Exploring factors associated with Trichuris trichiura infection in school children in a high-transmission setting in Kenya

Abstract

Objectives: Kenya has implemented a national school-based deworming program, which has led to substantial decline in the prevalence of soil-transmitted helminths (STHs), although some pockets of infections remain. To effectively design an STH control program that leads to significant reductions of Trichuris trichiura, there is a need to understand the drivers of persistent infection despite ongoing treatment programs.

Methods: This study was conducted between July and September 2019 at the south coast of Kenya, using a two-stage sampling design. First, a school-based cross-sectional survey was conducted in 2265 randomly selected school children from selected schools in areas known to be endemic for T. trichiura. After this, we conducted a nested case-control study wherein all children positive for T. trichiura (142) were matched to 148 negative controls based on age and village. A household survey was then conducted with all household members of cases and controls. In addition, a subsample of 116 children found to be infected with T. trichiura were followed up to assess the efficacy of albendazole at day 21 post-treatment. The predictors of presence of T. trichiura were investigated through multilevel logistic regression, considering clustering of infection.

Results: Overall, 34.4% of the children were infected with at least one STH species; T. trichiura was the most common (28.3%), 89.1% of those with T. trichiura had light-intensity infections. The prevalence of T. trichiura was significantly higher in male children and was positively associated with younger age and number of people infected with T. trichiura in a household. The parasitological cure rate and egg reduction rate of T. trichiura were 35% and 51%, respectively. Other STHs identified were hookworm (9.6%) and Ascaris lumbricoides (5.7%).

Conclusions: T. trichiura remains a significant public health challenge in the study area with albendazole treatment efficacy against the parasite, remaining lower than the World Health Organization-recommended thresholds. Because of the observed focal transmission of T. trichiura in the current area, control efforts tailored to local conditions and targeting lower implementation units should be used to achieve optimal results on transmission.

Keywords: Albendazole; Efficacy; Kenya; Mass drug administration; Risk factors; School children; Soil-transmitted helminths; Trichuris trichiura.

Figure 1

Study flow diagram showing adherence in the screening survey conducted in school children in the 15 selected schools in Kwale county, Coastal Kenya.

Figure 2

(a) Age infection profiles for T. trichiura in 2265 school children in 15 schools in Kwale county, south coast. Prevalence (dark lines) and intensity (grey lines) males solid line and circles: females dashed lined and empty circles; 95% confidence intervals calculated considering school clusters. (b) School-specific prevalence of soil-transmitted helminth across fifteen school in Kwale county. (c) Age infection profiles for T. trichiura individuals in 4 villages in Kwale county, south coast. Prevalence (dark lines) and intensity (grey lines) males solid line and circles: females dashed lined and empty circles; 95% confidence intervals calculated considering village clusters. STHs, soil-transmitted helminths.

Figure 3

Infection intensities of individuals T. trichiura before and 21 days after treatment with albendazole. Three outliers >eggs per gram 1500 excluded.