Abstract
Pit latrines are the most common sanitation option in the developing world. They are simple to build but require periodic emptying which results in widespread dispersion of fecal pathogens in the environment. While much is known about the health risks of fecal-oral exposure, little is known about those resulting from the aerosolization of pathogens from fecal material. Bioaerosols were sampled around seven pit latrines before, after, and during emptying in Blantyre, Malawi. Bioaerosols were collected directly onto nutrient and selective medium agar plates using an impact sampler. DNA was extracted from some plates and analyzed for selected enteric pathogens. Total heterotrophic bacteria in the air during active emptying ranged from 198 to >13,000 colony forming units (CFU) per m3, and generally increased above background levels during pit emptying. At about one meter from the pit latrine emptying, E. coli and total coliforms concentrations in air reached up to 350 and 790 CFU m−3, respectively. Additionally, at four out of the seven pit latrines sites sampled, enterotoxigenic E. coli (ETEC) LT/ST was confirmed to be present in bioaerosols. This work demonstrates the potential for airborne dispersion of enteric pathogens during pit latrine emptying operations.
Highlights
On-site sanitation systems, such as pit latrines, are the most common sanitation option used throughout the developing world, and it is estimated that around 1.8 billion people use pit latrines as a main means of sanitation (Berendes et al, 2017; Graham and Polizzotto, 2013; Jenkins et al, 2015)
The rapid decrease of the bacteria levels after operations ceased would suggest that the most direct exposure risk may be to pit emptiers and by-standers, the transport and deposition of such bioaerosols is not well understood
Vacuum truck vent samples consistently exceeded our upper limit of detection for heterotrophic bacteria analysis, which varied between 5256 and 13,140 colony forming units (CFU) m−3 depending on air sample volume
Summary
Though simple to build and use, pit latrines and other onsite sanitation systems generally require periodic emptying, transport and treatment or disposal of the fecal sludge (Chunga et al, 2016; Mbéguéré et al, 2010; Sisco et al, 2015). It is generally accepted that the most common route of transmission for enteric pathogens is via the fecal-oral route (World Health Organization, 2004). No previous work has investigated the extent and content of bioaerosols generated during mechanized pit emptying practices.
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