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We evaluated the spatiotemporal clustering of rapid diagnostic test−positive cholera cases in Uvira, eastern Democratic Republic of the Congo. We detected spatiotemporal clusters that consistently overlapped with major rivers, and we outlined the extent of zones of increased risk that are compatible with the radii currently used for targeted interventions.

BackgroundSafely managed drinking water is critical to prevent diarrhoeal diseases, including cholera, but evidence on the effectiveness of piped water supply in reducing these diseases in low-income and complex emergency settings remains scarce.MethodsWe conducted a trial of water supply infrastructure improvements in Uvira (DRC). Our primary objective was to estimate the relationship between a composite index of water service quality and the monthly number of suspected cholera cases admitted to treatment facilities and, as a secondary analysis, the number of cases confirmed by rapid diagnostic tests. Other exposures included the quantity of supplied water and service continuity. We used Poisson generalised linear models with generalised estimating equations to estimate incidence rate ratios.FindingsAssociations between suspected cholera incidence and water service quality (RR 0·86, 95% CI 0·73-1·01), quantity (RR 0·80, 95% CI 0·62-1·02) and continuity (RR 0·81, 95% CI 0·77-0·86) were estimated. The magnitudes of the associations were similar between confirmed cholera incidence and water service quality (RR 0·84, 95% CI 0·73-0·97), quantity (RR 0·76, 95% CI 0·61-0·94) and continuity (RR 0·75, 95% CI 0·69-0·81). These results suggest that an additional 5 L/user/day or 1.2 hour per day of water production could reduce confirmed cholera by 24% (95% CI 6-39%) and 25% (95% CI 19-31%), respectively.InterpretationEnsuring a sufficient and continuous piped water supply may substantially reduce the burden of endemic cholera and diarrhoeal diseases but evaluating this rigorously is challenging. Pragmatic strategies are needed for public health research on complex interventions in protracted emergency settings.Trial registrationThe trial is registered in ClinicalTrials.gov ID NCT02928341. https://classic.clinicaltrials.gov/ct2/show/NCT02928341.

Africa’s Lake Tanganyika basin is a cholera hotspot. During 2001–2020, Vibrio cholerae O1 isolates obtained from the Democratic Republic of the Congo side of the lake belonged to 2 of the 5 clades of the AFR10 sublineage. One clade became predominant after acquiring a parC mutation that decreased susceptibility to ciprofloxacin.

Resume (version française) Please note this translation has been generated by the authors and has not been checked against the original, peer-reviewed English version by the Journal. Any discrepancies between the two versions should be raised with the authors. Cette traduction a été préparée par les auteurs et sa conformité avec la version anglaise revue par les pairs n’a pas été vérifiée par le journal. Toute différence entre les deux versions doit être signalée aux auteurs. Introduction Les maladies diarrhéiques restent une cause majeure de mortalité et morbidité dans le monde. Le choléra seul cause environ 95’000 morts par an, dont la plupart dans des contextes endémiques où l’accès à l’eau est inadéquat. Tandis qu’une stratégie globale pour l’élimination du choléra d’ici à 2030 appelle des investissements dans l’amélioration des services d’approvisionnement en eau, il y a peu de données probantes et rigoureuses sur l’impact d’un approvisionnement en eau amélioré sur la transmission endémique du choléra dans les contextes urbains à faibles ressources. Notre protocole d’étude est conçu pour livrer une évaluation d’impact épidémiologique pragmatique d’une intervention d’approvisionnement en eau à large échelle à Uvira, République Démocratique du Congo, un point focal de transmission du choléra. Méthodes/Conception Un essai randomisé par grappes par échelons (stepped-wedge cluster randomised trial, SW-CRT) a été conçu pour évaluer l’impact d’une intervention d’approvisionnement en eau potable à large échelle sur l’incidence du choléra parmi les 280'000 habitants d’Uvira. La ville a été divisée en 16 grappes, dans lesquelles de nouvelles bornes fontaines et branchements individuels seront installés suivant une séquence randomisée sur une période allant jusqu’à 8 semaines par grappe. Le principal résultat de l’essai sera l’incidence mensuelle des cas de choléra « confirmés » (patients positifs par tests de détection rapide) et des cas « suspects » (patients admis au centre de traitement du choléra). Des évaluations de processus et économique menées en parallèle fourniront des informations complémentaires sur le contexte, les coûts et l’efficience de l’intervention. Discussion Dans ce protocole, nous présentons une approche pragmatique pour effectuer une recherche rigoureuse visant à évaluer les impacts d’une intervention complexe d’approvisionnement en eau sur la diarrhée sévère et le choléra dans un contexte instable et à faibles ressources, représentatif des zones affectées par le choléra. En particulier, nous considérons une série de risques pré-identifiés et les stratégies de mitigation associées ainsi que la valeur de combiner différentes méthodes de collecte de données et de préparer de multiples scénarios d’analyse pour tenir compte d’éventuelles déviations du protocole. L’étude présentée ici a le potentiel de fournir des évidences scientifiques robustes pour soutenir des stratégies de contrôle du choléra plus efficientes dans les contextes difficiles qui sont fortement affectés. Enregistrement de l’essai Cet essai est enregistré sur clinicaltrials.gov ( NCT02928341 , 10 octobre 2016) et a reçu les approbations éthiques de la London School of Hygiene and Tropical Medicine (8913, 10603) ainsi que de l’Ecole de Santé Publique de l’Université de Kinshasa, République Démocratique du Congo (ESP/CE/088/2015).

Abstract Background Cholera remains a major global health challenge. Uvira, in the Democratic Republic of the Congo (DRC), has had endemic cholera since the 1970’s and has been implicated as a possible point of origin for national outbreaks. A previous study among this population, reported a case confirmation rate of 40% by rapid diagnostic test (RDT) among patients at the Uvira Cholera Treatment Centre (CTC). This study considers the prevalence and diversity of 15 enteric pathogens in suspected cholera cases seeking treatment at the Uvira CTC. Methods We used the Luminex xTAG® multiplex PCR to test for 15 enteric pathogens, including toxigenic strains of V. cholerae in rectal swabs preserved on Whatman FTA Elute cards. Results were interpreted on MAGPIX® and analyzed on the xTAG® Data Analysis Software. Prevalence of enteric pathogens were calculated and pathogen diversity was modelled with a Poisson regression. Results Among 269 enrolled CTC patients, PCR detected the presence of toxigenic Vibrio cholerae in 38% (103/269) of the patients, which were considered to be cholera cases. These strains were detected as the sole pathogen in 36% (37/103) of these cases. Almost half (45%) of all study participants carried multiple enteric pathogens (two or more). Enterotoxigenic Escherichia coli (36%) and Cryptosporidium (28%) were the other most common pathogens identified amongst all participants. No pathogen was detected in 16.4% of study participants. Mean number of pathogens was highest amongst boys and girls aged 1–15 years and lowest in women aged 16–81 years. Ninety-three percent of toxigenic V. cholerae strains detected by PCR were found in patients having tested positive for V. cholerae O1 by RDT. Conclusions Our study supports previous results from DRC and other cholera endemic areas in sub-Sahara Africa with less than half of CTC admissions positive for cholera by PCR. More research is required to determine the causes of severe acute diarrhea in these low-resource, endemic areas to optimize treatment measures. Trial registration This study is part of the impact evaluation study entitled: “Impact Evaluation of Urban Water Supply Improvements on Cholera and Other Diarrheal Diseases in Uvira, Democratic Republic of Congo” registered on 10 October 2016 at clinicaltrials.gov Identification number: NCT02928341 .

INTRODUCTION:Cholera is endemic in the Eastern provinces of the Democratic Republic of the Congo since 1978, and Uvira in South-Kivu has been reporting suspected cholera cases nearly every week for over a decade. The clinical case definition for suspected cholera is relatively non-specific, and cases are rarely confirmed by laboratory methods, especially in endemic settings. This may lead to over-estimation of cholera cases and limit effective public health responses. METHODS AND RESULTS:Between April 2016 and November 2017, 69% of the 2,059 patients admitted to the Uvira Cholera Treatment Centre (CTC) were tested for cholera with rapid diagnostic tests (RDTs). Of those admitted as suspected cholera cases, only 40% tested positive for cholera, equivalent to an estimated annual incidence of suspected/confirmed cholera in Uvira of 43.8 and 16.3 cases per 10,000 inhabitants respectively. A multivariable logistic regression indicates that boys aged 2 to 4 years, girls aged 5 to 15 years and adult men are respectively 1.9, 2.1 and 1.8 times more likely to test positive than adult women. On the contrary, boys under 2 are 10 times less likely to test positive. The odds of testing positive also increase as weekly admissions to the CTC rise, with up to a 5-fold increase observed during the weeks with the highest numbers of admissions compared to the lowest ones. Other predictors of cholera confirmation include duration of stay at the CTC, clinical outcome of admission, lower weekly rainfall and area of residence in Uvira, with the northern part of town having the highest confirmation rate. CONCLUSION:Cholera is an on-going public health problem in Uvira but the majority of suspected cases admitted to the CTC were found to be negative for cholera after RDT testing. These findings may have important implications for cholera control strategies in favour of interventions that address cholera and other diarrhoeal diseases alike.