Effect of Deworming on Indices of Health, Cognition, and Education Among Schoolchildren in Rural China: A Cluster-Randomized Controlled Trial

Chengfang Liu China Center for Agricultural Policy, School of Advanced Agricultural Sciences, Peking University, Beijing, China.

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Louise Lu Yale University School of Medicine, New Haven, Connecticut.
Freeman Spogli Institute, Stanford University, Stanford, California.

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Linxiu Zhang Center for Chinese Agricultural Policy, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.

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Renfu Luo China Center for Agricultural Policy, School of Advanced Agricultural Sciences, Peking University, Beijing, China.

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Sean Sylvia School of Economics, Renmin University of China, Beijing, China.

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Alexis Medina Freeman Spogli Institute, Stanford University, Stanford, California.

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Scott Rozelle Freeman Spogli Institute, Stanford University, Stanford, California.

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Darvin Scott Smith Stanford University School of Medicine, Stanford, California.

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Yingdan Chen National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China.

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Tingjun Zhu National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China.

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Soil-transmitted helminths (STHs) infect over one billion people worldwide. There is concern that chronic infection with STHs among school-aged children may detrimentally affect their development, including their health, cognition, and education. However, two recent Cochrane reviews examining the impact of deworming drugs for STH on nutrition, hemoglobin, and school performance found that randomized controlled trials (RCTs) in the literature provide an insufficient evidence base to draw reliable conclusions. This study uses a cluster-RCT to add to existing evidence by assessing the impact of a deworming intervention on nutrition, cognition, and school performance among schoolchildren in rural China. The intervention, implemented by local health practitioners in a setting with a baseline infection prevalence of 41.9% (95% confidence interval [CI] = 39.8%, 43.9%) and infection intensity of 599.5 eggs per gram of feces among positive-tested schoolchildren (95% CI = 473.2, 725.8), consisted of distributing a 400-mg dose of albendazole accompanied with educational training about STH infection, treatment, and prevention. The intervention was conducted twice over the course of the study—at baseline in May 2013 and later in November 2013. We found that the deworming intervention reduced both infection prevalence and infection intensity, but these declines in infection were not accompanied by an impact on outcomes of nutrition, cognition, or school performance. Our interpretation is that the impact of deworming was attenuated by the light infection intensity in our sample population. Evidence from future RCTs is needed to assess the effect of deworming on key outcomes in areas with moderate and severe worm infections.

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Author Notes

* Address correspondence to Linxiu Zhang, Center for Chinese Agricultural Policy, Institute of Geographical Sciences and Natural Resource Research, Chinese Academy of Sciences, Beijing, China. E-mail: lxzhang.ccap@igsnrr.ac.cn

Financial support: We acknowledge financial support from the National Natural Science Foundation of China (grant nos. 71473240 and 71333012), as well as the International Initiative for Impact Evaluation (3IE, grant no. PW2.04.02.02).

Authors' addresses: Chengfang Liu and Renfu Luo, China Center for Agricultural Policy, School of Advanced Agricultural Sciences, Peking University, Beijing, China, E-mails: cfliu.ccap@pku.edu.cn and luorf.ccap@pku.edu.cn. Louise Lu, Yale University School of Medicine, New Haven, CT, and Freeman Spogli Institute, Stanford University, Stanford, CA, E-mail: louise.lu@yale.edu. Linxiu Zhang, Center for Chinese Agricultural Policy, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China, E-mail: lxzhang.ccap@igsnrr.ac.cn. Sean Sylvia, School of Economics, Renmin University of China, Beijing, China, E-mail: sean.sylvia@gmail.com. Alexis Medina and Scott Rozelle, Freeman Spogli Institute, Stanford University, Stanford, CA, E-mails: amedina5@stanford.edu and rozelle@stanford.edu. Darvin Scott Smith, Stanford University School of Medicine, Stanford, CA, E-mail: ssmith@stanford.edu. Yingdan Chen and Tingjun Zhu, National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, China, E-mails: cyingdan@126.com and ztjren@163.com.

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