Mass Administration of Ivermectin for the Elimination of Onchocerciasis Significantly Reduced and Maintained Low the Prevalence of <i>Strongyloides stercoralis</i> in Esmeraldas, Ecuador

<div><p>Objectives</p><p>To evaluate the effect of ivermectin mass drug administration on strongyloidiasis and other soil transmitted helminthiases.</p><p>Methods</p><p>We conducted a retrospective analysis of data collected in Esmeraldas (Ecuador) during surveys conducted in areas where ivermectin was annually administered to the entire population for the control of onchocerciasis.</p><p>Data from 5 surveys, conducted between 1990 (before the start of the distribution of ivermectin) and 2013 (six years after the interruption of the intervention) were analyzed. The surveys also comprised areas where ivermectin was not distributed because onchocerciasis was not endemic.</p><p>Different laboratory techniques were used in the different surveys (direct fecal smear, formol-ether concentration, IFAT and IVD ELISA for <i>Strongyloides stercoralis</i>).</p><p>Results</p><p>In the areas where ivermectin was distributed the strongyloidiasis prevalence fell from 6.8% in 1990 to zero in 1996 and 1999. In 2013 prevalence in children was zero with stool examination and 1.3% with serology, in adult 0.7% and 2.7%.</p><p>In areas not covered by ivermectin distribution the prevalence was 23.5% and 16.1% in 1996 and 1999, respectively. In 2013 the prevalence was 0.6% with fecal exam and 9.3% with serology in children and 2.3% and 17.9% in adults.</p><p>Regarding other soil transmitted helminthiases: in areas where ivermectin was distributed the prevalence of <i>T</i>. <i>trichiura</i> was significantly reduced, while <i>A</i>. <i>lumbricoides</i> and hookworms were seemingly unaffected.</p><p>Conclusions</p><p>Periodic mass distribution of ivermectin had a significant impact on the prevalence of strongyloidiasis, less on trichuriasis and apparently no effect on ascariasis and hookworm infections.</p></div

1996–Prevalence of anti–<i>S</i>. <i>stercoralis</i> antibodies (IFAT), Non-oncho-areas (200 children 5–17 y).

<p>1996–Prevalence of anti–<i>S</i>. <i>stercoralis</i> antibodies (IFAT), Non-oncho-areas (200 children 5–17 y).</p

Year 2013: Classification of Ss infection according to the combined result of fecal examination plus serology, by area and age group.

<p>Year 2013: Classification of Ss infection according to the combined result of fecal examination plus serology, by area and age group.</p

Map indicating the areas submitted and not submitted to ivermectin MDA for onchocerciasis (Oncho-areas and Non-oncho-areas, respectively).

<p>Map indicating the areas submitted and not submitted to ivermectin MDA for onchocerciasis (Oncho-areas and Non-oncho-areas, respectively).</p

Children (5–17 years), 1996, Oncho-areas versus Non-oncho-areas (formol–ether concentration).

<p>Children (5–17 years), 1996, Oncho-areas versus Non-oncho-areas (formol–ether concentration).</p

Adults, 1990 (direct stool examination) vs 1996 (formol—ether concentration) in Oncho-areas.

<p>Adults, 1990 (direct stool examination) vs 1996 (formol—ether concentration) in Oncho-areas.</p

Year 2013 (formol–ether concentration): Children and adults.

<p>Year 2013 (formol–ether concentration): Children and adults.</p

Timeline of the prevalence surveys and of ivermectin mass administration.

<p>Timeline of the prevalence surveys and of ivermectin mass administration.</p

Year 1999 (formol—ether concentration), children 1–17 y.

<p>Year 1999 (formol—ether concentration), children 1–17 y.</p