Posted: February 23, 2018

STH by the numbers: Mixed progress on preventive chemotherapy coverage among all children at risk of STH

Note: This article was updated on March 13, 2018 to reflect revised global coverage figures

The World Health Organization (WHO) recommends countries with ≥20% prevalence of soil-transmitted helminthiasis (STH) at baseline administer preventive chemotherapy (PC) to preschool-age (PSAC: ages 1-4) and school-age children (SAC: ages 5-14). The related WHO target is ≥75% treatment coverage of PSAC and SAC in all countries requiring preventive chemotherapy (PC) by 2020. Ministries of health annually report PC coverage by risk group[i] to monitor progress toward the indicated target. Using publicly available WHO data, we analyzed progress in PC coverage among all children in countries requiring PC. The analysis considers any country reporting zero treatments or lacking reported data as not having conducted PC.

From 2006 to 2016, countries requiring PC for STH decreased from 130 to 103 (-21%),[1] while global treatment coverage[2] for all children increased from 15% to 60% (Figure 1). In 2016, over 500 million children requiring PC received PC, an 18% increase from 2015. Of countries requiring PC in 2016, 50 (49%) treated PSAC and SAC (Table 1). Of countries requiring PC in 2016, 50 (49%) treated PSAC and SAC (Table 1). This is the highest proportion of countries treating both risk groups in a given year. However, the number of countries treating both risk groups has largely remained the same from 2006 (47) to 2016 (50). Data from the last three years bear this out; of 53 countries not providing PC to both risk groups in 2016, 38 (72%) also did not provide PC to both risk groups in 2014 or 2015.

In 2016, 20 (19%) countries treated only SAC and five (5%) only treated PSAC. Of these 25 countries, only 9 (36%) reached 75% PC coverage among all children. More than half of the countries treating both risk groups reached the 75% coverage target for all children in 2016. Considering all countries (N=103), regardless of which risk group(s) they treated, 35 (34%) reached the ≥75% PC coverage target for all children in 2016 (Figure 2). With the 2020 target quickly approaching, the failure to meet the coverage target in the majority of countries is obviously concerning. And while most countries (73%) conducted PC for at least one risk group in 2016, a marked 165 million (20%) children requiring PC live in countries not conducting any PC or in countries where their risk group did not receive PC.

Globally, PC coverage rates have increased substantially as have the number of children treated. The WHO strategy of focusing on countries with large numbers of at-risk children [3] has been a key contributing factor to increased coverage. However, achievement of the WHO coverage target by 2020 is uncertain given, among other factors, the lack of treatment of both risk groups in most countries. It would be difficult to argue that a country unable to cover both risk groups – which share similar levels of risk – implements effective STH control programming. Partners should prioritize technical and financial support toward those countries that have been consistently unable to treat PSAC and SAC. Quantifying the exact impact of inconsistent PSAC and SAC treatment across years is not possible, given available data, but it is reasonable to assume that inconsistent targeting undermines progress. Failure to treat both risk groups leaves a large reservoir of infection negatively impacting the entire community. Finally, missing the target will mean millions of at-risk children go unreached, undermining achievement of the WHO goal of eliminating moderate-to-high intensity infections in all children.

*Inclusion of information in STH by the Numbers does not constitute “publication” of that information.

[1]World Health Organization. PCT Databank

[2]Data source for number of countries requiring preventive chemotherapy by year: World Health Organization. Weekly Epidemiological Record

[3]Data source for preventive chemotherapy coverage: WHO PCT Databank. Accessed January 19, 2018 and available at