Epidemiological study of Japanese encephalitis virus in Vientiane, Lao PDR, in 1990s.

Phylogenetic analysis of Japanese encephalitis virus (JEV) was conducted using core-premembrane and envelope gene sequence data of two strains from Vientiane, Lao People's Democratic Republic, in 1993 and five from Okinawa, Japan, in 2002 and 2003, and previously published strains. The two Vientiane strains designated as LaVS56 and LaVS145 belonged to genotype 1 (G1) and the same subcluster of G1 as Australian strain in 2000, Thai strains in 1982-1985 and 2004-2005, and Vietnamese strain in 2005, but were distinct from the subcluster of recently distributing G1 strains widely in Asia including Okinawan strains and recent Lao strain in 2009. These clusters with own distinct distributions indicated involvements of different mechanisms and routes of spreading viruses and clarified that Australian G1 strain is from Southeast Asia, not from East Asia. Both Vientiane strains were antigenically close to P19-Br (G1, isolate, Thailand), but distinct from Nakayama (G3, prototype strain, Japan), Beijing-1 (G3, laboratory strain, China), and JaGAr#01 (G3, laboratory strain, Japan), demonstrated by cross-neutralization tests using polyclonal antisera. These results together with seroepidemiologic study conducted in Vientiane strongly suggest that diversified JEV cocirculated there in early 1990s.

Oral health behavior of children and guardians' beliefs about children's dental caries in Vientiane, Lao People's Democratic Republic (Lao PDR).

Dental caries is considered a major health problem among schoolchildren in Lao People's Democratic Republic (Lao PDR). According to Health Belief Model (HBM)-based research, children's oral health behavior can be determined by their guardians' beliefs. This study aimed to describe children's oral health behavior and its association with childhood dental caries, as well as to assess associations between children's tooth-brushing behavior and guardians' beliefs in an urban area of Lao PDR, using HBM. Data were collected from ten primary schools in the Sisattanak district, the Vientiane capital, between 2013 and 2014. Ten dentists with the help of dental hygienists and schoolteachers conducted dental health check-ups at the schools that diagnosed dental caries based on visual inspection. They also conducted a questionnaire-based survey with the schoolchildren's guardians to collect data including socio-economic and demographic information, their children's oral health behavior, and guardians' beliefs derived from HBM, including perceived susceptibility to and perceived severity of child dental caries, perceived benefit of and perceived barrier to child's tooth brushing, and self-efficacy in making their children brush their teeth twice daily. A mixed-effects logistic regression model assessed the association between dental caries and children's oral health behavior and between children's tooth-brushing behavior and guardians' beliefs. Data from 1161 of 1304 (89.0%) children registered at the schools were used. The prevalence of dental caries was 82%. Children who brushed their teeth ≥ twice/day were significantly less likely to have dental caries than those brushing once or seldom (OR: 0.64, 95% CI: 0.45 to 0.91). The number of children who brushed twice daily also significantly increased with the increased level of guardians' self-efficacy (OR: 2.14, 95% CI: 1.91 to 2.41). In conclusion, childhood dental caries was associated with daily tooth brushing. Children's tooth-brushing behavior was associated with guardians' self-efficacy in making their children brush twice daily.