Public health deworming programmes for soil‐transmitted helminths in children living in endemic areas

Deworming school children in low‐ and middle‐income countries

Cochrane researchers examined the effects of deworming children in areas where intestinal worm infection is common. After searching for relevant trials up to 19 September 2018, we included 50 trials with a total of 84,336 participants, and an additional trial of one million children.

What is deworming and why might it be important

Soil‐transmitted worms, including roundworms, hookworms, and whipworms, are common in tropical and subtropical areas, and particularly affect children living in poverty where there is inadequate sanitation. The World Health Organization (WHO) currently recommends that school children in many areas are regularly treated with drugs which kill these worms. Some advocates claim such programmes improve child growth, haemoglobin, cognition, school attendance, school performance, physical fitness, and survival.

What the research says

In populations of children living in endemic areas, the effect of the first, single dose of deworming drugs on weight is unclear. There was little or no effect in most studies, except for a large effect detected from one study area in Kenya, reported in two trials carried out over 30 years ago in a school where children were heavily infected with worms. This causes uncertainty, which means we do not know if a first dose or single dose of deworming impacts on weight. For height, most studies showed little or no effect, with the exception of the site in Kenya. A single dose of deworming medicine probably has no effect on haemoglobin and cognition. There is insufficient data to know if there is an effect on school attendance, school performance, or physical fitness or mortality.

In studies where children were regularly treated with deworming medicine there was little or no effect on weight in all but two trials, irrespective of whether children were heavily infected with worms or not. The two trials with large average weight gains included the Kenya study carried out over 30 years ago, and one study from India carried out over 20 years ago in a low worm burden area where later studies in the same area did not show an effect. In trials from 2000 onwards, which are more relevant given the global reduction in worm burden, there is little or no effect. This causes uncertainty and means we do not know if regularly treating children with deworming medicine improves their weight. Regularly deworming children probably has no effect on height, haemoglobin, cognition, and mortality. We do not know if there is an impact on school attendance, since the evidence is inconsistent and at high risk of bias. There is insufficient data to know if there is an effect on physical fitness.

Authors' conclusions

For public health programmes to regularly treat all children in endemic areas with deworming drugs, there is quite substantial evidence of no benefit in terms of haemoglobin, cognition, school performance, and mortality. For weight, contemporary studies do not show an effect, but unusually large effects were seen in studies over 20 years ago.