Baseline investigation of (methyl)mercury in waters, soils, sediments and key foodstuffs in the Lower Mekong Basin : the rapidly developing city of Vientiane (Lao PDR)

We report here the first inventory of mercury (Hg) contamination in the ecosystem of Vientiane city, a representative emerging city bordering the Mekong River. Total Hg (THg) concentration in soil and sediments of both contrasting non-urbanized (wetland, rice paddy, Mekong River) and urbanized areas (wastewater canal and associated wastewater irrigated wetland) was low (8 to 101 ng g(-1)), reflecting the essentially non-industrialized status of the capital. Dissolved THg (2.2 +/- 2.2 ng l(-1)) and monomethyl-mercury (MMHg) concentrations (0.06 +/- 0.09 ng l(-1)) were also low in both surface and soil or sediment pore water with higher concentrations (up to 9 ng g(-1), THg and 0.53 ng g(-1) MMHg) measured in wetland and rice paddy suboxic waters. Dissolved organic carbon was identified as the main carrier in surface water for dissolved Hg transport towards the Mekong River. The measurement of low THg concentrations in rice (6.4 +/- 1.0 ng g(-1)) and fish (51 +/- 40 ng g(-1)) sampled in rice paddies and in the Mekong River confirmed the pristine state of the ecosystem of Vientiane area. Based on these data, we evaluated a low environmental Hg-attributable health risk for the local population whose diet relies on both fish and rice

Nasopharyngeal pneumococcal colonization density is associated with severe pneumonia in young children in the Lao People’s Democratic Republic

Background No studies have explored the association between pneumococcal nasopharyngeal density and severe pneumonia using the World Health Organization (WHO) 2013 definition. In Lao People’s Democratic Republic (Lao PDR), we determine the association between nasopharyngeal pneumococcal density and severe pneumonia in children. Methods A prospective observational study was undertaken at Mahosot Hospital, Vientiane, from 2014 to mid-2018. Children <5 years admitted with acute respiratory infections (ARIs) were included. Clinical and demographic data were collected alongside nasopharyngeal swabs for pneumococcal quantification by lytA real-time quantitative polymerase chain reaction. Severe pneumonia was defined using the 2013 WHO definition. For pneumococcal carriers, a logistic regression model examined the association between pneumococcal density and severe pneumonia, after adjusting for potential confounders including demographic and household factors, 13-valent pneumococcal conjugate vaccine status, respiratory syncytial virus co-detection, and preadmission antibiotics. Results Of 1268 participants with ARI, 32.3% (n = 410) had severe pneumonia and 36.9% (n = 468) had pneumococcal carriage. For pneumococcal carriers, pneumococcal density was positively associated with severe pneumonia (adjusted odds ratio, 1.4 [95% confidence interval, 1.1–1.8]; P = .020). Conclusions Among children with ARIs and pneumococcal carriage, pneumococcal carriage density was positively associated with severe pneumonia in Lao PDR. Further studies may determine if pneumococcal density is a useful marker for pneumococcal conjugate vaccine impact on childhood pneumonia