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Virological study of a dengue type 1 epidemic at Rio de Janeiro
R M Nogueira1, H G Schatzmayr, M P Miagostovich
1Instituto Oswaldo Cruz, Departamento de Virologia, Rio de Janeiro, Brasil.
Abstract:
A dengue outbreak started in March, 1986 in Rio de Janeiro and spread very rapidly to other parts of the country. The great majority of cases presented classical dengue fever but there was one fatal case, confirmed by virus isolation. Dengue type 1 strains were isolated from patients and vectors (Aedes aegypti) in the area by cultivation in A. albopictus C6/36 cell line. The cytopathic effect (CPE) was studied by electron microscopy. An IgM capture test (MAC-ELISA) was applied with clear and reproducible results for diagnosis and evaluation of virus circulation; IgM antibodies appeared soon after start of clinical disease, and persisted for about 90 days in most patients. The test was type-specific in about 50% of the patients but high levels of heterologous response for type 3 were observed. An overall isolation rate of 46.8% (813 virus strains out of 1734 specimens) was recorded. The IgM test increased the number of confirmed cases to 58.2% (1479 out of 2451 suspected cases). The importance of laboratory diagnosis in all regions where the vectors are present is emphasized.
Insights
A 1986 dengue outbreak in Rio de Janeiro was investigated. Diagnostic methods, including IgM capture ELISA, confirmed dengue virus circulation and aided case identification.
Area of Science:
- * Virology
- * Epidemiology
- * Immunology
Background:
- * A significant dengue outbreak occurred in Rio de Janeiro in 1986, rapidly spreading nationwide.
- * Classical dengue fever was prevalent, with one confirmed fatal case.
- * Dengue virus type 1 strains were identified in patients and Aedes aegypti vectors.
Purpose of the Study:
- * To investigate the dengue outbreak in Rio de Janeiro.
- * To evaluate the efficacy of diagnostic methods for dengue virus detection and serological surveillance.
- * To characterize the isolated dengue virus strains and their epidemiological impact.
Main Methods:
- * Isolation of dengue virus strains from patient samples and Aedes aegypti vectors using A. albopictus C6/36 cell lines.
- * Electron microscopy to study the cytopathic effect (CPE) of the virus.
- * Application of an IgM capture test (MAC-ELISA) for diagnosis and assessment of virus circulation.
Main Results:
- * Dengue type 1 strains were successfully isolated and identified.
- * The MAC-ELISA demonstrated clear and reproducible results, with IgM antibodies persisting for approximately 90 days.
- * The IgM test increased confirmed dengue cases by 11.4% (from 46.8% isolation rate to 58.2% confirmed cases).
Conclusions:
- * The IgM capture test is a valuable tool for dengue diagnosis and monitoring virus circulation.
- * Laboratory diagnosis is crucial in regions with established dengue vectors.
- * Further research on heterologous responses in MAC-ELISA is warranted.