Hands and Water as Vectors of Diarrheal Pathogens in Bagamoyo, Tanzania

Diarrheal disease is a leading cause of under-five childhood mortality worldwide, with at least half of these deaths occurring in sub-Saharan Africa. Transmission of diarrheal pathogens occurs through several exposure routes including drinking water and hands, but the relative importance of each route is not well understood. Using molecular methods, this study examines the relative importance of different exposure routes by measuring enteric bacteria (pathogenic <i>Escherichia coli</i>) and viruses (rotavirus, enterovirus, adenovirus) in hand rinses, stored water, and source waters in Bagamoyo, Tanzania. Viruses were most frequently found on hands, suggesting that hands are important vectors for viral illness. The occurrence of <i>E. coli</i> virulence genes (ECVG) was equivalent across all sample types, indicating that both water and hands are important for bacterial pathogen transmission. Fecal indicator bacteria and turbidity were good predictors of ECVG, whereas turbidity and human-specific <i>Bacteroidales</i> were good predictors of viruses. ECVG were more likely found in unimproved water sources, but both ECVG and viral genes were detected in improved water sources. ECVG were more likely found in stored water of households with unimproved sanitation facilities. The results provide insights into the distribution of pathogens in Tanzanian households and offer evidence that hand-washing and improved water management practices could alleviate viral and bacterial diarrhea

Prevalence of <i>E. coli</i> virulence genes (ECVG), enteric virus genes, human-specific <i>Bacteroidales</i> genes, and FIB detected in household stored drinking water and hand rinse samples of respondents with at least one child younger than five years old that were either sick with diarrhea (cases) versus matched healthy children under five years of age (controls).

<p>The study consisted of 112 unique case households (containing 113 case children) and 111 unique households with only healthy children (containing 113 matched, control children).</p><p>^a At least one of the seven pathogenic <i>E. coli</i> virulence genes (ECVG) measured present.</p><p>^b At least one of the three enteric viruses measured (rotavirus, adenovirus, enterovirus) present.</p><p>^c CI, confidence interval.</p><p>Presence/Absence of CFU per 2 hands; Presence/Absence or within specified range of CFU/100 mL stored drinking water with 0 CFU/100 mL as the reference group.</p><p>Indicates a median unbiased estimate.</p><p>Statistically significant (p≤0.05).</p

Binary logistic regression model of <i>E. coli</i> virulence genes (ECVG), enteric virus genes, and human-specific <i>Bacteroidales</i> genes presence in hand rinse samples as a function of hygiene behaviors.

<p>^a Ln-transformed.</p><p>^b Binary variables with values of 0 and 1.</p><p>^c Refers to the reported activity prior to the respondent having their hand rinse sample taken.</p><p>^d TZS Tanzanian Shillings.</p><p>N <306 because sample was lost or survey response not collected.</p><p>Statistically significant (p≤0.05).</p

Binary logistic regression model of <i>E. coli</i> virulence genes (ECVG), enteric virus genes, and human-specific <i>Bacteroidales</i> gene presence in household stored water as a function of water management behaviors.

<p>^a Ln-transformed.</p><p>^b Binary variables with values of 0 and 1.</p><p>^c Boiling, chlorinating, filtering, or SODIS (versus no treatment including settling).</p><p>^d Cup, mug, or bowl (versus pouring, long handled dipper, or spigot).</p><p>^e Borewell, rainwater, or tap (versus shallow well, cart/tanker, surface water, or vendor).</p><p>^f TZS Tanzanian Shillings.</p><p>N <306 because sample was lost or survey response not collected.</p><p>Statistically significant (p≤0.05).</p