A seroepidemiological study of dengue and Japanese encephalitis virus infections in Vientiane, Lao PDR.

Abstract

A total of 141 serum specimens from inhabitants in eight age groups in Vientiane, Lao PDR was examined to estimate the neutralizing anitibody levels to dengue (DEN) and Japanese encephalitis (JE) viruses. From the analyses of the results of neutralization (N) tests, the following conclusions were drawn about the prevalences of DEN and JE viruses in Vientiane : (1) The percentage incidences of N antibodies to DEN 1-4 viruses increased with age, but the incidences of N antibodies to DEN-3 and DEN-4 were lower than those to DEN-1 and DEN-2, which reached 100% by the age of 21-30 years old. (2) The percentage incidence of N antibody to JE virus was similar to those to DEN-3 and DEN-4. (3) The geometric mean titer of N antibody to DEN-2 was highest among four serotypes in every age group, indicating that, in the past, DEN-2 virus was most prevalent. (4) By the age of 15 years old, the majority of the inhabitants (88.2%) in Vientiane were infected with two or more serotypes of DEN viruses and most children seem to be exposed first to DEN viruses and later to JE virus.