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Oluoch GO, Otundo D, Nyawacha S, Ongeri D, Smith M, Meta V, Trelfa A, Ahmed S, Harrison RA, Lalloo DG, Stienstra Y, Tianyi FL. Conducting epidemiological studies on snakebite in nomadic populations: A methodological paper. PLoS Negl Trop Dis 2023; 17:e0011792. [PMID: 38153942 PMCID: PMC10754435 DOI: 10.1371/journal.pntd.0011792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 11/13/2023] [Indexed: 12/30/2023] Open
Abstract
INTRODUCTION Research on snakebite has mostly been conducted on settled populations and current risk factors and potential interventions are therefore most suited for these populations. There is limited epidemiological data on mobile and nomadic populations, who may have a higher risk of snakebite. METHODS AND RESULTS We conducted a scoping review to gather evidence on survey methods used in nomadic populations and compared them with contemporary survey methods used for snakebite research. Only 16 (10.5%) of 154 articles reportedly conducted on pastoralist nomadic populations actually involved mobile pastoralists. All articles describing snakebite surveys (n = 18) used multistage cluster designs on population census sampling frames, which would not be appropriate for nomadic populations. We used geospatial techniques and open-source high-resolution satellite images to create a digital sampling frame of 50,707 households and used a multistage sampling strategy to survey nomadic and semi-nomadic populations in Samburu County, Kenya. From a sample of 900 geo-located households, we correctly identified and collected data from 573 (65.4%) households, of which 409 were in their original locations and 164 had moved within 5km of their original locations. We randomly sampled 302 (34.6%) households to replace completely abandoned and untraceable households. CONCLUSION Highly mobile populations require specific considerations in selecting or creating sampling frames and sampling units for epidemiological research. Snakebite risk has a strong spatial component and using census-based sampling frames would be inappropriate in nomadic populations. We propose using open-source satellite imaging and geographic information systems to improve the conduct of epidemiological research in these populations.
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Affiliation(s)
- George O. Oluoch
- Kenya Snakebite Research and Intervention Centre, Kenya Institute of Primate Research, Ministry of Health, Karen, Nairobi, Kenya
- Centre for Snakebite Research and Interventions, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Pembroke Place, Liverpool, United Kingdom
| | - Denis Otundo
- Kenya Snakebite Research and Intervention Centre, Kenya Institute of Primate Research, Ministry of Health, Karen, Nairobi, Kenya
| | | | | | | | | | - Anna Trelfa
- Centre for Snakebite Research and Interventions, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Pembroke Place, Liverpool, United Kingdom
| | - Sayem Ahmed
- Centre for Snakebite Research and Interventions, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Pembroke Place, Liverpool, United Kingdom
- Health Economics and Health Technology Assessment, School of Health and Wellbeing, University of Glasgow, Glasgow, United Kingdom
| | - Robert A. Harrison
- Kenya Snakebite Research and Intervention Centre, Kenya Institute of Primate Research, Ministry of Health, Karen, Nairobi, Kenya
- Centre for Snakebite Research and Interventions, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Pembroke Place, Liverpool, United Kingdom
| | - David G. Lalloo
- Centre for Snakebite Research and Interventions, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Pembroke Place, Liverpool, United Kingdom
| | - Ymkje Stienstra
- Centre for Snakebite Research and Interventions, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Pembroke Place, Liverpool, United Kingdom
- University of Groningen, University Medical Centre Groningen, Department of Internal Medicine/Infectious Diseases, Groningen, The Netherlands
| | - Frank-Leonel Tianyi
- Centre for Snakebite Research and Interventions, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Pembroke Place, Liverpool, United Kingdom
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Hazel A, Meeks G, Bharti N, Jakurama J, Matundu J, Jones JH. Opportunities and constraints in women's resource security amid climate change: A case study of arid-living Namibian agro-pastoralists. Am J Hum Biol 2021; 33:e23633. [PMID: 34181282 DOI: 10.1002/ajhb.23633] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE We describe the composition and variation of women's resource strategies in an arid-living Southern African agro-pastoralist society to gain insights into adaptation to climate-change-induced increased aridity. METHODS Using cross-sectional data from 210 women collected in 2009 across 28 agro-pastoralist villages in Kaokoveld Namibia, we conducted principal-component (PC) analysis of resource variables and constructed profiles of resource strategies from the major PCs. Next, we explored associations between key resource strategies and demographic measures and fitness proxies. RESULTS The first two PCs accounted for 43% of women's overall resource variation. PC1 reflects women's ability to access market resources via livestock trading, while PC2 captured women's direct food access. We found that market strategies were more common among married women and less common among women who have experienced child mortality. Women with higher subsistence security were more likely to be from the OvaHimba tribe and had a higher risk of gonorrhea exposure. We also qualitatively explored drought-induced pressure on women's livestock. Finally, we show that sexual networks were attenuated during drought, indicating strain on social support. CONCLUSIONS Our results highlight how agro-pastoralist women manage critical resources in unpredictable environments, and how resource strategies distribute among the women in our study. Goats as a commodity to obtain critical resources suggests that some women have flexibility during drought when gardens fail and cattle die. However, increased aridity and drought may eventually overwhelm husbandry practices in this region.
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Affiliation(s)
- Ashley Hazel
- Department of Earth System Science, Woods Institute for the Environment, Stanford University, Stanford, California, USA
| | - Gillian Meeks
- Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA.,Program in Integrative Genetics and Genomics, University of California, Davis, Davis, California, USA
| | - Nita Bharti
- Department of Biology, The Center for Infectious Disease Dynamics, The Pennsylvania State University, State College, Pennsylvania, USA
| | | | | | - James Holland Jones
- Department of Earth System Science, Woods Institute for the Environment, Stanford University, Stanford, California, USA
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James C, Harfouche M, Welton NJ, Turner KM, Abu-Raddad LJ, Gottlieb SL, Looker KJ. Herpes simplex virus: global infection prevalence and incidence estimates, 2016. Bull World Health Organ 2020; 98:315-329. [PMID: 32514197 PMCID: PMC7265941 DOI: 10.2471/blt.19.237149] [Citation(s) in RCA: 310] [Impact Index Per Article: 77.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 01/21/2020] [Accepted: 01/21/2020] [Indexed: 12/25/2022] Open
Abstract
Objective To generate global and regional estimates for the prevalence and incidence of herpes simplex virus (HSV) type 1 and type 2 infection for 2016. Methods To obtain data, we undertook a systematic review to identify studies up to August 2018. Adjustments were made to account for HSV test sensitivity and specificity. For each World Health Organization (WHO) region, we applied a constant incidence model to pooled prevalence by age and sex to estimate the prevalence and incidence of HSV types 1 and 2 infections. For HSV type 1, we apportioned infection by anatomical site using pooled estimates of the proportions that were oral and genital. Findings In 2016, an estimated 491.5 million people (95% uncertainty interval, UI: 430.4 million–610.6 million) were living with HSV type 2 infection, equivalent to 13.2% of the world’s population aged 15–49 years. An estimated 3752.0 million people (95% UI: 3555.5 million–3854.6 million) had HSV type 1 infection at any site, equivalent to a global prevalence of 66.6% in 0–49-year-olds. Differing patterns were observed by age, sex and geographical region, with HSV type 2 prevalence being highest among women and in the WHO African Region. Conclusion An estimated half a billion people had genital infection with HSV type 2 or type 1, and several billion had oral HSV type 1 infection. Millions of people may also be at higher risk of acquiring human immunodeficiency virus (HIV), particularly women in the WHO African Region who have the highest HSV type 2 prevalence and exposure to HIV.
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Affiliation(s)
- Charlotte James
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, England
| | | | - Nicky J Welton
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, England
| | | | | | - Sami L Gottlieb
- Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland
| | - Katharine J Looker
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, Oakfield House, Oakfield Grove, Bristol BS8 2BN, England
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Mackinnon E, Ayah R, Taylor R, Owor M, Ssempebwa J, Olago LD, Kubalako R, Dia AT, Gaye C, C Campos L, Fottrell E. 21st century research in urban WASH and health in sub-Saharan Africa: methods and outcomes in transition. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2019; 29:457-478. [PMID: 30545246 DOI: 10.1080/09603123.2018.1550193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 11/15/2018] [Indexed: 06/09/2023]
Abstract
Tackling global inequalities in access to Water, Sanitation and Hygiene (WASH) remains an urgent issue - 58% of annual diarrhoeal deaths are caused by inadequate WASH provision. A global context of increasing urbanisation, changing demographics and health transitions demands an understanding and impact of WASH on a broad set of health outcomes. We examine the literature, in terms of health outcomes, considering WASH access and interventions in urban sub-Saharan Africa from 2000 to 2017. Our review of studies which evaluate the effectiveness of specific WASH interventions, reveals an emphasis of WASH research on acute communicable diseases, particularly diarrhoeal diseases. In contrast, chronic communicable and non-communicable health outcomes were notable gaps in the literature as well as a lack of focus on cross-cutting issues, such as ageing, well-being and gender equality. We recommend a broader focus of WASH research and interventions in urban Africa to better reflect the demographic and health transitions happening. Abbreviations: CBA: Controlled Before and After; GSD: Government Service Delivery; IWDSSD: International Drinking-Water, Supply and Sanitation Decade (IDWSSD); KAP: Knowledge, Attitudes and Practices; IBD: Irritable Bowel Diseases; MDG: Millennium Development Goals; NTD: Neglected Tropical Diseases; PSSD: Private Sector Service Delivery; SDG: Sustainable Development Goals; SSA: Sub Saharan Africa; SODIS: Solar Disinfection System; STH: Soil Transmitted Helminths; RCT: Randomised Control Trial; WASH: Water Sanitation and Hygiene; WHO: World Health Organization.
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Affiliation(s)
- Eve Mackinnon
- a Civil, Environmental and Geomatic Engineering , University College London , London , United Kingdom of Great Britain and Northern Ireland
| | - Richard Ayah
- b Faculty of Science Engineering and Health , Daystar University Nairobi , Nairobi , Kenya
| | - Richard Taylor
- c Department of Geography , University College London , London , United Kingdom of Great Britain and Northern Ireland
| | - Michael Owor
- d Department of Geology and Petroleum Studies , Makerere University , Kampala , Uganda
| | - John Ssempebwa
- e College of Agricultural and Environmental Sciences , Makerere University , Kampala , Uganda
| | - L Daniel Olago
- b Faculty of Science Engineering and Health , Daystar University Nairobi , Nairobi , Kenya
| | - Robinah Kubalako
- e College of Agricultural and Environmental Sciences , Makerere University , Kampala , Uganda
| | - Anta Tal Dia
- f Department of Geology, FST , Universite Cheikh Anta Diop , Dakar , Senegal
| | - Cheikh Gaye
- f Department of Geology, FST , Universite Cheikh Anta Diop , Dakar , Senegal
| | - Luiza C Campos
- a Civil, Environmental and Geomatic Engineering , University College London , London , United Kingdom of Great Britain and Northern Ireland
| | - Edward Fottrell
- g University College, London Institute of Global Health , London , United Kingdom of Great Britain and Northern Ireland
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Hazel A, Holland Jones J. Remoteness influences access to sexual partners and drives patterns of viral sexually transmitted infection prevalence among nomadic pastoralists. PLoS One 2018; 13:e0191168. [PMID: 29385170 PMCID: PMC5791958 DOI: 10.1371/journal.pone.0191168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 12/05/2017] [Indexed: 01/01/2023] Open
Abstract
Sexually transmitted infections (STIs) comprise a significant portion of the infectious-disease burden among rural people in the Global South. Particular characteristics of ruralness-low-density settlements and poor infrastructure-make healthcare provision difficult, and remoteness, typically a characteristic of ruralness, often compounds the difficultly. Remoteness may also accelerate STI transmission, particularly that of viral STIs, through formation of small, highly connected sexual networks through which pathogens can spread rapidly, especially when partner concurrency is broadly accepted. Herein, we explored the effect of remoteness on herpes simplex virus type-2 (HSV-2) epidemiology among semi-nomadic pastoralists in northwestern (Kaokoveld) Namibia, where, in 2009 we collected HSV-2-specific antibody status, demographic, sexual network, and travel data from 446 subjects (women = 213, men = 233) in a cross-sectional study design. HSV-2 prevalence was high overall in Kaokoveld (>35%), but was heterogeneously distributed across locally defined residential regions: some regions had significantly higher HSV-2 prevalence (39-48%) than others (21-33%). Using log-linear models, we asked the following questions: 1) Are sexual contacts among people in high HSV-2-prevalence regions more likely to be homophilous (i.e., from the same region) than those among people from low-prevalence regions? 2) Are high-prevalence regions more "functionally" remote, in that people from those regions are more likely to travel within their own region than outside, compared to people from other regions? We found that high-prevalence regions were more sexually homophilous than low-prevalence regions and that those regions also had higher rates of within-region travel than the other regions. These findings indicate that remoteness can create contact structures for accelerated STI transmission among people who are already disproportionately vulnerable to consequences of untreated STIs.
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Affiliation(s)
- Ashley Hazel
- Department of Earth System Science, Stanford University, Stanford, California, United States of America
- Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
- * E-mail:
| | - James Holland Jones
- Department of Earth System Science, Stanford University, Stanford, California, United States of America
- Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
- Division of Biological Sciences, Imperial College London, London, United Kingdom
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