Results of a national school-based deworming programme on soil-transmitted helminths infections and schistosomiasis in Kenya: 2012-2017

Abstract

Background: Soil-transmitted helminth (STH) and schistosome infections are among the most prevalent neglected tropical diseases (NTDs) in the world. School-aged children are particularly vulnerable to these chronic infections that can impair growth, nutritional status and cognitive ability. Mass drug administration (MDA) delivered either once or twice annually is a safe and effective approach recommended by the World Health Organization (WHO) to reduce worm burden. In 2012, Kenya began a national school-based deworming programme (NSBDP) aimed at reducing infection and associated morbidity. The change in prevalence and intensity of these infections was monitored over five years (2012-2017). Here, we present the changes in STH and schistosome infections between baseline and endline assessments, as well as explore the yearly patterns of infection reductions.

Methods: We used series of pre- and post-MDA intervention, repeat cross-sectional surveys in a representative, stratified, two-stage sample of schools in 16 counties of Kenya. The programme consisted of two tiers of monitoring; a national baseline, midterm and endline surveys consisting of 200 schools, and pre- and post-MDA surveys conducted yearly consisting of 60 schools. Stool and urine samples were collected from randomly selected school children and examined for STH and schistosome infections using Kato-Katz and urine filtration techniques respectively.

Results: Overall, 32.3%, 16.4% and 13.5% of the children were infected with any STH species during baseline, midterm and endline assessment, respectively, with a relative reduction of 58.2% over the five-year period. The overall prevalence of S. mansoni was 2.1%, 1.5% and 1.7% and of S. haematobium was 14.8%, 6.8% and 2.4%, respectively, for baseline, midterm and endline surveys. We observed inter-region and inter-county heterogeneity variation in the infection levels.

Conclusions: The analysis provided robust assessment of the programme and outlined the current prevalence, mean intensity and re-infection pattern of these infections. Our findings will allow the Government of Kenya to make informed decisions on the strategy to control and eliminate these NTDs. Our results suggest that complimentary interventions may have to be introduced to sustain the chemotherapeutic gains of MDA and accelerate attainment of elimination of these NTDs as a public health problem in Kenya.

Keywords: Schistosomiasis; School-based deworming; Soil-transmitted helminths.

Fig. 1

Data collection time points for the M&E programme, 2012–2017

Fig. 2

The geographical distribution of STH infections prevalence at baseline (2012), midterm (2015) and endline (2017) among Kenyan school-aged children

Fig. 3

Trend in STH prevalence among Kenyan school-aged children, 2012–2017

Fig. 4

Mean intensity and prevalence of STH infections among Kenyan school-aged children

Fig. 5

The geographical distribution of S. mansoni infection prevalence at baseline (2012), midterm (2015) and endline (2017) among Kenyan school-aged children

Fig. 6

The geographical distribution of S. haematobium infections prevalence at baseline (2012), midterm (2015) and endline (2017) among Kenyan school-aged children

Fig. 7

Trend in schistosome infections prevalence among Kenyan school-aged children, 2012–2017

Fig. 8

STH treatment coverage (children), 2012–2017

Fig. 9

Schistosome treatment coverage (children), 2012–2017