Schistosomiasis and Soil Transmitted Helminths Distribution in Benin: A Baseline Prevalence Survey in 30 Districts

<div><p>In 2013, Benin developed strategies to control neglected tropical diseases and one of the first step was the disease mapping of the entire country in order to identify endemic districts of schistosomiasis and soil transmitted helminths (STH). This study was carried out in 30 of the 77 districts of Benin. Of these 30 districts 22 were previously treated for Lymphatic Filariasis (LF) using the Ivermectin and Albendazole combination. In each district, five schools were selected and 50 children aged 8 to 14 years were sampled in each school, making a total of 250 children sampled in the district. The schools were selected mainly according to their proximity to lakes or any bodies of water that were likely to have been used by the children. Samples of faeces and urine were collected from each pupil. Urinary schistosomiasis was identified using the urine filtration technique while STH and intestinal schistosomiasis were identified through the Kato Katz method. Overall a total of 7500 pupils were surveyed across 150 schools with a gender ratio of 1:1. Hookworm was identified in all 30 districts with a prevalence ranging from 1.2% (95%CI: 0.0–2.5) to 60% (95%CI: 53.9–66.1). <i>Ascaris lumbricoides</i> was detected in 19 districts with a prevalence rate between 1% (95%CI: 0.0–2.2) and 39% (95%CI: 32.9–45.0). In addition to these common STH, <i>Trichuris trichiura</i>, <i>Enterobius vermicularis</i> and <i>Strongyloides stercoralis</i> were found at low prevalence. Only 16 districts were endemic to <i>Schistosoma mansoni</i>, while 29 districts were endemic to <i>S</i>. <i>haematobium</i>. The <i>S</i>. <i>haematobium</i> prevalence ranged from 0.8% (95% CI: 0.0–1.9) to 56% (95% CI: 50.2–62.5) while the prevalence of <i>S</i>. <i>mansoni</i> varied from 0.4% (95%CI: 0.0–1.2) to 46% (95% CI: 39.8–52.2). The 22 districts, where LF was successfully eliminated, still require mass drug administration (MDA) of albendazole indicating that school-based MDA would be needed even after LF elimination in districts co-endemic to LF and STH in Benin.</p></div

Comparison of the average prevalence of <i>S</i>. <i>haematobium</i> in each department.

<p>Comparison of the average prevalence of <i>S</i>. <i>haematobium</i> in each department.</p

Intensity of urinary and intestinal schistosomiasis infection in districts surveyed.

<p>N: Number of positive samples out the total (250) examined in each commune. For <i>S</i>. <i>haematobium</i> intensity Light: 1–50 eggs/10ml of urine; High: ≥ 50 eggs/10ml of urine For <i>S</i>. <i>mansoni</i> intensity Light: 1-99EPG; Moderate: 100–399 EPG; High: ≥ 400EPG.</p

Comparison of the average prevalence of Hookworm in each department.

<p>On the chart, the department sharing similar letter are not significantly different. Those sharing different letters indicate a significant difference [p<0.0001]</p

Comparison of the prevalence of the most common STH (Hookworm) to <i>S</i>.<i>haematobium</i>.

<p><b>X2: Chi-square value of comparison of Hookworm and S. haematobium prevalence within each district. p-value: p value of comparison of Hookworm and S. haematobium prevalence within each district.</b> In each column, the letter “a”, “b” or “c” indicates that the prevalence sharing similar letter are not significantly different while those sharing different letters are significantly different.</p

Comparison of the average prevalence of <i>S</i>. <i>mansoni</i> in each department.

<p>Comparison of the average prevalence of <i>S</i>. <i>mansoni</i> in each department.</p

Comparison of the average prevalence of <i>A</i>. <i>lumbricoides</i> in each department.

<p>Comparison of the average prevalence of <i>A</i>. <i>lumbricoides</i> in each department.</p

Prevalence rate and intensity of other soil transmitted helminths found in the 30 districts mapped in 2014 in Benin.

<p>N: Total number of positive samples out the total (250) examined in each commune, 95%CI: 95% confidence interval for prevalence. For <i>E</i>. <i>vermicularis</i> and <i>T</i>. <i>trichiura intensity</i>: Light: 1-999EPG; Moderate: 1000-9999EPG; High: ≥10000EPG. For S. <i>stercoralis</i> Light: 1-800EPG; Moderate: 801-1200EPG; High: >1200EPG.</p

Intensity of Hookworm and <i>A</i>. <i>lumbricoides</i> infections in districts surveyed.

<p>N: Number of positive sampled out the total (250) examined in each commune. For Hookworm intensity, Light: 1-1999EPG; Moderate: 2000-3999EPG; High: ≥4000EPG. For <i>A</i>. <i>lumbricoides</i> intensity, Light: 1-4999EPG; Moderate: 5000-49999EPG; High: ≥50000EPG.</p

Prevalence of the most common soil transmitted helminths and schistosomiasis found in 30 districts in Benin.

<p>In each column, the letter “a”, “b” or “c” indicates that the prevalence sharing similar letter are not significantly different while those sharing different letters are significantly different [p<0.0001]. <b>N: Total number sampled, 95%CI: 95% confidence interval for prevalence.</b></p