Gender differences in Leptospira exposure risk, perceptions of disease severity, and high-risk behaviours in Salvador, Brazil: A cross-sectional study

Vulnerability to climate hazards and infectious diseases is not gender-neutral, meaning that men, women, and other gender identities experience different risks. Leptospirosis is a zoonotic climate-sensitive infectious disease caused by the bacteria Leptospira and is transmitted to humans through contact with infected animals or contaminated environments, particularly soil and floodwater. Globally, studies report a higher risk of leptospiral infection among men than women, a trend also observed in Salvador, Brazil; however, the factors driving this difference are poorly understood. This study aimed to investigate how Leptospira exposure differs between men and women living in urban informal settlements in Salvador. We conducted a cross-sectional serosurvey among 761 adults (280 men and 481 women) in four communities previously identified as high-risk by surveillance data. Using a causal inference approach and a two-part sex-disaggregated analysis, we applied logistic regression models to examine: (1) the association between perceived severity and high-risk behaviours with Leptospira seropositivity, and (2) the association between perceived severity with high-risk behaviours. Seroprevalence was 14.6% (95% CI: 10.5%-18.8%) in men and 9.4% (95% CI: 6.7%-12.0%) in women. Men who perceived leptospirosis as extremely serious had lower odds of being seropositive (OR: 0.38, 95% CI: 0.15-0.99), walking through sewage (OR: 0.41, 95% CI: 0.17-1.00), and walking barefoot outside (OR: 0.24, 95% CI: 0.08-0.76) compared with men who perceived leptospirosis as less serious. These associations were not observed in women and differed across age groups in men. Behaviours were not associated with seropositivity in either gender. Our results identify perceived severity as a potential driver of high-risk behaviours and exposure in men, indicating perceptions as targets for health promotion programs, while also highlighting evidence gaps in understanding exposure risks among women. As the first sex-disaggregated study investigating Leptospira exposure risks, we advocate for a gendered lens in future studies to understand gender-specific risks.