THE EPIDEMIOLOGY OF DENGUE VIRUS-INFECTION AMONG URBAN, JUNGLE, AND RURAL POPULATIONS IN THE AMAZON REGION OF PERU

The first confirmed outbreak of dengue fever in Peru occurred during 1 990 in Iquitos, a city of approximately 300,000 residents in the Amazo n region. Because of the apparent establishment of endemic transmissio n of this mosquito-borne viral disease following the outbreak, epidemi ologic studies were initiated in 1992. Blood specimens and data on dem ographic, environmental, and medical history factors were collected fr om volunteers in an urban sector of Iquitos, in a rural area on the ou tskirts of Iquitos, and in three nearby jungle communities. A follow-u p blood specimen was obtained approximately one year later from a samp le of subjects. Sera were tested for dengue IgG antibody by an enzyme- linked immunosorbent assay, and specificity was verified using a plaqu e-reduction neutralization test. Dengue antibody prevalence was 66% in the urban population, 26% in the rural population, and 32-67% in the three jungle areas. A significant association was found between age an d antibody prevalence, with a steady increase in prevalence from 18% a mong subjects less than five years of age to greater than 90% for subj ects more than 50 years old. Increased antibody prevalence also was as sociated with urban and jungle residence and with a piped source of ho usehold drinking water. Seroconversions were documented in four of fiv e surveyed communities. These results indicate that dengue virus trans mission continues in and around Iquitos and suggest that transmission also occurred prior to the 1990 epidemic.