Fig 1.
The different steps of the optimized straining-flotation method to detect and quantify STH eggs/larvae in soil.
The optimized straining-flotation method consists of 9 consecutive steps, including the homogenization of the soil sample (step 1), sieving of the sample (step 2), the transfer of the sieved soil into a 50 mL tube (step 3), centrifugation of this test tube at 2,000 g for 5 min (step 4), discard supernatant, add water to bring the pellet to suspension, equally divide suspension over two 15 mL tubes, and repeat the centrifugation step (step 5), discard supernatants and add flotation solution to each of the test tubes (step 6), centrifuge the tubes at 2,000 g for 2 min (step 7) and put the supernatants over a PuriStrainer sieve (step 8), transfer the material from the PuriStrainer sieve to a microscopic slide or in a 2 mL tube for microscopic or molecular analysis, respectively (step 9).
Fig 2.
The recovery rate of Ascaris and Trichuris eggs following serial flotation.
The spaghetti plots illustrate the cumulative egg recovery rate when serial flotation was applied. The color code differentiates the time at which the first coverslip was removed from the flotation tube.
Table 1.
The egg recovery rate for Ascaris and Trichuris across five experiments.
The p-values were based on a non-parametric test (Wilcoxon rank sum test).
Fig 3.
The diagnostic performance of the optimized straining-flotation method to detect and quantify Ascaris and Trichuris eggs in soil.
The panels describe the sensitivity for both microscopy and qPCR (top row panels), the egg recovery rate for microscopy (middle row panels) and the Ct-values for qPCR (bottom row panels) separately for Ascaris (left column panels) and Trichuris (right column panels).
Fig 4.
The environmental STH contamination at 10 school compounds, Jimma Town (Ethiopia).
This figure illustrates the environmental soil-transmitted helminth contamination across 10 governmental schools in Jimma Town, Ethiopia (Panel A), at different sites within schools (classroom, latrine and playground; Panel B), around different places around the school latrine (Panel C), and the association between prevalence of STH infections in children and the proportion of the samples contaminated with STH at the school level (Panel D).
Fig 5.
The environmental contamination with human STHs at the households and open markets.
This figure illustrates the environmental soil-transmitted helminth contamination across 50 households (Panels A and B) and 9 open markets (Panels C and D).
Table 2.
The characteristics and the corresponding environmental contamination of 50 households in Jimma Town, Ethiopia.
The environmental contamination measured by the mean soil-transmitted helminth egg counts across the samples. The p-value was based on the Wilcoxon rank sum test in case of two-level variables, while in case of variables with more than two levels it was based on the Kruskall Wallis test.