The objective of the study is to analyze the temporal trend of leptospirosis
incidence, according to rainfall levels in Santa Catarina, according to
seasonality, from 2005 to 2015. This is an ecological study of time series, with
date of leptospirosis, rainfall levels and population. The incidence rates of
leptospirosis, relative excess of incidence, Pearson's correlation coefficient
(r) and an angular coefficient (β) were analyzed from the linear regression
adjustment, with a 5% significance level. Distribution of leptospirosis cases,
rainfall levels and cases reason/rainfall levels, stratified by month of
occurrence were presented. There were 5,274 cases of leptospirosis, with the
monthly average being 439 cases, ranging from 211 in September to 770 in
January. The mean rate of leptospirosis was 7.03 per 100,000 habitants. The
average rainfall level was 158.68 mm, with the lowest levels occurring in
August, average of 124.9 mm, and the highest in January average of 213.20 mm.
The positive correlation between leptospirosis rates and rainfall levels, during
the period from January to December (r = 0.68, p = 0.023), indicates a positive
temporal association between the amount of rainfall and the cases of the
disease. The disease occurred all year round and presented a distinct
seasonality from October to March.