Cholera Outbreak Investigation at a Secondary School in Kabwe, Zambia, April 2025: A Case-Control Study

Abstract

Introduction: Cholera remains a significant public health threat in Zambia, with outbreaks commonly linked to inadequate water, sanitation, and hygiene (WASH) systems. In March 2025, a cholera outbreak was reported in Kabwe District, primarily affecting David Ramusho Secondary School and surrounding Mine Compound. This investigation aimed to identify the source, assess transmission dynamics, and evaluate the response to inform future interventions. Methods: We conducted a case control study involving 70 cholera cases and 70 matched community controls. Cases were defined by standard WHO criteria, and controls were selected from unaffected individuals within the same neighborhoods. Data collection included structured interviews, environmental assessments, and review of surveillance and facility records. Logistic regression analysis was performed to identify risk factors. Results: Indicated that reliance on unsafe water sources (adjusted OR=3.20, 95% CI: 1.50–6.80), use of pit latrines or absence of toilets (aOR=2.80, 95% CI: 1.30–6.00), and failure to treat drinking water (aOR=4.00, 95% CI: 1.70–9.40) were significantly associated with cholera infection. Conversely, boiling or chlorination of water was protective. Although oral cholera vaccine (OCV) coverage was high (71.4% among both cases and controls), no significant protective effect was observed in this outbreak. Demographic factors such as age and tertiary education initially appeared protective but were not significant after adjustment. Most cases were students, highlighting schools as critical settings for cholera transmission. Conclusion: The Kabwe outbreak underscores the continued vulnerability of peri-urban populations to cholera due to unsafe water and poor sanitation. The 7-1-7 response framework was applied, with timely detection and notification achieved; however, challenges in sustained control and community-level WASH improvements were evident. We recommend strengthening household water treatment, improving school and community sanitation, enhancing health education campaigns, and instituting routine water quality monitoring. These findings emphasize the need for integrated WASH interventions and sustained public health preparedness to prevent future cholera outbreaks in Kabwe and similar urban settings.