Environmental determinants of E. coli, link with the diarrheal diseases, and indication of vulnerability criteria in tropical West Africa (Kapore, Burkina Faso)

Abstract

In 2017, diarrheal diseases were responsible for 606 024 deaths in Sub-Saharan Africa. This situation is due to domestic and recreational use of polluted surface waters, deficits in hygiene, access to healthcare and drinking water, and to weak environmental and health monitoring infrastructures. Escherichia coli (E. coli) is an indicator for the enteric pathogens that cause many diarrheal diseases. The links between E. coli, diarrheal diseases and environmental parameters have not received much attention in West Africa, and few studies have assessed health risks by taking into account hazards and socio-health vulnerabilities. This case study, carried out in Burkina Faso (Bagre Reservoir), aims at filling this knowledge gap by analyzing the environmental variables that play a role in the dynamics of E. coli, cases of diarrhea, and by identifying initial vulnerability criteria. A particular focus is given to satellite-derived parameters to assess whether remote sensing can provide a useful tool to assess the health hazard. Samples of surface water were routinely collected to measure E. coli, enterococci and suspended particulate matter (SPM) at a monitoring point (Kapore) during one year. In addition, satellite data were used to estimate precipitation, water level, Normalized Difference Vegetation Index (NDVI) and SPM. Monthly epidemiological data for cases of diarrhea from three health centers were also collected and compared with microbiological and environmental data. Finally, semi-structured interviews were carried out to document the use of water resources, contact with elements of the hydrographic network, health behavior and condition, and water and health policy and prevention, in order to identify the initial vulnerability criteria. A positive correlation between E. coli and enterococci in surface waters was found indicating that E. coli is an acceptable indicator of fecal contamination in this region. E. coli and diarrheal diseases were strongly correlated with monsoonal precipitation, in situ SPM, and Near Infra-Red (NIR) band between March and November. Partial least squares regression showed that E. coli concentration was strongly associated with precipitation, Sentinel-2 reflectance in the NIR and SPM, and that the cases of diarrhea were strongly associated with precipitation, NIR, E. coli, SPM, and to a lesser extent with NDVI. Moreover, E. coli dynamics were reproduced using satellite data alone, particularly from February to mid-December (R2 = 0.60) as were cases of diarrhea throughout the year (R2 = 0.76). This implies that satellite data could provide an important contribution to water quality monitoring. Finally, the vulnerability of the population was found to increase during the rainy season due to reduced accessibility to healthcare and drinking water sources and increased use of water of poor quality. During this period, surface water is used because it is close to habitations, easy to use and free from monetary or political constraints. This vulnerability is aggravated by marginality and particularly affects the Fulani, whose concessions are often close to surface water (river, lake) and far from health centers.

Effects of high temperature and heavy precipitation on drinking water quality and child hand contamination levels in rural kenya

“…In water sources, heavy rainfall increased E. coli levels, perhaps by transporting feces via increased runoff and flooding. This finding is consistent with studies in other locations 40,45,46 . The effect was larger after low 8-week rainfall, potentially because long dry periods allowed feces to accumulate in the environment.…”

“…This is supported by previous studies, which have observed increased diarrhea risk at heavy rainfall levels 37 . In previous diarrhea risk studies and recent water quality studies, temperature and precipitation have been examined at a variety of timescales (monthly, weekly, daily) 37,40,45,46 . We selected exposures at the weekly level for this analysis based on the assumption that E. coli survival would be highest at shorter time scales.…”

“…The copyright holder for this preprint this version posted October 5, 2022. ; https://doi.org/10.1101/2022.10.04.510863 doi: bioRxiv preprint 3 conditions, such as following prolonged dry periods 35,38,39 . Notably, of the 141 studies identified by Levy et al, only 11 (< 8%) were conducted in Sub-Saharan Africa 37,40 , suggesting a need for additional evidence in this geographic area.…”

“…Some studies have found that the association between rainfall and diarrhea only holds under certain 3 conditions, such as following prolonged dry periods 35,38,39 . Notably, of the 141 studies identified by Levy et al, only 11 (< 8%) were conducted in Sub-Saharan Africa 37,40 , suggesting a need for additional evidence in this geographic area.…”

“…High temperatures may influence pathogen survival in the environment, but the direction of the effect is unclear: pathogens may die off at a faster rate under high temperature conditions, but growth could also accelerate if sufficient nutrients are present 43,44 . A few recent studies found that heavy rainfall was associated with increased Escherichia coli (fecal indicator bacteria) levels in drinking water sources 40,[45][46][47] and household stored water 45,46 in locations in Bangladesh 46,47 , Burkina Faso 40 , Nepal 46 , and Tanzania 45,46 . Higher temperatures increased E. coli levels in Bangladesh and Nepal, but decreased E. coli levels in Tanzania 46 .…”