Investigation of a suspected cholera outbreak within a closed community of trainees at a college in Hammanskraal, Gauteng Province, South Africa, June 2023

Cholera, as defined by the US Center for Disease Control and Prevention (CDC), is an acute diarrhoeal disease caused by infection of the intestine with the toxin-producing Vibrio cholerae serogroup O1 or O139 bacterium. We investigated a suspected outbreak of cholera at a training college with the aim of determining the magnitude of the outbreak and identifying possible risk factors. We conducted a retrospective cohort study including all persons attending training or living in the college premises between 8 May and 1 June 2023. A case was defined as anyone attending training courses on campus who experienced diarrhoea and/or vomiting between 8 May and 1 June 2023. Data were collected through an online questionnaire. R Studio was used to calculate attack rates and risk ratios to identify possible risk factors associated with illness. Two hundred and thirty-eight participants completed the online questionnaire on 1 June 2023, of which 37% (88/238) reported illness during the study period. The median age of cases was 35 years with a predominance of males (67/88; 76%). Risk factors associated with illness included brushing teeth with tap water (RR = 1.8; CI = 1.2–2.6), sex (RR = 1.6; CI = 1.1–2.5) and unavailability of hand washing soap in the bathrooms (RR = 1.6; CI = 1.2–2.3). Eating food bought outside the college (RR = 0.5; CI = 0.4–0.8) and availability of hand washing soap in the bathrooms were protective against illness (RR = 0.4; CI = 0.3–0.7). This diarrheal disease outbreak was likely caused by multiple pathogens including Vibrio cholerae, a pattern usually seen when there is suspected/possible fecal contamination of drinking water sources. Recommendations included ongoing provision of safe water to the trainees attending courses at the college and anyone living in the college until such time that the municipal drinking water was declared safe for drinking by the responsible stakeholders.