Risk factors for transmission of Salmonella Typhi in Mahama refugee camp, Rwanda: a matched case-control study.

Introduction: In early October 2015, the health facility in Mahama, a refugee camp for Burundians, began to record an increase in the incidence of a disease characterized by fever, chills and abdominal pain. The investigation of the outbreak confirmed Salmonella Typhi as the cause. A case-control study was conducted to identify risk factors for the disease. Methods: A retrospective matched case-control study was conducted between January and February 2016. Data were obtained through a survey of matched cases and controls, based on an epidemiological case definition and environmental assessment. Odd ratios were calculated to determine the risk factors associated with typhoid fever. Results: Overall, 260 cases and 770 controls were enrolled in the study. Findings from the multivariable logistic regression identified that having a family member who had been infected with S. Typhi in the last 3 months (OR 2.7; p < 0.001), poor awareness of typhoid fever (OR 1.6; p = 0.011), inconsistent hand washing after use of the latrine (OR 1.8; p = 0.003), eating food prepared at home (OR 2.8; p < 0.001) or at community market (OR 11.4; p = 0.005) were risk factors for typhoid fever transmission. Environmental assessments established the local sorghum beer and yoghurt were contaminated with yeast, aerobic flora, coliforms or Staphylococcus. Conclusion: These findings highlight the need of reinforcement of hygiene promotion, food safety regulations, hygiene education for beverage and food handlers in community market and intensification of environmental interventions to break the transmission of S. Typhi in Mahama.