Hydrological Regime and Water Shortage as Drivers of the Seasonal Incidence of Diarrheal Diseases in a Tropical Montane Environment

The global burden of diarrhea is a leading cause of morbidity and mortality worldwide. In montane areas of South-East Asia such as northern Laos, recent changes in land use have induced increased runoff, soil erosion and in-stream suspended sediment loads, and potential pathogen dissemination. To ou...

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Vydáno v:	PLoS neglected tropical diseases Ročník 10; číslo 12; s. e0005195
Hlavní autoři:	Boithias, Laurie, Choisy, Marc, Souliyaseng, Noy, Jourdren, Marine, Quet, Fabrice, Buisson, Yves, Thammahacksa, Chanthamousone, Silvera, Norbert, Latsachack, Keooudone, Sengtaheuanghoung, Oloth, Pierret, Alain, Rochelle-Newall, Emma, Becerra, Sylvia, Ribolzi, Olivier
Médium:	Journal Article
Jazyk:	angličtina
Vydáno:	United States Public Library of Science 01.12.2016 Public Library of Science (PLoS)
Témata:	Air temperature Analysis Anthropogenic factors Aquifers Bacteria Bans Catchment scale Climate effects Community Health Centers Creeks & streams Curie, Marie (1867-1934) Demography Diarrhea Diarrhea - epidemiology Diarrhea - microbiology Diarrhea - prevention & control Drinking water Drought E coli Earth Sciences Ecology and Environmental Sciences Epidemics Epidemiology Escherichia coli - isolation & purification Fecal coliforms Feces Feces - microbiology Female Groundwater discharge Groundwater levels Health risks Hospitals Human health and pathology Humans Hydrological research Hydrology Hygiene Land use Land use planning Laos - epidemiology Life Sciences Male Medicine and Health Sciences Montane environments open climate campaign Patient admissions People and Places Population density Rain Rainfall Retrospective Studies Risk factors River catchments River discharge River ecology River flow Rivers Rivers - microbiology Seasons Sediments Sociology Soil erosion Studies Surface water Suspended sediments Time series Tropical Climate Tropical diseases Variables Water Water Microbiology Water shortages Water Supply Water temperature Water wells Laos LAOS
ISSN:	1935-2735, 1935-2727, 1935-2735
On-line přístup:	Získat plný text
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Shrnutí:	The global burden of diarrhea is a leading cause of morbidity and mortality worldwide. In montane areas of South-East Asia such as northern Laos, recent changes in land use have induced increased runoff, soil erosion and in-stream suspended sediment loads, and potential pathogen dissemination. To our knowledge, few studies have related diarrhea incidences to catchment scale hydrological factors such as river discharge, and loads of suspended sediment and of Fecal Indicator Bacteria (FIB) such as Escherichia coli, together with sociological factors such as hygiene practices. We hypothesized that climate factors combined with human behavior control diarrhea incidence, either because higher rainfall, leading to higher stream discharges, suspended sediment loads and FIB counts, are associated with higher numbers of reported diarrhea cases during the rainy season, or because water shortage leads to the use of less safe water sources during the dry season. Using E. coli as a FIB, the objectives of this study were thus (1) to characterize the epidemiological dynamics of diarrhea in Northern Laos, and (2) to identify which hydro-meteorological and sociological risk factors were associated with diarrhea epidemics. Considering two unconnected river catchments of 22 and 7,448 km2, respectively, we conducted a retrospective time series analysis of meteorological variables (rainfall, air temperature), hydrological variables (discharge, suspended sediments, FIB counts, water temperature), and the number of diarrheal disease cases reported at 6 health centers located in the 5 southern districts of the Luang Prabang Province, Lao PDR. We also examined the socio-demographic factors potentially affecting vulnerability to the effect of the climate factors, such as drinking water sources, hygiene habits, and recreational water exposure. Using thus a mixed methods approach, we found E. coli to be present all year long (100-1,000 Most Probable Number or MPN 100 mL-1) indicating that fecal contamination is ubiquitous and constant. We found that populations switch their water supply from wells to surface water during drought periods, the latter of which appear to be at higher risk of bacterial contamination than municipal water fountains. We thus found that water shortage in the Luang Prabang area triggers diarrhea peaks during the dry and hot season and that rainfall and aquifer refill ends the epidemic during the wet season. The temporal trends of reported daily diarrhea cases were generally bimodal with hospital admissions peaking in February-March and later in May-July. Annual incidence rates were higher in more densely populated areas and mostly concerned the 0-4 age group and male patients. We found that anthropogenic drivers, such as hygiene practices, were at least as important as environmental drivers in determining the seasonal pattern of a diarrhea epidemic. For diarrheal disease risk monitoring, discharge or groundwater level can be considered as relevant proxies. These variables should be monitored in the framework of an early warning system provided that a tradeoff is found between the size of the monitored catchment and the frequency of the measurement.
Bibliografie:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23 Conceived and designed the experiments: MC FQ YB OS AP OR.Performed the experiments: NSo MJ CT NSi KL.Analyzed the data: LB MC MJ NSo.Wrote the paper: LB MC MJ ERN SB OR. The authors have declared that no competing interests exist.
ISSN:	1935-2735 1935-2727 1935-2735
DOI:	10.1371/journal.pntd.0005195