Hepatitis A outbreak associated with food consumption and sexual practices: a case-control study, Curitiba, Paraná, 2024

OBJECTIVE: To identify factors associated with hepatitis A infection in Curitiba, Paraná, Brazil. METHODS: This is a case-control study with individuals aged ≥16 years, living in Curitiba, Paraná, selected from the municipal laboratory base. We defined as cases individuals with reactive serology for hepatitis A and as controls those with non-reactive serology, from November 1st, 2023 to May 29th, 2024. Data were collected using a self-administered questionnaire. Bivariate analysis was performed followed by hierarchical logistic regression to estimate odds ratio (OR) and respective 95% confidence intervals (95%CI). RESULTS: A total of 242 individuals participated (121 cases and 121 controls). The cases had a higher proportion of males (64.5% vs. 52.5%), Whites (78.5% vs. 63.8%), and men who have sex with men (MSM) (25.6% vs. 12.4%) when compared to controls. In the adjusted multivariate model, hepatitis A infection maintained a significant association with raw fish consumption (aOR 2.54; 95%CI 1.39; 4,64; p-value 0.002) and with MSM (aOR 2.38; 95%CI 1.10; 4,85; p-value 0.027). Not eating out had a protective effect (aOR 0.22; 95%CI 0.08; 0,62; p-value 0.004). CONCLUSION: In the context of the investigated outbreak, hepatitis A infection was associated with the consumption of raw fish and identification as MSM, while not eating out was a protective factor. These findings indicate the relevance of prevention measures related to both food security and specific population groups, especially in scenarios of urban outbreaks.