Circulation of Dengue Viruses in North-Western Peru, 2000-2001

Prior to 2000, only DEN-1 and the American genotype DEN-2 viruses were isolated in Peru. During the dengue outbreak from May 2000 to May 2001 in the North-west departments of Peru, clinical data and blood samples were obtained from 1,652 patients who presented clinical manifestations comparable with those of dengue. Virus genome isolations were made from 278 (16.8%) of the samples. Serotype-specific monoclonal antibodies and polymerase chain reaction (PCR) were used to type isolations. The genotype of the majority of the DEN-2 isolations was determined by the restriction fragment length polymorphism (RFLP) analysis. Members of each serotype and two genotypes of DEN-2 virus were isolated: DEN-1 (n=93); Asian genotype DEN-2 (n=104); American genotype DEN-2 (n=1); DEN-2 genotype not determined (n=53); DEN-3 (n=25); and DEN-4 (n=2). Representativ es of each serotype, and genotype for DEN-2, were confirmed by partial sequence analysis. Dengue antibodies as determined by Plaque Reduction Neutralization Test (PNT) were present in the acute serum from the single DHF Grade-II patient, in 19 of 31 (61%) acute sera from patients with DHF Grade-I and in 3 of 45 (7%) acute sera of DF patients, suggesting an association between pre-existing dengue antibody and disease severity.