Epidemiology of Human Leptospirosis in the Central Region of Veracruz, Mexico

Aims: To epidemiologically characterize patients confirmed as cases of leptospirosis in Central Veracruz, Mexico based on official records.
Study Design: Descriptive retrospective study.
Place and Duration of Study: Sanitary District No. VIII, Health Ministry in central Veracruz, Mexico from January 2007 to December 2011.
Methodology: Data analysis was performed on official records of clinical cases suggestive of human leptospirosis and confirmed by microscopic agglutination test plate within the study period. Variables considered for analysis included filing date, patient’s socio-demographic characteristics, care center, test result and identified serovars. Incidence rate was calculated as the number of cases per 100000 inhabitants. Chi-square was used to compare categories in Minitab v. 13 and a significance level of P = .05 was defined.
Results: There were 1403 suspected cases of leptospirosis from 14 municipalities in central Veracruz, of which 42.4% (595) resulted positive for leptospirosis. The municipalities with the highest number of confirmed cases in the period were: Veracruz (56%, 333 cases), La Antigua (14%, 83 cases) and Boca del Río (7.7%, 46 cases). La Antigua showed an unusually high incidence rate (65.1). Years with the highest number of cases were 2010 (257 cases) and 2011 (94 cases).Months with the highest number of cases were October (156 cases, 26.2%), and to a lesser extent February (57, 9.6%), August (55, 9.2%), January (53, 8.9%) and September (53, 8.9%) detecting a highly significant statistical difference between months (P=.01). The single month with the highest number of cases in the study period was October 2010, in which 120 positive cases of leptospirosis were recorded, which is coincidental with the aftermath of Hurricane Karl that hit the region in September 2010. Most affected age groups were 21-30 years (125 cases, 21.1%), 11-20 (104, 17.5%) and 31-40 (92, 15.5%), but no statistically significant difference between these groups was identified (P = .4). Male subjects (727 cases, 51.82%) were more affected than females (676, 48.18%), but this difference was not significant (P = .05).
Conclusion: We conclude that leptospirosis has a strong presence in the human population in central Veracruz, Mexico.