Outbreak investigation of cholera in Birgunj, Nepal: An unmatched case-control study

Background Cholera remains a persistent global health threat. Although it is preventable and treatable, it has disproportionality affected vulnerable population lacking water and sanitation particularly among the low-middle income countries. The recent cholera outbreak was seen in Birgunj metropolitan city, Madhesh province, eastern part of Nepal in August 2025. Out of one thousand one hundred fourteen, hundreds of hospitalized within days, exposed critical gaps in water safety, sanitation and community awareness. The study aims to investigate cholera outbreak. Methods The population-based unmatched case-control study with 1:1 ratio, 63 confirmed cholera cases and 63 community controls from the most affected wards of Birgunj were enrolled in the study. Data was collected though face-to-face interviews using a structured questionnaire on WHO guidelines, alongside secondary outbreak records. Statistical analysis with SPSS included descriptive measures, chi-square tests and binary logistic regression to identify significant risk factors for cholera. Results The study revealed that limited awareness about cholera complications (OR: 2.30, 95% CI: 0.64–8.28) and preventive measures (OR: 2.87, 95% CI: 1.23–6.73) significantly increased the risk of cholera among the participants. The cholera risk was strongly shaped by socio-demographic and behavioral factors. The participants aged 5–49 years (OR: 2.81, 95% CI: 1.45–6.92), individuals from Muslim ethnic groups (OR: 12.26, 95% CI: 4.98–30.14), and those without formal education (OR: 8.85, 95% CI: 2.57–30.46) were disproportionately affected. Household and community practices such as consuming street food (OR: 11.47, 95% CI: 4.86–27.07), relying on untreated public tap water (OR: 19.77, 95% CI: 4.40-88.76), unsafe stool disposal (OR: 17.95, 95% CI: 4.64–66.61), cross-connections (OR: 2.461, 95% CI: 1.49–4.04) significantly increased risk of cholera. The effective preventive measures improving sanitation and hygiene practices, strengthening community awareness through education and behavioral change and long-term measures like oral cholera vaccination, regular water chlorination and active surveillance. Conclusion Cholera in Birgunj was influenced by social, behavioral and environmental factors, indicating the urgent need for stronger community awareness and behavioral change, safe water and sanitation practices.