Clinical, epidemiologic, and virologic features of dengue in the 1998 epidemic in Nicaragua

From July to December 1998, a hospital- and health center-based surveillanc e system for dengue was established at selected sites in Nicaragua to bette r define the epidemiology of this disease. Demographic and clinical informa tion as well as clinical lab oratory results were obtained, and virus isola tion, revers e transcriptase-polymerase chain reaction, and serologic assay s were performed. World Health Organization criteria were used to classify disease severity; however, a number of patients presented with signs of sho ck in the absence of thrombocytopenia or hemoconcentration. Therefore, a ne w category was designated as "dengue with signs associated with shock" (DSA S). Of 1,027 patients enrolled in the study, 614 (60%) were laboratory-conf irmed as positive cases; of these, 268 (44%) were classified as dengue feve r (DF); 267 (43%) as DF with hemorrhagic manifestations (DFHem); 40 (7%) as dengue hemorrhagic fever (DHF); 20 (3%) as dengue shock syndrome (DSS); an d 17 (3%) as DSAS. Interestingly, secondary infection was not significantly con-elated with DHF/DSS, in contrast to previous studies in Southeast Asia . DEN-3 was responsible for the majority of cases, with a minority due to D EN-2; both serotypes contributed to severe disease. As evidenced by the ana lysis of this epidemic, the epidemiology of dengue can differ according to geographic region and viral serotype.