Impact of ivermectin mass drug administration on burden of soil-transmitted helminths in onchocerciasis control and elimination programs, Yeki district, southwest Ethiopia

Abstract

Community-directed treatment with ivermectin (CDTi) is the primary strategy employed to control and eliminate human onchocerciasis in Ethiopia. After long-term mass distribution for onchocerciasis, ivermectin is expected to have additional benefits beyond the envisioned targets by reducing the burden of other co-endemic parasitic infections as to STHs. To date, studies focused on the collateral impact of CDTi on STH in Ethiopia are scanty. Two community-based cross-sectional surveys (baseline in 1997 and post-CDTi in 2017) were conducted to evaluate the impact of long-term CDTi employed to control and eliminate onchocerciasis on the burden of STH infections in Yeki district of southwest Ethiopia. Stool samples were collected and examined using Ritchie`s concentration and Kato-Katz techniques in the baseline and current study, respectively. Overall, 188(38.3%, 95% Confidence interval (CI) 34.1–42.7%) individuals were positive at least for any of the STH species from 491 study participants in the post-CDTi. The prevalence of A. lumbricoides, hookworms, and T. trichiura was 11.2% (95% CI 8.7–14.3%), 16.3% (95% CI 13.3–19.8%), and 29.9% (95% CI 26.1–34.1%), respectively. Individuals aged 5–9 years had a significantly higher prevalence of A. lumbricoides (Adjusted odds ratio (AOR) 6.5, 95% CI 1.7–25.4), T. trichuria (AOR 8, 95% CI 2.6–25.1), and any STH infection (AOR 5, 95% CI 1.7–14.7) than those of ≥ 51 years. Also, significantly higher prevalences of T. trichuria infection were observed in individuals aged 10–14 years (AOR 4.1, 95% CI 1.7–9.9), 15–20 years (AOR 3.1, 95% CI 1.2–8.1), 21–30 years (AOR 2.4, 95% CI 1.1–5.5), and 31–40 years (AOR 3.2, 95% CI 1.3–7.5) compared with those of ≥ 51 years. The prevalence of A. lumbricoides was significantly higher in males (AOR 0.5, 95% CI 0.3–0.9). Of the 491 study participants, only data from 400 individuals who had not been involved in a mass drug administration (MDA) with other STH anthelmintics were considered in the comparative analysis. Before CDTi, the prevalence of A. lumbricoides, T. trichiura, hookworm, and any STH infection was 47.1% (95% CI 41.6–52.7%), 3.3% (95% CI 1.8–5.9%), 37.9% (95% CI 32.7–43.5%), and 58.8% (95% CI 53.2–64.1%), respectively. Long-term CDTi considerably reduced the prevalences of A. lumbricoides and hookworm by 76.2% and 56.9%, respectively (p < 0.001). Nonetheless, CDTi did not affect the prevalence of T. trichiura infection and, in contrast, it was significantly higher in the current study (P < 0.001). Overall post-CDTi prevalence of any STH infection was considerably lower than reported in the baseline (p < 0.001). It is evidenced that long-term CDTi for onchocerciasis control and elimination had additional benefits by reducing the prevalence of STH infections specifically of A. lumbricoides and hookworm, but had no impact on infections with T. trichuria. Our finding of additional health benefits of large-scale ivermectin administration taking it will aid to increase positive engagement and sustain participation of communities during MDA campaigns, and strengthen governmental and non-governmental organizations (NGOs) support for the undergoing national onchocerciasis elimination program.

Community Based Interventions for the Prevention and Control of Soil-Transmitted Helminths in sub-Saharan Africa: A Systematic Review and Meta-analysis

“…Gebrezgabiher evaluated the impact of long-term CWT on STH infection with the drug ivermectin, primarily used to treat onchocerciasis. Prevalence of all STH infection significantly decreased from baseline to endline over the course of this multi-year study [32].…”

“…All other studies were consistent or did not report both prevalence and intensity. Three studies are excluded from the meta-analysis as enrolment numbers per treatment arm or baseline/endline are not provided [16,24,32]. This includes a cluster-RCT in Kenya assessing the impact of school-based WASH that only found a significant effect on A. lumbricoides prevalence and intensity, but not on T. trichiura or hookworm [16].…”

Effectiveness of ivermectin mass drug administration in the control of soil-transmitted helminth infections in endemic populations: a systematic review and meta-analysis

“…Lymphatic filariasis was the most commonly targeted primary disease, representing 64% of these studies ( n = 16) (19, 21, 22, 33, 35, 36, 38, 40–42, 44, 46). Ivermectin dosages were within standard range (one dose, 150–200 μg/kg) for most studies ( n = 18, 72%) where dosage was reported [ 17 – 22 , 24 , 25 , 34 – 37 , 40 – 44 ]. Two studies administered two doses given 7 to 14 days apart for scabies [ 17 , 42 ] while one study [ 44 ] used a higher dosage (400 μg/kg) for lymphatic filariasis.…”

“…Table 1 lists individual studies included in the systematic review with their characteristics while Table 2 provides an aggregated summary of the study characteristics. Of the 25 studies included in the systematic review, 17 (68%) used ivermectin and albendazole as their PC regimen [ 20 – 25 , 34 , 36 , 38 – 41 , 43 , 45 ] and 8 (32%) used ivermectin with no other anthelminthic drugs [ 17 – 19 , 35 , 37 , 42 , 44 ]. Nine studies used additional drugs in addition to ivermectin and/or albendazole [ 19 , 34 , 36 , 38 – 41 , 44 ].…”

“…The number of rounds of MDA administered between baseline and last prevalence assessment ranged between 1 and 23 rounds, with 10 (40%) studies administering only 1 round [ 17 , 19 , 22 – 24 , 41 , 42 , 44 , 45 ]. The follow-up time from last round ranged between 1 week and 36 months, with 16 (64%) studies being 12 months or less [ 17 – 20 , 22 , 23 , 25 , 35 , 37 – 40 , 43 , 44 ], 8 (32%) being between > 12 and ≤ 24 months [ 21 , 24 , 36 , 41 , 42 , 45 ], and 1 (4%) being greater than 24 months [ 34 ]. Of the 17 studies that assessed ivermectin and albendazole, there were between 1 and 16 rounds administered, with a median of 3 rounds.…”