Grace D. Integrated food safety and nutrition assessments in the dairy cattle value chain in Tanzania. Global Food Security 2018. [DOI: 10.1016/j.gfs.2018.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Brown R, Hing CT, Fornace K, Ferguson HM. Evaluation of resting traps to examine the behaviour and ecology of mosquito vectors in an area of rapidly changing land use in Sabah, Malaysian Borneo. Parasit Vectors 2018; 11:346. [PMID: 29898780 PMCID: PMC6000972 DOI: 10.1186/s13071-018-2926-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [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: 03/13/2018] [Accepted: 05/30/2018] [Indexed: 12/22/2022] Open
Abstract
Background Widespread deforestation occurring in the tropics is hypothesized to impact the transmission of vector-borne diseases (VBD). Predicting how environmental changes will impact VBD transmission is dependent on understanding the ecology and behaviour of potential vector species outside of domestic settings. However there are few reliable sampling tools for measuring the habitat preference and host choice of mosquito vectors; with almost none suitable for sampling recently blood-fed, resting mosquitoes. This study evaluated the use of two mosquito traps: the resting bucket (RB) and sticky resting bucket (SRB) traps relative to CDC backpack aspiration (CDC) for sampling mosquitoes resting in a range of habitats representing a gradient of deforestation. Eight habitats were selected for sampling around two villages in Kudat District, Malaysian Borneo, to reflect the range of habitats available to mosquitoes in and around human dwellings, and nearby forest habitats where reservoir hosts are present: secondary forest (edge, interior and canopy); plantations (palm and rubber); and human settlements (inside, under and around houses). Results Over 31 days, 2243 mosquitoes were collected in 5748 discrete collections. Nine mosquito genera were sampled with Aedes and Culex species being present in all habitats and most abundant. RB and CDC backpack aspiration were most efficient for sampling Culex whereas CDC backpack aspiration and SRB were most efficient for Aedes. Most Aedes identified to species level were Ae. albopictus (91%), with their abundance being highest in forest edge habitats. In contrast, Culex were most abundant under houses. Most blood-fed mosquitoes (76%) were found in human settlements; with humans and chickens being the only blood source. Conclusions RB and SRB traps proved capable of sampling mosquitoes resting in all sampled habitats. However, sampling efficiency was generally low (c.0.1 per trap per day), necessitating traps to be deployed in high numbers for mosquito detection. None of the traps were effective for sampling zoonotic malaria vectors; however, SRB collected relatively higher numbers of the dengue vector Ae. albopictus. The higher abundance of mosquitoes in forest edge habitats indicates the potential value of these traps for investigating sylvatic dengue transmission. This study has demonstrated the merits in application of simple resting traps for characterising mosquito vector resting behaviour outside of the home. Electronic supplementary material The online version of this article (10.1186/s13071-018-2926-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rebecca Brown
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Chua Tock Hing
- Department of Pathobiology and Medical Diagnostics, Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, 88400, Kota Kinabalu, Sabah, Malaysia
| | - Kimberly Fornace
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Heather M Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
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19
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Eltholth M, Fornace K, Grace D, Rushton J, Häsler B. Assessing the chemical and microbiological quality of farmed tilapia in Egyptian fresh fish markets. Global Food Security 2018. [DOI: 10.1016/j.gfs.2018.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Herman LS, Fornace K, Phelan J, Grigg MJ, Anstey NM, William T, Moon RW, Blackman MJ, Drakeley CJ, Tetteh KKA. Identification and validation of a novel panel of Plasmodium knowlesi biomarkers of serological exposure. PLoS Negl Trop Dis 2018; 12:e0006457. [PMID: 29902183 PMCID: PMC6001954 DOI: 10.1371/journal.pntd.0006457] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 04/17/2018] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Plasmodium knowlesi is the most common cause of malaria in Malaysian Borneo, with reporting limited to clinical cases presenting to health facilities and scarce data on the true extent of transmission. Serological estimations of transmission have been used with other malaria species to garner information about epidemiological patterns. However, there are a distinct lack of suitable serosurveillance tools for this neglected disease. METHODOLOGY/PRINCIPAL FINDINGS Using in silico tools, we designed and expressed four novel P. knowlesi protein products to address the distinct lack of suitable serosurveillance tools: PkSERA3 antigens 1 and 2, PkSSP2/TRAP and PkTSERA2 antigen 1. Antibody prevalence to these antigens was determined by ELISA for three time-points post-treatment from a hospital-based clinical treatment trial in Sabah, East Malaysia (n = 97 individuals; 241 total samples for all time points). Higher responses were observed for the PkSERA3 antigen 2 (67%, 65/97) across all time-points (day 0: 36.9% 34/92; day 7: 63.8% 46/72; day 28: 58.4% 45/77) with significant differences between the clinical cases and controls (n = 55, mean plus 3 SD) (day 0 p<0.0001; day 7 p<0.0001; day 28 p<0.0001). Using boosted regression trees, we developed models to classify P. knowlesi exposure (cross-validated AUC 88.9%; IQR 86.1-91.3%) and identified the most predictive antibody responses. CONCLUSIONS/SIGNIFICANCE The PkSERA3 antigen 2 had the highest relative variable importance in all models. Further validation of these antigens is underway to determine the specificity of these tools in the context of multi-species infections at the population level.
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Affiliation(s)
- Lou S. Herman
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Kimberly Fornace
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jody Phelan
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Matthew J. Grigg
- Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Nicholas M. Anstey
- Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Timothy William
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
- Clinical Research Centre, Queen Elizabeth Hospital, Kota Kinabalu, Sabah, Malaysia
- Jesselton Medical Centre, Kota Kinabalu, Sabah, Malaysia
| | - Robert W. Moon
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Michael J. Blackman
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Chris J. Drakeley
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Kevin K. A. Tetteh
- Department Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
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21
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Howie SRC, Schellenberg J, Chimah O, Ideh RC, Ebruke BE, Oluwalana C, Mackenzie G, Jallow M, Njie M, Donkor S, Dionisio KL, Goldberg G, Fornace K, Bottomley C, Hill PC, Grant CC, Corrah T, Prentice AM, Ezzati M, Greenwood BM, Smith PG, Adegbola RA, Mulholland K. Childhood pneumonia and crowding, bed-sharing and nutrition: a case-control study from The Gambia. Int J Tuberc Lung Dis 2016; 20:1405-1415. [PMID: 27725055 PMCID: PMC5019143 DOI: 10.5588/ijtld.15.0993] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 05/19/2016] [Indexed: 12/03/2022] Open
Abstract
SETTING Greater Banjul and Upper River Regions, The Gambia. OBJECTIVE To investigate tractable social, environmental and nutritional risk factors for childhood pneumonia. DESIGN A case-control study examining the association of crowding, household air pollution (HAP) and nutritional factors with pneumonia was undertaken in children aged 2-59 months: 458 children with severe pneumonia, defined according to the modified WHO criteria, were compared with 322 children with non-severe pneumonia, and these groups were compared to 801 neighbourhood controls. Controls were matched by age, sex, area and season. RESULTS Strong evidence was found of an association between bed-sharing with someone with a cough and severe pneumonia (adjusted OR [aOR] 5.1, 95%CI 3.2-8.2, P < 0.001) and non-severe pneumonia (aOR 7.3, 95%CI 4.1-13.1, P < 0.001), with 18% of severe cases estimated to be attributable to this risk factor. Malnutrition and pneumonia had clear evidence of association, which was strongest between severe malnutrition and severe pneumonia (aOR 8.7, 95%CI 4.2-17.8, P < 0.001). No association was found between pneumonia and individual carbon monoxide exposure as a measure of HAP. CONCLUSION Bed-sharing with someone with a cough is an important risk factor for severe pneumonia, and potentially tractable to intervention, while malnutrition remains an important tractable determinant.
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Affiliation(s)
- S R C Howie
- Medical Research Council Unit, Fajara, The Gambia; Department of Paediatrics: Child & Youth Health, University of Auckland, Auckland, Centre for International Health, University of Otago, Dunedin, New Zealand
| | - J Schellenberg
- London School of Hygiene & Tropical Medicine, London, UK
| | - O Chimah
- Medical Research Council Unit, Fajara, The Gambia
| | - R C Ideh
- Medical Research Council Unit, Fajara, The Gambia; Child Health Department, University of Benin, Teaching Hospital, Benin City, Nigeria
| | - B E Ebruke
- Medical Research Council Unit, Fajara, The Gambia
| | - C Oluwalana
- Medical Research Council Unit, Fajara, The Gambia
| | - G Mackenzie
- Medical Research Council Unit, Fajara, The Gambia
| | - M Jallow
- Ministry of Health and Social Welfare, Banjul, The Gambia
| | - M Njie
- Ministry of Health and Social Welfare, Banjul, The Gambia
| | - S Donkor
- Medical Research Council Unit, Fajara, The Gambia
| | - K L Dionisio
- Harvard School of Public Health, Department of Global Health and Population, Boston, and Harvard School of Public Health, Department of Environmental Health, Boston, Massachusetts, USA; National Exposure Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - G Goldberg
- MRC-Public Health England Centre for Environment and Health, Imperial College London, London, UK
| | - K Fornace
- Medical Research Council Unit, Fajara, The Gambia, London School of Hygiene & Tropical Medicine, London, UK
| | - C Bottomley
- London School of Hygiene & Tropical Medicine, London, UK
| | - P C Hill
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - C C Grant
- Department of Paediatrics: Child & Youth Health, University of Auckland, Auckland, New Zealand
| | - T Corrah
- Medical Research Council Unit, Fajara, The Gambia
| | - A M Prentice
- Medical Research Council Unit, Fajara, The Gambia, London School of Hygiene & Tropical Medicine, London, UK
| | - M Ezzati
- Medical Research Council (MRC) Human Nutrition Research, Cambridge, UK
| | - B M Greenwood
- London School of Hygiene & Tropical Medicine, London, UK
| | - P G Smith
- London School of Hygiene & Tropical Medicine, London, UK
| | - R A Adegbola
- Medical Research Council Unit, Fajara, The Gambia, GlaxoSmithKline Vaccines, Wavre, Belgium
| | - K Mulholland
- London School of Hygiene & Tropical Medicine, London, UK, Harvard School of Public Health, Department of Global Health and Population, Boston, and Harvard School of Public Health, Department of Environmental Health, Boston, Massachusetts, USA
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Wong ML, Chua TH, Leong CS, Khaw LT, Fornace K, Wan-Sulaiman WY, William T, Drakeley C, Ferguson HM, Vythilingam I. Seasonal and Spatial Dynamics of the Primary Vector of Plasmodium knowlesi within a Major Transmission Focus in Sabah, Malaysia. PLoS Negl Trop Dis 2015; 9:e0004135. [PMID: 26448052 PMCID: PMC4598189 DOI: 10.1371/journal.pntd.0004135] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/10/2015] [Indexed: 11/18/2022] Open
Abstract
Background The simian malaria parasite Plasmodium knowlesi is emerging as a public health problem in Southeast Asia, particularly in Malaysian Borneo where it now accounts for the greatest burden of malaria cases and deaths. Control is hindered by limited understanding of the ecology of potential vector species. Methodology/Principal Findings We conducted a one year longitudinal study of P. knowlesi vectors in three sites within an endemic area of Sabah, Malaysia. All mosquitoes were captured using human landing catch. Anopheles mosquitoes were dissected to determine, oocyst, sporozoites and parous rate. Anopheles balabacensis is confirmed as the primary vector of. P. knowlesi (using nested PCR) in Sabah for the first time. Vector densities were significantly higher and more seasonally variable in the village than forest or small scale farming site. However An. balabacensis survival and P. knowlesi infection rates were highest in forest and small scale farm sites. Anopheles balabacensis mostly bites humans outdoors in the early evening between 1800 to 2000hrs. Conclusions/Significance This study indicates transmission is unlikely to be prevented by bednets. This combined with its high vectorial capacity poses a threat to malaria elimination programmes within the region. The first natural infection of Plasmodium knowlesi was reported 40 years ago. At that time it was perceived that the infection would not affect humans. However, now P. knowlesi is the predominant malaria species (38% of the cases) infecting people in Malaysia and is a notable obstacle to malaria elimination in the country. Plasmodium knowlesi has also been reported from all countries in Southeast Asia with the exception of Lao PDR and Timor Leste. In Sabah, Malaysian Borneo cases of human P. knowlesi are increasing. Thus, a comprehensive understanding of the bionomics of the vectors is required so as to enable proper control strategies. Here, we conducted a longitudinal study in Kudat district, Sabah, to determine and characterize the vectors of P. knowlesi within this transmission foci. Anopheles balabacensis was the predominant mosquito in all study sites and is confirmed as vector for P. knowlesi and other simian malaria parasites. The peak biting time was in the early part of the evening between1800 to 2000. Thus, breaking the chain of transmission is an extremely challenging task for the malaria elimination programme.
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Affiliation(s)
- Meng L. Wong
- Parasitology Department, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Tock H. Chua
- Department of Pathobiology and Medical Diagnostics, Faculty of Medicine and Health Sciences, Universiti Sabah Malaysia, Kota Kinabalu, Sabah, Malaysia
| | - Cherng S. Leong
- Parasitology Department, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Loke T. Khaw
- Parasitology Department, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Kimberly Fornace
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Heather M. Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Scotland, United Kingdom
| | - Indra Vythilingam
- Parasitology Department, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
- * E-mail:
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Zhou Z, Dionisio KL, Verissimo TG, Kerr AS, Coull B, Howie S, Arku RE, Koutrakis P, Spengler JD, Fornace K, Hughes AF, Vallarino J, Agyei-Mensah S, Ezzati M. Chemical characterization and source apportionment of household fine particulate matter in rural, peri-urban, and urban West Africa. Environ Sci Technol 2014; 48:1343-51. [PMID: 24351083 DOI: 10.1021/es404185m] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Household air pollution in sub-Saharan Africa and other developing regions is an important cause of disease burden. Little is known about the chemical composition and sources of household air pollution in sub-Saharan Africa, and how they differ between rural and urban homes. We analyzed the chemical composition and sources of fine particles (PM2.5) in household cooking areas of multiple neighborhoods in Accra, Ghana, and in peri-urban (Banjul) and rural (Basse) areas in The Gambia. In Accra, biomass burning accounted for 39-62% of total PM2.5 mass in the cooking area in different neighborhoods; the absolute contributions were 10-45 μg/m(3). Road dust and vehicle emissions comprised 12-33% of PM2.5 mass. Solid waste burning was also a significant contributor to household PM2.5 in a low-income neighborhood but not for those living in better-off areas. In Banjul and Basse, biomass burning was the single dominant source of cooking-area PM2.5, accounting for 74-87% of its total mass; the relative and absolute contributions of biomass smoke to PM2.5 mass were larger in households that used firewood than in those using charcoal, reaching as high as 463 μg/m(3) in Basse homes that used firewood for cooking. Our findings demonstrate the need for policies that enhance access to cleaner fuels in both rural and urban areas, and for controlling traffic emissions in cities in sub-Saharan Africa.
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Affiliation(s)
- Zheng Zhou
- Department of Global Health and Population, Harvard School of Public Health , Boston, Massachusetts, United States
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