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[Outbreak of human leptospirosis after a flood in Reconquista, Santa Fe, 1998]
N B Vanasco1, S Fusco, J C Zanuttini
1Instituto Nacional de Enfermedades Respiratorias E. Coni, ANLIS Dr. Carlos G. Malbrán, Argentina. jlotters@fbcb.unl.edu.ar
Abstract:
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.
Insights
An outbreak of leptospirosis occurred in Santa Fe province following heavy rainfall and flooding. The study confirmed 40 cases, with infection prevalent in men aged 21-40, presenting with fever, headache, and myalgias.
Area of Science:
- Epidemiology
- Infectious Diseases
- Public Health
Background:
- Leptospirosis is a zoonotic disease of global concern.
- Environmental factors, such as heavy rainfall and flooding, are known to increase leptospirosis transmission risk.
- An unusual number of leptospirosis cases were reported in Santa Fe province, Argentina, starting April 1998.
Purpose of the Study:
- To investigate a potential leptospirosis outbreak in Santa Fe province.
- To identify the infecting serogroups and risk factors associated with the cases.
Main Methods:
- A case-control study was conducted involving 122 patients.
- Screening tests included macroscopic agglutination test (MAT) with 10 serotypes of *L. interrogans* and ELISA.
- Confirmed cases were analyzed for clinical symptoms, demographic data, and potential exposure to environmental risk factors.
Main Results:
- Leptospirosis was confirmed in 40 out of 122 patients.
- The most frequent infecting serogroups were Icterohaemorrhagiae, Ballum, Sejroe, Pomona, and Canicola.
- Infection prevalence was higher in men aged 21-40 years. Common symptoms included headache, fever, and myalgias.
- All cases occurred after significant rainfall and during a period of area inundation, suggesting a strong link to flooding.
Conclusions:
- The clinical presentation, temporal distribution, and geographical localization strongly suggest a leptospirosis outbreak in the studied area.
- Environmental factors, particularly flooding following heavy rains, were identified as a significant risk factor.
- Public health interventions should consider environmental monitoring and public awareness campaigns in flood-prone regions.