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Tadesse BT, Khanam F, Ahmmed F, Liu X, Islam MT, Kim DR, Kang SS, Im J, Chowdhury F, Ahmed T, Aziz AB, Hoque M, Park J, Pak G, Jeon HJ, Zaman K, Khan AI, Kim JH, Marks F, Qadri F, Clemens JD. Association Among Household Water, Sanitation, and Hygiene (WASH) Status and Typhoid Risk in Urban Slums: Prospective Cohort Study in Bangladesh. JMIR Public Health Surveill 2023; 9:e41207. [PMID: 37983081 PMCID: PMC10696503 DOI: 10.2196/41207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/30/2023] [Accepted: 10/05/2023] [Indexed: 11/21/2023] Open
Abstract
BACKGROUND Typhoid fever, or enteric fever, is a highly fatal infectious disease that affects over 9 million people worldwide each year, resulting in more than 110,000 deaths. Reduction in the burden of typhoid in low-income countries is crucial for public health and requires the implementation of feasible water, sanitation, and hygiene (WASH) interventions, especially in densely populated urban slums. OBJECTIVE In this study, conducted in Mirpur, Bangladesh, we aimed to assess the association between household WASH status and typhoid risk in a training subpopulation of a large prospective cohort (n=98,087), and to evaluate the performance of a machine learning algorithm in creating a composite WASH variable. Further, we investigated the protection associated with living in households with improved WASH facilities and in clusters with increasing prevalence of such facilities during a 2-year follow-up period. METHODS We used a machine learning algorithm to create a dichotomous composite variable ("Better" and "Not Better") based on 3 WASH variables: private toilet facility, safe drinking water source, and presence of water filter. The algorithm was trained using data from the training subpopulation and then validated in a distinct subpopulation (n=65,286) to assess its sensitivity and specificity. Cox regression models were used to evaluate the protective effect of living in "Better" WASH households and in clusters with increasing levels of "Better" WASH prevalence. RESULTS We found that residence in households with improved WASH facilities was associated with a 38% reduction in typhoid risk (adjusted hazard ratio=0.62, 95% CI 0.49-0.78; P<.001). This reduction was particularly pronounced in individuals younger than 10 years at the first census participation, with an adjusted hazard ratio of 0.49 (95% CI 0.36-0.66; P<.001). Furthermore, we observed an inverse relationship between the prevalence of "Better" WASH facilities in clusters and the incidence of typhoid, although this association was not statistically significant in the multivariable model. Specifically, the adjusted hazard of typhoid decreased by 0.996 (95% CI 0.986-1.006) for each percent increase in the prevalence of "Better" WASH in the cluster (P=.39). CONCLUSIONS Our findings demonstrate that existing variations in household WASH are associated with differences in the risk of typhoid in densely populated urban slums. This suggests that attainable improvements in WASH facilities can contribute to enhanced typhoid control, especially in settings where major infrastructural improvements are challenging. These findings underscore the importance of implementing and promoting comprehensive WASH interventions in low-income countries as a means to reduce the burden of typhoid and improve public health outcomes in vulnerable populations.
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Affiliation(s)
- Birkneh Tilahun Tadesse
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Farhana Khanam
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Faisal Ahmmed
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Xinxue Liu
- Oxford Vaccine Group, Department of Pediatrics, University of Oxford, Oxford, United Kingdom
| | - Md Taufiqul Islam
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Deok Ryun Kim
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Sophie Sy Kang
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Justin Im
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Fahima Chowdhury
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Tasnuva Ahmed
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Asma Binte Aziz
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Masuma Hoque
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Juyeon Park
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Gideok Pak
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Hyon Jin Jeon
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Khalequ Zaman
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Ashraful Islam Khan
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Jerome H Kim
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Florian Marks
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
- Madagascar Institute for Vaccine Research, University of Antananarivo, Antananarivo, Madagascar
| | - Firdausi Qadri
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - John D Clemens
- Epidemiology, Public Health, Impact Unit, International Vaccine Institute, Seoul, Republic of Korea
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
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