A protracted cholera outbreak in Nairobi City County associated with mass gathering events, Kenya, 2017

Cholera continues to cause many outbreaks in low and middle-income countries due to inadequate water, sanitation, and hygiene services. We describe a protracted cholera outbreak in Nairobi City County (NCC), Kenya in 2017. We reviewed the cholera outbreak line lists from NCC in 2017 to determine its extent and factors associated with death. A suspected case of cholera was any person aged >2 years old who had acute watery diarrhea, nausea, or vomiting, whereas a confirmed case was where Vibrio cholerae was isolated from the stool specimen. We summarized cases using for continuous variables and proportions for categorical variables. Associations between admission status, sex, age, residence, time to care seeking, and outbreak settings; and cholera associated deaths were assessed using odds ratio (OR) with 95% confidence interval (CI). Of the 2,737 cholera cases reported, we analyzed 2,347 (85.7%) cases including 1,364 (58.1%) outpatients, 1,724 (73.5%) not associated with mass gathering events (MGEs), 1,356 (57.8%) male and 2,202 (93.8%) aged >=5 years, and 35 deaths (case fatality rate: 1.5%). Cases were reported from all the Sub Counties of NCC with an overall county attack rate of 50 per 100,000 people. Vibrio cholerae Ogawa serotype was isolated from 78 (34.8%) of the 224 specimens tested and all isolates were sensitive to tetracycline and levofloxacin but resistant to amikacin. The odds of cholera-related deaths was lower among outpatient cases (aOR: 0.35; [95% CI: 0.17- 0.72]), age >=5 years old (aOR: 0.21 [95% CI: 0.09-0.55]), and MGEs (aOR: 0.26 [95% CI: 0.070.91]) while threefold higher odds among male (aOR: 3.04 [95% CI: 1.30-7.13]). NCC experienced a protracted and widespread cholera outbreak with a high case fatality rate in 2017. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The author(s) received no specific funding for this work. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Not Applicable The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Approval to access the line list data was sought from the Kenya Ministry of Health’s Division of Disease Surveillance and Response. The study used de-identified data that had been collected during outbreak response activities and therefore informed consent was not sought. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Not Applicable I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Not Applicable I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Not Applicable All relevant data are within the manuscript and its Supporting Information files