National mapping of soil-transmitted helminth and schistosome infections in Ethiopia

Abstract

Background: An accurate understanding of the geographical distributions of both soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, and the hookworms Necator americanus and Ancylostoma duodenale) and schistosomes (SCH; Schistosoma mansoni and S. haematobium) is pivotal to be able to effectively design and implement mass drug administration (MDA) programmes. The objective of this study was to provide up-to-date data on the distribution of both STH and SCH in Ethiopia to inform the design of the national control program and to be able to efficiently achieve the 75% MDA coverage target set by the WHO.

Methods: Between 2013 and 2015, we assessed the distributions of STH and SCH infections in a nationwide survey covering 153,238 school-aged children (aged 5-15 years), from 625 woredas (districts), representing all nine Regional States and two City Administrations of Ethiopia. Nationwide disease maps were developed at the woreda level to enable recommendations on the design of the national MDA programme.

Results: The prevalence of any STH infection across the study population was 21.7%, with A. lumbricoides (12.8%) being the most prevalent STH, followed by hookworms (7.6%) and T. trichiura (5.9%). The prevalence for any SCH was 4.0% in areas where both SCH species were evaluated. Schistosoma mansoni was the most prevalent SCH (3.5 vs 0.3%). STHs were more prevalent in southwest Ethiopia, whereas SCH was found mostly in the west and northeast of the country. The prevalence of moderate-to-heavy intensity infections was 2.0% for STHs and 1.6% for SCH. For STH, a total of 251 woredas were classified as moderately (n = 178) or highly endemic (n = 73), and therefore qualify for an annual and biannual MDA program, respectively. For SCH, 67 woredas were classified as endemic and 8 as highly endemic, and hence they require every two years and annual MDA programme, respectively.

Conclusions: The results confirm that Ethiopia is endemic for both STHs and SCH, posing a significant public health problem. Following the WHO recommendations on mass drug administration, 18 and 14 million school-aged children are in need of MDA for STHs and SCH, respectively, based on the number of SACs that live on the eligible geographical areas.

Keywords: Ascaris; Disease maps; Endemicity; Mass drug administration; Schistosoma haematobium; Schistosoma mansoni; Schistosomiasis; School-aged children; Soil-transmitted helminthiasis; Trichuris; Woreda (districts); hookworms.

Fig. 1

The woreda prevalence of any soil-transmitted helminth infections in school-aged children, Ethiopia 2013–2015. The map illustrates the woreda-level prevalence of any soil-transmitted helminth infections in 153,238 school-aged children, Ethiopia 2013–2015. The woreda-level prevalence is based on the number of children, which were found to be positive based on single Kato-Katz thick smear, over the total number of children screened in a woreda. The source of the administrative boundaries is www.gadm.org/

Fig. 2

The woreda prevalence of moderate-to-heavy intensity soil-transmitted helminth infections in school-aged children, Ethiopia 2013–2015. The maps illustrate the woreda-level prevalence of moderate-to-heavy intensity (MHI) infections for Ascaris lumbricoides (a), Trichuris trichiura (b) and hookworm (c) in 153,238 school-aged children, Ethiopia 2013–2015. The woreda prevalence is based on the number of MHI infections over the total number of children screened in a woreda. The classification of MHI infections are based on the World Health Organization criteria [4]. The source of the administrative boundaries is www.gadm.org/

Fig. 3

Woreda prevalence of Schistosoma mansoni and S. haematobium in school-aged children, Ethiopia 2013–2015. The maps illustrate the woreda prevalence of S. mansoni (a) and S. haematobium infections (b) in 153,238 (S. mansoni) and 112,217 (S. haematobium) school-aged children, Ethiopia 2013–2015. The woreda prevalence is based on the number of infections over the total number of children screened in a woreda. The source of the administrative boundaries is www.gadm.org/

Fig. 4

The woreda prevalence of moderate-to-heavy intensity schistsome infections in school-aged children, Ethiopia 2013–2015. The maps illustrate the woreada prevalence of moderate-to-heavy intensity S. mansoni (a) and S. haematobium infections (b) in 153,238 (S. mansoni) and 112,217 (S. haematobium) school-aged children, Ethiopia 2013–2015. The woreda prevalence is based on the number of MHI infections over the total number of children screened in a woreda. The classification of MHI infections are based on the World Health Organization criteria [4]. The source of the administrative boundaries is www.gadm.org/