Extreme rainfall, poverty and poor sanitation associated to leptospirosis, a climate sensitive disease in Brazil

There are numerous transmissible diseases that are climate-sensitive and associated to lack of treated water and sewage. It may be aggravated by the occurrence of extreme hydrological events, such as droughts or excessive... [ view full abstract ]

There are numerous transmissible diseases that are climate-sensitive and associated to lack of treated water and sewage. It may be aggravated by the occurrence of extreme hydrological events, such as droughts or excessive rainfall, leading to water shortages or floods. These waters when contaminated lead to the emergence of cases of leptospirosis. The aim of this study was to describe the spatial distribution and incidence of leptospirosis in the Brazilian capitals from 2005 to 2014; to identify the epidemiological profile; to verify if there was an association between the incidence of leptospirosis and precipitation patterns, and between the incidence of leptospirosis and socioeconomic variables in the period of this study. This is a descriptive and exploratory study that used exploratory analysis to treat data on the reporting cases of leptospirosis in the brazilian capitals obtained at SINAN (Information System of Notification of Grievences). Rainfall data were obtained from INMET (National Meteorology Institute), and the environmental and socioeconomic data from Atlas Brazil, and demographic data from IBGE (Brazilian Institute of Geography and Statistics). The results showed that Leptospirosis had high incidence in the North and South regions of Brazil. Among the Brazilian capitals, Rio Branco and Amapá had the highest incidence rate. The most affected age group are males in productive phase of life. The most frequent environment of transmission are urban area. Leptospirosis  is related to the low level of schooling in the country places and Capitals. There is a positive and statistically significant correlation (at 1%) between rainfall and leptospirosis incidence. An increase of 10 mm³ in the average rainfall of the Brazilian capitals increases the incidence of leptospirosis by 2%. We concluded that cases of leptospirosis occur more frequently in periods of extreme rainfall, however are also associated with poverty and poor sanitation. Predicting rainfall thresholds  can be useful to prevent flooding and leptospirosis cases.