Laboratory surveillance of dengue virus in Central Brazil, 1994–2003

BackgroundIn Brazil, dengue endemic and epidemic patterns indicate an upward trend in incidence and hospitalization in the past decade.ObjectiveTo report dengue circulating serotypes from 1994 to 2003 and the role of distinct serotypes on dengue clinical outcomes in Central Brazil.MethodsVirological surveillance for dengue cases was conducted in the city of Goiania (∼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.ResultsAdults (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 ∼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.ConclusionsThe 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.