Effect of deworming on physical fitness of school-aged children in Yunnan, China: a double-blind, randomized, placebo-controlled trial

Abstract

Background: There is considerable debate on the health impacts of soil-transmitted helminth infections. We assessed effects of deworming on physical fitness and strength of children in an area in Yunnan, People's Republic of China, where soil-transmitted helminthiasis is highly endemic.

Methodology: The double-blind, randomized, placebo-controlled trial was conducted between October 2011 and May 2012. Children, aged 9-12 years, were treated with either triple-dose albendazole or placebo, and monitored for 6 months post-treatment. The Kato-Katz and Baermann techniques were used for the diagnosis of soil-transmitted helminth infections. Physical fitness was assessed with a 20-m shuttle run test, where the maximum aerobic capacity within 1 min of exhaustive exercise (VO2 max estimate) and the number of 20-m laps completed were recorded. Physical strength was determined with grip strength and standing broad jump tests. Body height and weight, the sum of skinfolds, and hemoglobin levels were recorded as secondary outcomes.

Principal findings: Children receiving triple-dose albendazole scored slightly higher in the primary and secondary outcomes than placebo recipients, but the difference lacked statistical significance. Trichuris trichiura-infected children had 1.6 ml kg(-1) min(-1) (P = 0.02) less increase in their VO2 max estimate and completed 4.6 (P = 0.04) fewer 20-m laps than at baseline compared to non-infected peers. Similar trends were detected in the VO2 max estimate and grip strength of children infected with hookworm and Ascaris lumbricoides, respectively. In addition, the increase in the VO2 max estimate from baseline was consistently higher in children with low-intensity T. trichiura and hookworm infections than in their peers with high-intensity infections of all soil-transmitted helminths (range: 1.9-2.1 ml kg(-1) min(-1); all P<0.05).

Conclusions/significance: We found no strong evidence for significant improvements in physical fitness and anthropometric indicators due to deworming over a 6-month follow-up period. However, the negative effect of T. trichiura infections on physical fitness warrants further investigation.

Figure 1. Profile of randomized controlled trial conducted in south-west Yunnan province, P.R. China, from October 2011 to May 2012.

Figure 2. Three-dimensional visualization of changes in 20-m laps due to differences in soil-transmitted helminth infection intensities in Chinese children.

The study was carried out in south-west Yunnan province, P.R. China between October 2011 and May 2012 among 194 children aged 9–12 years. The changes in infection intensities between the 4-month follow-up and baseline for Ascaris lumbricoides, Trichuris trichiura, and hookworm are reflected along the X-, Y-, and Z-axis, respectively. Each circle indicates the change for a particular child harboring a certain mixture of soil-transmitted helminth infection intensities. Blue circles indicate positive change, red circles indicate negative change, and white circles indicate no change. A darker shade of color indicates a greater degree of change.

Figure 3. Boxplots of six infection intensity groups identified by principal component and cluster analysis.

The groups are based on infection intensities of the three soil-transmitted helminths at baseline (white), 1-month follow-up (light grey), and 4-month follow-up (dark grey), among 194 children from a randomized controlled trial conducted in south-west Yunnan province, P.R. China, from October 2011 to May 2012.