RESUMO
Since April of 1998 a high number of leptospirosis cases were detected, coming from the area of Reconquista Central Hospital in Santa Fe province. Since January of that year a notable increase in rainfall and river levels was observed causing inundation. As screening test, macroscopic agglutination (MAT) using 10 serotypes of L. interrogans. Among the 122 patients studied 71 were TR positive and 52 were also ELISA positive, leptospirosis diagnosis being confirmed in 40 of them. Five infecting serogroups were identified: Icterohaemorrhagiae (7/40), Ballum (5/40), Sejroe (3/40), Pomona (3/40) and Canicola (2/40). In the remaining cases (20/40), co-agglutinins were found at the same titer against two or more serotypes of leptospires. Infection prevalence was higher in men and productive age (21 to 40 years). The clinical symptoms more frequently observed were headache, fever and myalgias. All cases occurred after the rains and in the period when the area was flooded. Their clinical presentation, time distribution, geographical localization and high frequency of contact with the risk factor inundation could indicate that, independently of search activities, there was an outbreak.