Dengue infection in Paracambi, State of Rio de Janeiro, 1990-1995.

ABSTRACT

PIP: Dengue virus type 1 (DEN-1) was first isolated in Rio de Janeiro, Brazil, in 1986. In 1990, another serotype, DEN-2, was introduced. Since then, both strains have co-circulated in the state, especially during the rainy season. This study assessed the prevalence of dengue virus infection in Paracambi--a periurban municipality of Rio de Janeiro with environmental conditions that allow natural breeding of Aedes aegypti and A. albopictus. In 1990-91, 1209 dengue cases were reported in the municipality and laboratory studies confirmed 21 cases of dengue hemorrhagic fever. Serologic samples collected in 1994 from 370 randomly selected schoolchildren 4-16 years of age revealed hemagglutination inhibition test antibody titers equal to or greater than 1/20 to DEN-1 and/or DEN-2 in 145 children (39.2%). The geometric averages of antibody titers were 1/75 for DEN-1 and 1/30 for DEN-2. Entomological surveillance revealed declines in the house index of A. aegypti to 2.0% or under by 1995, while the index of A. albopictus remained at 0.6-7.4%. The decline in A. aegypti was accompanied by a dramatic reduction in dengue virus cases in 1991-94. However, as a result of the interruption of vectors measures control in 1994, the number of dengue cases has shown an upward trend since 1995.