Laboratory surveillance of dengue virus in Central Brazil, 1994-2003.

BACKGROUND: In Brazil, dengue endemic and epidemic patterns indicate an upward trend in incidence and hospitalization in the past decade.

OBJECTIVE: To report dengue circulating serotypes from 1994 to 2003 and the role of distinct serotypes on dengue clinical outcomes in Central Brazil.

METHODS: Virological surveillance for dengue cases was conducted in the city of Goiania ( approximately 1,200,000 population) from 1994 to 2003. Samples were tested using dengue IgM antibody (MAC-ELISA) and/or virus isolation. Circulating subtypes and genotypes were identified by reverse transcriptase PCR (RT-PCR) and by restricted site-specific PCR (RSS-PCR) patterns in selected samples.

RESULTS: Adults (87.4%) were the most affected group and dengue fever accounted for the majority of the cases. Laboratory surveillance identified mainly DEN 1 serotype from 1994 to 2002 shifting to a high circulation of DEN 3 in 2003. The ratio of dengue fever to dengue with complications/DHF remained constant following the introduction of DEN 3. Diagnosis of dengue was confirmed in approximately 50% of the suspected cases enhanced by RT-PCR. RSS-PCR patterns for DEN 1 and DEN 3 corresponded to the circulating subtypes in the country.

CONCLUSIONS: The result of virological surveillance did not suggest a major role of infecting DEN 3 serotype in increasing disease severity during its first-year spread in Central Brazil.