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.

Spatial distribution and risk factors of dengue and Japanese encephalitis virus infection in urban settings: the case of Vientiane, Lao PDR

“…anti‐dengue IgM positive) were more frequent (126 cases, 3.5%) than JE infections (78 cases, 2.1%). This result confirms and extends previous findings of Bounlu et al (1992) and Fukunaga et al (1993). In addition, our results suggest possible differences in the spatial distribution of recent dengue and JEV infections within Vientiane city.…”

“…The IgG seroprevalence of Vientiane adults aged >35 years (84.6%) was similar to past prevalence estimates of 86.4% (78/94) in Attapeu province in 2001 (Peyerl‐Hoffmann et al 2004). Interestingly, our estimates of IgG seroprevalence among children (9.4%) are lower than those reported by Bounlu et al (1992) and Fukunaga et al (1993). However, given the differences in study design, inferences regarding changes in flavivirus transmission intensity based on these studies alone are not warranted.…”

“…The system likely suffers from both over‐reporting due to clinical mis‐diagnosis and under‐reporting due to poor access to health facilities and inadequate data collection. Previous epidemiological studies of dengue transmission in Laos have been restricted to small‐scale serosurveys (less than 300 individuals) either from hospital patients in Vientiane’s Mahosot Hospital in 1990 (Bounlu et al 1992; Fukunaga et al 1993) or from patients in Attapeu province in 2001 (Peyerl‐Hoffmann et al 2004). These studies showed evidence for high levels of endemic transmission with 88% and 79% of individuals, respectively, testing positive for dengue IgG.…”

Prevalence of Endemic Pig-Associated Zoonoses in Southeast Asia: A Review of Findings from the Lao People's Democratic Republic

“…A review of reported JE prevalence in humans in Lao PDR has identified ranges between 0% and 11% in a hospital-based survey in Vientiane of children 15 years of age and under. 70 Other hospital-based surveys in the country have found seroprevalences of up to 75% in Khammouane province, 7% in Luang Namtha, and 4% in Salavan province. 18 Various community level surveys have also found a range of seroprevalences, including 10% and 80% in Khammouane province and Vientiane Municipality, respectively, 71 , 72 and 2.1% in a large-scale serosurvey in Vientiane city.…”

Virological Study on Dengue Epidemic in Vientiane Municipality, Lao PDR, 1994.

“…In 1985 and 1987, large outbreaks of dengue fever (DF) I dengue hemorrhagic fever (DHF) occurred in the urban areas of the Vientiane municipality. In these outbreaks, 1076 and 5232 DF/DHF hospitalized cases were reported to the Vientiane Municipality Health Service, respectively (Bounlu et al, 1992;Fukunaga et al, 1993) . From 1988 to 1993, DF/DHF epidemic did not occur, though several sporadic cases were reported in these areas.…”