Risk factors for mosquito house entry in the Lao PDR.

BACKGROUND: Construction of the Nam Theun 2 hydroelectric project and flooding of a 450 km(2) area of mountain plateau in south-central Lao PDR resulted in the resettlement of 6,300 people to newly built homes. We examined whether new houses would have altered risk of house entry by mosquitoes compared with traditional homes built from poorer construction materials. METHODOLOGY/PRINCIPAL FINDINGS: Surveys were carried out in the Nam Theun 2 resettlement area and a nearby traditional rice farming area in 2010. Mosquitoes were sampled in bedrooms using CDC light traps in 96 resettlement houses and 96 traditional houses and potential risk factors for mosquito house entry were recorded. Risk of mosquito house entry was more than twice as high in traditional bamboo houses compared with those newly constructed from wood (Putative Japanese Encephalitis (JE) vector incidence rate ratio (IRR) = 2.26, 95% CI 1.38-3.70, P = 0.001; Anopheline IRR = 2.35, 95% CI: 1.30-4.23, P = 0.005). Anophelines were more common in homes with cattle compared against those without (IRR = 2.32, 95% CI: 1.29-4.17, P = 0.005).Wood smoke from cooking fires located under the house or indoors was found to be protective against house entry by both groups of mosquito, compared with cooking in a separate room beside the house (Putative JE vector IRR = 0.43, 95% CI: 0.26-0.73, P = 0.002; Anopheline IRR = 0.22, 95% CI: 0.10-0.51, P<0.001). CONCLUSIONS/SIGNIFICANCE: Construction of modern wooden homes should help reduce human-mosquito contact in the Lao PDR. Reduced mosquito contact rates could lead to reduced transmission of diseases such as JE and malaria. Cattle ownership was associated with increased anopheline house entry, so zooprophylaxis for malaria control is not recommended in this area. Whilst wood smoke was protective against putative JE vector and anopheline house entry we do not recommend indoor cooking since smoke inhalation can enhance respiratory disease

Strategic success for hydropower in Laos.

International audienc

Molecular evidence of Opisthorchis viverrini in infected bithyniid snails in the Lao People's Democratic Republic by specific hybridization probe-based real-time fluorescence resonance energy transfer PCR method.

Naturally occurring bithyniid snails, Bithynia siamensis goniomphalos (Prosobranchia: Bithyniidae), and their intermediate hosts were sampled from Khammouane Province, the Lao People's Democratic Republic, and the prevalence of the carcinogenic human liver fluke, Opisthorchis viverrini, was examined. The presence of O. viverrini cercariae in snails was examined by cercarial shedding test and then confirmed by specific hybridization probe-based real-time fluorescence resonance energy transfer (FRET) PCR method. The real-time FRET PCR method is based on a fluorescence melting curve analysis of a hybrid between an amplicon produced from the pOV-A6 specific sequence (Genbank accession no. S80278), a 162-bp repeated sequence specific to O. viverrini, and specific fluorophore-labeled probes. Mean melting temperature of O. viverrini DNA from the cercariae and each of two positive snails by shedding test was 66.3 ± 0.1. The O. viverrini infection rate in snails was 2.47% (2/81) by cercarial shedding test but was 8.52% (4/47) by real-time FRET PCR method. The real-time FRET PCR method is rapid and effective in examining a large number of snail samples simultaneously. Validation using molecular evidence from this procedure provides another tool for surveying the prevalence of O. viverrini-infected snails in Southeast Asian countries

Map to show the location of villages in which sampling took place.

<p>The locations of traditional villages are shown in red, resettlement villages in yellow.</p

Risk factors for anopheline mosquitoes caught in houses of traditional downstream villages.

<p>IRR = Incidence rate ratio. N is the number of households at each level.</p

Risk factors for putative vectors of Japanese encephalitis caught in houses.

<p>IRR = Incidence rate ratio. N is the number of households at each level.</p

Serological investigations of flavivirus prevalence in Khammouane Province, Lao People's Democratic Republic, 2007-2008.

International audienceA large-scale cross-sectional seroprevalence study of dengue (DEN) and Japanese encephalitis (JE) was conducted in Khammouane province, Lao PDR, as part of the initial baseline health impact assessment of the Nam Theun 2 hydroelectric dam construction project. Health surveys were performed between May 2007 and February 2008 with serum samples collected from healthy individuals involved in the resettlement program of 16 villages (total surveyed population 4,369). Hemagglutination inhibition assay using flavivirus antigens (DENV1, DENV3, and JEV) performed on 1,708 plasma specimens revealed 30.4% (519) cross-reactive positives, and 10% (172) and 1.3% (22) positives to JEV or DENV, respectively. Entomological surveys conducted during the rainy season of 2008 indicated the presence of competent flavivirus vectors (Culex vishnui group and Aedes albopictus), although Aedes aegypti was not found. Continued surveillance and investigation is warranted to assess the clinical disease burden of flaviviruses in this area that is undergoing rapid ecological and demographic change