Effects of hydrological regime and land use on in-stream Escherichia coli concentration in the Mekong basin, Lao PDR.

In the basin of Mekong, over 70 million people rely on unimproved surface water for their domestic requirements. Surface water is often contaminated with fecal matter and yet little information exists on the underlying mechanisms of fecal contamination in tropical conditions at large watershed scales. Our objectives were to (1) investigate the seasonality of fecal contamination using Escherichia coli as fecal indicator bacteria (FIB), and (2) establish links between the fecal contamination in stream water and its controlling factors (hydrology and land use). We present the results of (1) a sampling campaign at the outlet of 19 catchments across Lao PDR, in both the dry and the rainy seasons of 2016, and (2) a 10-day interval monitoring conducted in 2017 and 2018 at three point locations of three rivers (Nam Ou, Nam Suang, and Mekong) in northern Lao PDR. Our results show the presence of fecal contamination at most of the sampled sites, with a seasonality characterized by higher and extreme E. coli concentrations occurring during the rainy season. The highest E. coli concentrations, strongly correlated with total suspended sediment concentrations, were measured in catchments dominated by unstocked forest areas, especially in mountainous northern Lao PDR and in Vientiane province.

Whole-Genome Assemblies of 16 Burkholderia pseudomallei Isolates from Rivers in Laos.

We report 16 Burkholderia pseudomallei genomes, including 5 new multilocus sequence types, isolated from rivers in Laos. The environmental bacterium B. pseudomallei causes melioidosis, a serious infectious disease in tropical and subtropical regions. The isolates are geographically clustered in one clade from around Vientiane, Laos, and one clade from further south.

Rivers as carriers and potential sentinels for Burkholderia pseudomallei in Laos.

Burkholderia pseudomallei, causative agent of the often fatal disease melioidosis, dwells in tropical soils and has been found in freshwater bodies. To investigate whether rivers are potential habitats or carriers for B. pseudomallei and to assess its geographical distribution in Laos, we studied 23 rivers including the Mekong, applying culture-based detection methods and PCR to water filters and streambed sediments. B. pseudomallei was present in 9% of the rivers in the dry season and in 57% in the rainy season. We found the pathogen exclusively in Southern and Central Laos, and mainly in turbid river water, while sediments were positive in 35% of the B. pseudomallei-positive sites. Our results provide evidence for a heterogeneous temporal and spatial distribution of B. pseudomallei in rivers in Laos with a clear north-south contrast. The seasonal dynamics and predominant occurrence of B. pseudomallei in particle-rich water suggest that this pathogen is washed out with eroded soil during periods of heavy rainfall and transported by rivers, while river sediments do not seem to be permanent habitats for B. pseudomallei. Rivers may thus be useful to assess the distribution and aquatic dispersal of B. pseudomallei and other environmental pathogens in their catchment area and beyond.

Risk perception of travelers to tropical and subtropical countries visiting a swiss travel health center.

BACKGROUND: This study assessed the risk perception ratings of travelers pre- and post-travel and in comparison to the ratings by travel health experts. While most surveys on travel health knowledge, attitudes, and practices focus on malaria and vaccine-preventable diseases, noninfectious travel risks were included in this study. METHODS: Pre- and post-travel perception of nine travel-associated health risks was recorded among 314 travelers to tropical and subtropical destinations. All travelers sought pre-travel health advice at the Travel Clinic of the Swiss Tropical and Public Health Institute in 2008 and 2009. In addition, 18 Swiss travel health experts provided an assessment of the respective risks. A validated visual psychometric measuring instrument was used [pictorial representation of illness and self measure (PRISM)]. RESULTS: Travelers and experts rated most risks similarly, except for accidents and sexually transmitted infections (STIs) which experts rated higher. Compared to other risks, accidents ranked highly in both groups and were the only risk perceived higher after travel. Pre- and post-travel perceptions of all other risks were similar with a tendency to be lower after travel. Travelers perceived mosquitoes to be the highest risk before travel and accidents after travel. CONCLUSION: Travelers' risk perception appears to be accurate for most risks stated in this study. However, travel health professionals should be aware that some perception patterns among travelers regarding travel-related health risks may be different from professional risk assessment. Important but insufficiently perceived health risks, such as sexual behavior/STIs and accidents, should be considered to be part of any pre-travel health advice package.