Browsing by Author "Debes AK"

Now showing 1 - 5 of 5

Contrasting Epidemiology of Cholera in Bangladesh and Africa.
(2021-Dec-20) Sack DA; Debes AK; Ateudjieu J; Bwire G; Ali M; Ngwa MC; Mwaba J; Chilengi R; Orach CC; Boru W; Mohamed AA; Ram M; George CM; Stine OC; Ministry of Health and Field Epidemiology and Laboratory Training Program, Nairobi, Kenya.; Tanzania Field Epidemiology and Laboratory Training Program, Dar-es-Salaam, Tanzania.; Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.; Department of Community Health and Behavioural Sciences, Makerere University School of Public Health, Kampala, Uganda.; Department of Epidemiology and Public Health, School of Medicine, University of Maryland, Baltimore, Maryland, USA.; Department of Integrated Epidemiology, Surveillance, and Public Health Emergencies, Ministry of Health, Kampala, Uganda.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; Meilleur Acces aux Soins de Sante, and Department of Public Health, Faculty of Medicine and Pharmaceutical Sciences, University of Dschang, and Clinical Research Unit, Division of Health Operations Research, Cameroon Ministry of Public Health, Yaoundé, Cameroon.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
In Bangladesh and West Bengal cholera is seasonal, transmission occurs consistently annually. By contrast, in most African countries, cholera has inconsistent seasonal patterns and long periods without obvious transmission. Transmission patterns in Africa occur during intermittent outbreaks followed by elimination of that genetic lineage. Later another outbreak may occur because of reintroduction of new or evolved lineages from adjacent areas, often by human travelers. These then subsequently undergo subsequent elimination. The frequent elimination and reintroduction has several implications when planning for cholera's elimination including: a) reconsidering concepts of definition of elimination, b) stress on rapid detection and response to outbreaks, c) more effective use of oral cholera vaccine and WASH, d) need to readjust estimates of disease burden for Africa, e) re-examination of water as a reservoir for maintaining endemicity in Africa. This paper reviews major features of cholera's epidemiology in African countries which appear different from the Ganges Delta.
Identification of cholera hotspots in Zambia: A spatiotemporal analysis of cholera data from 2008 to 2017.
(2020-Apr) Mwaba J; Debes AK; Shea P; Mukonka V; Chewe O; Chisenga C; Simuyandi M; Kwenda G; Sack D; Chilengi R; Ali M; Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; Zambia National Public Health Institute, Lusaka, Zambia.; University of Zambia, School of Health Sciences, Lusaka, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
The global burden of cholera is increasing, with the majority (60%) of the cases occurring in sub-Saharan Africa. In Zambia, widespread cholera outbreaks have occurred since 1977, predominantly in the capital city of Lusaka. During both the 2016 and 2018 outbreaks, the Ministry of Health implemented cholera vaccination in addition to other preventative and control measures, to stop the spread and control the outbreak. Given the limitations in vaccine availability and the logistical support required for vaccination, oral cholera vaccine (OCV) is now recommended for use in the high risk areas ("hotspots") for cholera. Hence, the aim of this study was to identify areas with an increased risk of cholera in Zambia. Retrospective cholera case data from 2008 to 2017 was obtained from the Ministry of Health, Department of Public Health and Disease Surveillance. The Zambian Central Statistical Office provided district-level population data, socioeconomic and water, sanitation and hygiene (WaSH) indicators. To identify districts at high risk, we performed a discrete Poisson-based space-time scan statistic to account for variations in cholera risk across both space and time over a 10-year study period. A zero-inflated negative binomial regression model was employed to identify the district level risk factors for cholera. The risk map was generated by classifying the relative risk of cholera in each district, as obtained from the space-scan test statistic. In total, 34,950 cases of cholera were reported in Zambia between 2008 and 2017. Cholera cases varied spatially by year. During the study period, Lusaka District had the highest burden of cholera, with 29,080 reported cases. The space-time scan statistic identified 16 districts to be at a significantly higher risk of having cholera. The relative risk of having cholera in these districts was significantly higher and ranged from 1.25 to 78.87 times higher when compared to elsewhere in the country. Proximity to waterbodies was the only factor associated with the increased risk for cholera (P<0.05). This study provides a basis for the cholera elimination program in Zambia. Outside Lusaka, the majority of high risk districts identified were near the border with the DRC, Tanzania, Mozambique, and Zimbabwe. This suggests that cholera in Zambia may be linked to movement of people from neighboring areas of cholera endemicity. A collaborative intervention program implemented in concert with neighboring countries could be an effective strategy for elimination of cholera in Zambia, while also reducing rates at a regional level.
Serum vibriocidal responses when second doses of oral cholera vaccine are delayed 6 months in Zambia.
(2021-Jul-22) Mwaba J; Chisenga CC; Xiao S; Ng'ombe H; Banda E; Shea P; Mabula-Bwalya C; Mwila-Kazimbaya K; Laban NM; Alabi P; Chirwa-Chobe M; Simuyandi M; Harris J; Iyer AS; Bosomprah S; Scalzo P; Murt KN; Ram M; Kwenda G; Ali M; Sack DA; Chilengi R; Debes AK; Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA.; Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. Electronic address: adebes1@jhu.edu.; Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.; Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA; Department of Pediatrics, Harvard Medical School, Boston, MA, USA.; Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia.; Research Department, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; Research Department, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia; Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia.; Research Department, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia; London School of Hygiene and Tropical Medicine, United Kingdom.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
Two-dose killed oral cholera vaccines (OCV) are currently being used widely to control cholera. The standard dose-interval for OCV is 2 weeks; however, during emergency use of the vaccine, it may be more appropriate to use the available doses to quickly give a single dose to more people and give a delayed second dose when more vaccine becomes available. This study is an open label, randomized, phase 2 clinical trial of the vibriocidal response induced by OCV, comparing the responses when the second dose was given either 2 weeks (standard dose interval) or 6 months (extended dose interval) after the first dose. Vaccine was administered to healthy participants > 1 year of age living in the Lukanga Swamps area of Zambia. Three age cohorts (<5 years, 5-14 years, and ≥ 15 years) were randomized to the either dose-interval. The primary outcome was the vibriocidal GMT 14 days after the second dose. 156 of 172 subjects enrolled in the study were included in this analysis. The Inaba vibriocidal titers were not significantly different 14 days post dose two for a standard dose-interval GMT: 45.6 (32-64.9), as compared to the GMT 47.6 (32.6-69.3), for the extended dose-interval, (p = 0.87). However, the Ogawa vibriocidal GMTs were significantly higher 14 days post dose two for the extended-dose interval at 87.6 (58.9-130.4) compared to the standard dose-interval group at 49.7 (34.1-72.3), p = 0.04. Vibriocidal seroconversion rates (a > 4-fold rise in vibriocidal titer) were not significantly different between dose-interval groups. This study demonstrated that vibriocidal titers 14 days after a second dose when given at an extended\ dose interval were similar to the standard dose-interval. The findings suggest that a flexible dosing schedule may be considered when epidemiologically appropriate. The trial was registered at Clinical Trials.gov (NCT03373669).
Spatiotemporal variation in risk of Shigella infection in childhood: a global risk mapping and prediction model using individual participant data.
(2023-Mar) Badr HS; Colston JM; Nguyen NH; Chen YT; Burnett E; Ali SA; Rayamajhi A; Satter SM; Van Trang N; Eibach D; Krumkamp R; May J; Adegnika AA; Manouana GP; Kremsner PG; Chilengi R; Hatyoka L; Debes AK; Ateudjieu J; Faruque ASG; Hossain MJ; Kanungo S; Kotloff KL; Mandomando I; Nisar MI; Omore R; Sow SO; Zaidi AKM; Lambrecht N; Adu B; Page N; Platts-Mills JA; Mavacala Freitas C; Pelkonen T; Ashorn P; Maleta K; Ahmed T; Bessong P; Bhutta ZA; Mason C; Mduma E; Olortegui MP; Peñataro Yori P; Lima AAM; Kang G; Humphrey J; Ntozini R; Prendergast AJ; Okada K; Wongboot W; Langeland N; Moyo SJ; Gaensbauer J; Melgar M; Freeman M; Chard AN; Thongpaseuth V; Houpt E; Zaitchik BF; Kosek MN; College of Medicine, University of Malawi, Blantyre, Malawi.; Centro de Investigação em Saúde de Manhiça, Manhica, Mozambique.; National Institute of Cholera and Enteric Diseases, Kolkota, India.; Asociacion Benefica PRISMA, Iquitos, Peru.; Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand.; Department of Earth and Planetary Sciences, Johns Hopkins Krieger School of Arts and Sciences, Baltimore, MA, USA.; New Children's Hospital, Pediatric Research Center and Helsinki University Hospital, Helsinki, Finland.; Faculty of Medicine and Pharmaceutical Sciences, University of Dschang, Dschang, Cameroon; Department of Health Research, M A SANTE (Meileur Acces aux Soins en Santé), Yaoundé, Cameroon; Division of Health Operations Research, Cameroon Ministry of Public Health, Yaoundé, Cameroon.; Enteric diseases and Vaccines Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine (BNITM), Hamburg, Germany.; Center of Excellence in Women and Child Health, Aga Khan University, Karachi, Pakistan.; Department of Clinical Science, University of Bergen, Bergen, Norway.; Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana.; Department of Gastrointestinal Sciences, Christian Medical College, Vellore, India.; Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, VA, USA.; College of Arts and Sciences, University of Virginia, VI, USA.; Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, 30322, GA, USA.; Laboratory and Treatment Unit, Center for Malariology, Parasitology, and Entomology, Ministry of Health, Vientiane, Lao PDR.; Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia.; Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand.; Center for Global Health, Department of Epidemiology, Colorado School of Public Health, Aurora, CO, USA.; Programme for Emerging Infections, Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.; Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.; Centre for Enteric Diseases, National Institute for Communicable Diseases, Pretoria, South Africa.; Hospital Pediátrico David Bernardino, Luanda, Angola.; Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.; Blizard Institute, Queen Mary University of London, London, UK.; Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.; Institute of Tropical Medicine, Universitätsklinikum Tübingen, Tübingen, Germany.; Pediatric Infectious Diseases, Hospital Roosevelt, Guatemala City, Guatemala.; Centre for Child, Adolescent, and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University and Tampere University Hospital, Tampere, Finland.; Division of Viral Diseases, US Centers for Disease Control and Prevention, Atlanta, GA, USA.; Centre pour le Développement des Vaccins, Mali, Bamako, Mali.; Department of Emergency Medicine, Chi-Mei Medical Center, Tainan, Taiwan.; Centre for Nutrition & Food Security, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.; Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, USA.; Department of Earth and Planetary Sciences, Johns Hopkins Krieger School of Arts and Sciences, Baltimore, MA, USA. Electronic address: zaitchik@jhu.edu.; Kenya Medical Research Institute, Center for Global Health Research, Kisumu, Nyanza, Kenya.; Department of Pediatrics, National Academy of Medical Sciences, Kanti Children's Hospital, Kathmandu, Nepal.; National Institute of Hygiene and Epidemiology, Ha Noi, Vietnam.; Institute of Public Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany; Research Department 2, Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, Potsdam, Germany.; Haydom Global Health Institute, Haydom, Tanzania.; Department of Physiology and Pharmacology, Faculty of Medicine, Federal University of Ceará, Fortaleza, Brazil.; Department of Pediatrics and Child Health, Aga Khan University, Karachi, Pakistan.; Zvitambo Institute for Maternal and Child Health Research, Harare, Zimbabwe.; HIV/AIDS & Global Health Research Programme, University of Venda, Thohoyandou, Limpopo, South Africa.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
BACKGROUND: Diarrhoeal disease is a leading cause of childhood illness and death globally, and Shigella is a major aetiological contributor for which a vaccine might soon be available. The primary objective of this study was to model the spatiotemporal variation in paediatric Shigella infection and map its predicted prevalence across low-income and middle-income countries (LMICs). METHODS: Individual participant data for Shigella positivity in stool samples were sourced from multiple LMIC-based studies of children aged 59 months or younger. Covariates included household-level and participant-level factors ascertained by study investigators and environmental and hydrometeorological variables extracted from various data products at georeferenced child locations. Multivariate models were fitted and prevalence predictions obtained by syndrome and age stratum. FINDINGS: 20 studies from 23 countries (including locations in Central America and South America, sub-Saharan Africa, and south and southeast Asia) contributed 66 563 sample results. Age, symptom status, and study design contributed most to model performance followed by temperature, wind speed, relative humidity, and soil moisture. Probability of Shigella infection exceeded 20% when both precipitation and soil moisture were above average and had a 43% peak in uncomplicated diarrhoea cases at 33°C temperatures, above which it decreased. Compared with unimproved sanitation, improved sanitation decreased the odds of Shigella infection by 19% (odds ratio [OR]=0·81 [95% CI 0·76-0·86]) and open defecation decreased them by 18% (OR=0·82 [0·76-0·88]). INTERPRETATION: The distribution of Shigella is more sensitive to climatological factors, such as temperature, than previously recognised. Conditions in much of sub-Saharan Africa are particularly propitious for Shigella transmission, although hotspots also occur in South America and Central America, the Ganges-Brahmaputra Delta, and the island of New Guinea. These findings can inform prioritisation of populations for future vaccine trials and campaigns. FUNDING: NASA, National Institutes of Health-The National Institute of Allergy and Infectious Diseases, and Bill & Melinda Gates Foundation.
Three transmission events of Vibrio cholerae O1 into Lusaka, Zambia.
(2021-Jun-14) Mwaba J; Debes AK; Murt KN; Shea P; Simuyandi M; Laban N; Kazimbaya K; Chisenga C; Li S; Almeida M; Meisel JS; Shibemba A; Kantenga T; Mukonka V; Kwenda G; Sack DA; Chilengi R; Stine OC; Johns Hopkins Bloomberg School of Public Health, MD, Baltimore, USA.; Zambia National Public Health Institute, Lusaka, Zambia.; Department of Biomedical Sciences, University of Zambia School of Health Sciences, Lusaka, Zambia.; Department of Pathology and Microbiology, University Teaching Hospitals, Lusaka, Zambia.; University of Maryland School of Medicine, Baltimore, MD, USA.; University of Maryland, College Park, College Park, MD, USA.; University of Maryland School of Medicine, Baltimore, MD, USA. cstine@som.umaryland.edu.; Université Paris-Saclay, INRAE, MGP, 78350, Jouy-en-Josas, France.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
BACKGROUND: Cholera has been present and recurring in Zambia since 1977. However, there is a paucity of data on genetic relatedness and diversity of the Vibrio cholerae isolates responsible for these outbreaks. Understanding whether the outbreaks are seeded from existing local isolates or if the outbreaks represent separate transmission events can inform public health decisions. RESULTS: Seventy-two V. cholerae isolates from outbreaks in 2009/2010, 2016, and 2017/2018 in Zambia were characterized using multilocus variable number tandem repeat analysis (MLVA) and whole genome sequencing (WGS). The isolates had eight distinct MLVA genotypes that clustered into three MLVA clonal complexes (CCs). Each CC contained isolates from only one outbreak. The results from WGS revealed both clustered and dispersed single nucleotide variants. The genetic relatedness of isolates based on WGS was consistent with the MLVA, each CC was a distinct genetic lineage and had nearest neighbors from other East African countries. In Lusaka, isolates from the same outbreak were more closely related to themselves and isolates from other countries than to isolates from other outbreaks in other years. CONCLUSIONS: Our observations are consistent with i) the presence of random mutation and alternative mechanisms of nucleotide variation, and ii) three separate transmission events of V. cholerae into Lusaka, Zambia. We suggest that locally, case-area targeted invention strategies and regionally, well-coordinated plans be in place to effectively control future cholera outbreaks.