Fifteen years of human leptospirosis in São Paulo, Brazil

Abstract

Objective: Leptospirosis is a worldwide zoonosis caused by pathogenic Leptospira spp. The aim of this study was to report theincidence of leptospirosis from 1998 to 2012 in the state of São Paulo, Brazil to show the importance of human leptospirosis andto describe some epidemiological characteristics.

Methods: From January 1998 to December 2012, sera from patients with suspected leptospirosis were analyzed. The microscopicagglutination test (MAT) was used for serological investigations and MLST, serotyping and PFGE methods for the identificationof leptospires. The descriptive seasonal analysis was performed with Excel Microsoft version 2007. Pearson’s correlation wasused to assess the association between rainfall and the number of cases.

Results: Among 22,795 serum samples, 2,430 cases of leptospirosis were laboratory confirmed, giving an average incidence rateof 1.35/100,000 inhabitants. Of these patients, 2,032 (83.62%) were male with a predominance in the age groups of 21-50 years.The highest incidence and rainfall were from December to April. There was correlation between the rainfall and the number ofcases. Icterohaemorrhagiae was the predominant serogroup.

Conclusions: This study shows that leptospirosis is a seasonal disease in São Paulo with most cases occurring during the rainyseason, and thus, will continue to be a disease of public health importance.