School programmes for deworming may not be that effective: Research

Latest research, published on 11 July 2012, on the effect of deworming drugs on nutrition and school performance in children, commands our attention. The World Health Organization (WHO) report that more than a quarter of the world's population is infected with one or more of the soil-transmitted intestinal worms. WHO promote community and school programmes to give deworming drugs to all children in low-income countries regularly to improve nutrition, haemoglobin, cognition, school attendance, school performance and promote economic productivity. 

Given the important benefits around health and learning attributed to deworming programmes, this review looks at whether they are based on reliable evidence.

Researchers from the Cochrane Infectious Diseases Group prepared a new edition of this review – ‘Deworming drugs for soil-transmitted intestinal worms in children: effects on nutritional indicators, haemoglobin and school performance’ - using the latest methods, and incorporating recent trials. 

With over 65 thousand participants included in the analysis, the authors sought reliable information as to whether a child’s weight, haemoglobin, and their cognition (ability to reason and think), and performance and attendance at school improved with deworming. The authors included randomised controlled trials, including community trials where the randomisation was by schools, as these are the most powerful and reliable studies to detect effects.

When children were screened for infection, and then only those infected were treated, there was some modest evidence of benefit. However, in the analysis of deworming given as a single dose or repeatedly over time to children in communities where worms were common, the benefit was not clear or consistent. 

For weight, deworming did not show an effect, apart from 3 studies done over 15 years ago. In terms of haemoglobin, deworming did not appear to have any important effects; and in terms of cognition, exam performance or school attendance, data were limited, but what there was showed little or no evidence of an effect.

In terms of death the reviewers were not able to report the results of one trial of over a million children, completed in 2005, because the authors have not yet published the results.

These results have considerable significance for current global policies (promoted by the WHO, the World Bank and others), that claim substantive benefits of school programmes for deworming.

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