Dengue 3 Virus Circulation in Costa Rica, 1994-1997

Abstract

The circulation of the dengue 3 serotype in Costa Rica from October 1993 through December 1997 are presented in this report. The results are based on the laboratory analysis of the samples received and processed in the National Reference Center for Dengue and its correlation with the severe clinical manifestations and epidemiological data with relation to the cases studied within this period. All sera were analyzed to evaluate the presence of IgM specific for dengue by ELISA. The presence of primary or secondary infections was determined by using an inhibition of hemmaglutination assay. Viral isolation was carried out using mosquito C6/36 cells. Positive cultures and serotypes were confirmed by immunofluorescence procedures. Some of the sera were also analyzed by PCR to confirm the presence of viral genomes.

The first epidemic of dengue started in Costa Rica in October 1993 when cases of dengue caused by serotypes I, 2 and 4 (79%, 10.5% and 10.5% of the isolates, respectively) were documented in Puntarenas and Guanacaste (Central Pacific Region). Data showed that although dengue 3 serotype was initially identified in 1994 in a single case, an increased circulation of this serotype was confirrned in 1995 in cases coming from four of the Health Regions of the country. Genetic analysis carried out at the CDC in Puerto Rico revealed a close relationship of these strains with those isolated in India and Sri Lanka (group Ill). The first two confirmed cases of dengue hemorrhagic fever (DHF) were also reported in this year. Later, in May 1996, after a relative decline in the activity of the disease, new dengue 3 isolates were

most of the cases, including a fatal in the province of Limon (Huetar majority (72%) corresponding to the rest (28%) were identified as dengue 3.

During 1997, an important increase of the dengue 3 serotype the Central Pacific Region (98% of the 2 % of the serotype I) together with a the report of hemorrhagic manifestations death. Nonetheless, the expected clinical in other areas have not been described as a consequence of the combination of low number of secondary infections, the infection, the time between the first with different dengue serotypes, among results from this report suggest that an program should be kept to detect cases of syndrome that can occur as a consequence dengue serotype 3 after the circulation of other types.