Seasonality of Visceral Leishmaniasis in Imperatriz-MA: Correlation Between Rainfall and Cases in the Post-Rainy Period (2015–2023)

Objective: This study aimed to analyze the relationship between rainfall indexes and the incidence of confirmed cases of Visceral Leishmaniasis (VL) in Imperatriz, Maranhão, Brazil, from 2015 to 2023, identifying seasonal patterns and implications for epidemiological surveillance. Theoretical Framework: The research is grounded in prior studies that associate climatic factors, such as temperature and rainfall, with the epidemiological behavior of VL. Contributions from Margonari et al. (2012), Oliveira et al. (2016), and Silva et al. (2018) are highlighted, demonstrating how seasonality influences vector dynamics and disease transmission. Method: This is an epidemiological, descriptive, and retrospective study using secondary data from the Notifiable Diseases Information System (SINAN) and the National Institute of Meteorology (INMET). The data were structured in monthly time series and analyzed with a comparative and correlational approach. Results and Discussion: A total of 565 VL cases were recorded during the analyzed period. A consistent pattern was identified: the highest number of cases occurred during the driest months (May to August), following the months with the highest rainfall (January to March). A 2 to 3-month lag between rainfall peaks and case surges reinforces the influence of the vector's reproductive cycle. Research Implications: The findings suggest the need to intensify vector control and public health surveillance during the post-rainy season, incorporating climate data into prevention strategies. Originality/Value: This study contributes by highlighting a strong seasonal correlation between climate and VL, offering support for more effective public policies in endemic areas.