Trichuris trichiura infection and its relation to environmental factors in Mbeya region, Tanzania: A cross-sectional, population-based study

Abstract

BackgroundThe intestinal nematode Trichuris trichiura is among the most common causes of human infectious disease worldwide. As for other soil-transmitted nematodes, its reproductive success and thus prevalence and intensity of infection in a given area strongly depend on environmental conditions. Characterization of the influence of environmental factors can therefore aid to identify infection hot spots for targeted mass treatment.MethodologyWe analyzed data from a cross-sectional survey including 6234 participants from nine distinct study sites in Mbeya region, Tanzania. A geographic information system was used to combine remotely sensed and individual data, which were analyzed using uni- and multivariable Poisson regression. Household clustering was accounted for and when necessary, fractional polynomials were used to capture non-linear relationships between T. trichiura infection prevalence and environmental variables.Principal findingsT. trichiura infection was restricted to the Kyela site, close to Lake Nyasa with only very few cases in the other eight sites. The prevalence of T. trichiura infection in Kyela was 26.6% (95% confidence interval (CI) 23.9 to 29.6%). Multivariable models revealed a positive association of infection with denser vegetation (prevalence ratio (PR) per 0.1 EVI units = 2.12, CI 1.28 to 3.50) and inverse associations with rainfall (PR per 100 mm = 0.54, CI 0.44 to 0.67) and elevation (PR per meter = 0.89, CI 0.86 to 0.93) while adjusting for age and previous worm treatment. Slope of the terrain was modelled non-linearly and also showed a positive association with T. trichiura infection (p-value p<0.001).Conclusion/SignificanceHigher prevalences of T. trichiura infection were only found in Kyela, a study site characterized by denser vegetation, high rainfall, low elevation and flat terrain. But even within this site, we found significant influences of vegetation density, rainfall, elevation and slope on T. trichiura infection. The inverse association of rainfall with infection in Kyela is likely due to the fact, that rainfall in this site is beyond the optimum conditions for egg development. Our findings demonstrate that use of remotely sensed environmental data can aid to predict high-risk areas for targeted helminth control.

Prevalence of intestinal parasites and the absence of soil-transmitted helminths in Añatuya, Santiago del Estero, Argentina

“…Most intestinal parasites have a cosmopolitan distribution and are present in both rural and peri-urban areas, especially those that are acquired via waterborne transmission or through direct contact [39]. Other intestinal parasites, such as STH, are more prevalent in tropical and sub-tropical areas of the world, probably due to their need of passage through the soil, making them more sensitive to the external environment [12, 40, 41]. Living conditions are also associated with the presence of intestinal parasites, including STH, since they are excreted in the faeces and therefore the lack of improved sanitation and access to clean water are key factors [1, 9, 13].…”

Schistosoma haematobium infection and environmental factors in Southwestern Tanzania: A cross-sectional, population-based study

“…Fig 2 provides an overview of the study area, the study sites and the participating households. Below we briefly describe the study area and data collection methods, more detailed accounts and results for other helminth infections in this population are provided elsewhere [ 21 – 23 ].…”

Archaeoparasitology of Korean Mummies

“…Trichuris trichiura: This species currently infects 800 million people globally (Manz et al 2017). The earliest aDNA analysis for T. trichiura was performed on an SSU rRNA sequence isolated in mid-eighteenth century human remains of the Joseon period (Oh et al 2010).…”