Soil-Transmitted Helminths in Southwestern China: A Cross-Sectional Study of Links to Cognitive Ability, Nutrition, and School Performance among Children.

Chengfang Liu,Shaoping Li,Linxiu Zhang,Alexis Medina,Jujun Wang,Guofei Wang,Yunli Bai,Renfu Luo,Scott Smith,Scott Rozelle,Hongmei Yi,Darren J Gray

doi:10.1371/journal.pntd.0003877

Abstract

BackgroundEmpirical evidence suggests that the prevalence of soil-transmitted helminth (STH) infections in remote and poor rural areas is still high among children, the most vulnerable to infection. There is concern that STH infections may detrimentally affect children’s healthy development, including their cognitive ability, nutritional status, and school performance. Medical studies have not yet identified the exact nature of the impact STH infections have on children. The objective of this study is to examine the relationship between STH infections and developmental outcomes among a primary school-aged population in rural China.Methodology/Principal FindingsWe conducted a large-scale survey in Guizhou province in southwest China in May 2013. A total of 2,179 children aged 9-11 years living in seven nationally-designated poverty counties in rural China served as our study sample. Overall, 42 percent of the sample’s elementary school-aged children were infected with one or more of the three types of STH—Ascaris lumbricoides (ascaris), Trichuris trichuria (whipworm) and the hookworms Ancylostoma duodenale or Necator americanus. After controlling for socioeconomic status, we observed that infection with one or more STHs is associated with worse cognitive ability, worse nutritional status, and worse school performance than no infection. This study also presents evidence that children with Trichuris infection, either infection with Trichuris only or co-infected with Trichuris and Ascaris, experience worse cognitive, nutritional and schooling outcomes than their uninfected peers or children infected with only Ascaris.Conclusions/SignificanceWe find that STH infection still poses a significant health challenge among children living in poor, rural, ethnic areas of southwest China. Given the important linkages we find between STH infection and a number of important child health and educational outcomes, we believe that our results will contribute positively to the debate surrounding the recent Cochrane report.

Highlights

A recent Cochrane Report [1] has raised questions about the nature of the relationship between infection with soil-transmitted helminths (STHs) and children’s healthy development
Empirical evidence suggests that the prevalence of soil-transmitted helminth (STH) infections in remote and poor rural areas is still high among children, the most vulnerable to infection
Medical studies have not yet identified the exact nature of the impact STH infections have on children

Summary

Introduction

A recent Cochrane Report [1] has raised questions about the nature of the relationship between infection with soil-transmitted helminths (STHs) and children’s healthy development. The report ended with a call for more concerted research that would help clarify the nature of the relationship between STH infection and these outcomes in children. Empirical evidence suggests that the prevalence of soil-transmitted helminth (STH) infections in remote and poor rural areas is still high among children, the most vulnerable to infection. There is concern that STH infections may detrimentally affect children’s healthy development, including their cognitive ability, nutritional status, and school performance.

Objectives

Methods

Results

Discussion

Conclusion