By Howard White, CEO, Campbell Collaboration
More than 880 million children around the world suffer from soil-transmitted helminth infections, more commonly known as worms. About one-quarter of these children are in India where over two-thirds of children are infected.
The World Health Organization recommends mass deworming programmes in countries with prevalence of more than 20 percent, with bi-annual treatment when prevalence exceeds 50 percent as it does in India. Mass deworming means all children receive the treatment regardless of their status. The treatment is cheap. So giving it to all children is cheaper than screening to see which children have worms.
The Indian government responded to this challenge by launching a national deworming programme last year, and has held National Deworming Days in 2015 and 2016. International support has been provided by organizations such as the UK-based Children Investment Fund Foundation (CIFF) which has provided US$17.7 million. CIFF’s website calls the programme ‘evidence-based’. The programme is also supported by the US-based Evidence Action, whose website says that India’s programme will ‘benefit the health and well being of hundreds of millions of children’.
Evidence Action is a partner agency of Innovations for Poverty Action, which supported perhaps the best known study of deworming. This study in western Kenya found deworming improved school attendance, not only for children who were dewormed but also for neighbouring children. This study has been the basis for the Deworm the World movement who is also working with the Indian government on its national deworming programme.
These agencies are very clear on the benefits of deworming. The Evidence Action site states ‘rigorous research has shown that they also pose a serious threat to children’s education, and productivity later in life’. Similarly one of the project documents from the programme in Bihar states that ‘Evidence from across the globe shows that deworming leads to significant improvement in outcomes related to children’s health, education, and long-term well-being’.
But this is simply not the case.
The Cochrane and Campbell Collaborations are international research networks which summarize the highest quality research on the effectiveness of economic and social programmes. Both have published reviews of deworming. The most recent of these reviews – with a shorter version in The Lancet Global Health – clearly conclude that mass deworming is not an effective intervention. The authors find that mass deworming has little to no improvement in weight, height, school attendance or cognition measured by short-term attention.
Looking at the evidence more closely we see that the study includes 12 studies from India, 10 of which are randomized controlled trials, considered the highest quality of causal evidence. None of the Indian studies found any impact on nutrition, health or education. In fact, the only studies to do so are from Africa, including the Kenyan study mentioned above.
This seems counterintuitive. Indian children have a high prevalence of worms. And deworming is efficacious. It does kill the worms. But in India this doesn’t seem to translate into improvements in nutritional status, health or education.
Why is this? There are many plausible explanations as to why deworming may be ineffective. In unclean environments – in which open defecation is common and handwashing with soap is rare – there are multiple sources of infection, including reinfection, which can simply drown out or counter any beneficial effects of deworming. There are of course many reasons children may not attend school – the demands of family labour or the need to work, poor quality schools with absent teachers, and so on. Without addressing these constraints deworming may not improve school attendance and will not improve learning performance.
Another possible reason why deworming may be ineffective is that projects often work at pilot stage but fail to have an impact when taken to scale. This is especially the case when the pilot is implemented under the close supervision of the research team, as was the case with the Kenyan study. In contrast a large study in China, supported by the International Initiative for Impact Evaluation (a global body supporting high quality impact evaluations), evaluated a deworming programme implemented through government channels, as it would be at scale. No impact was found on weight, no impact on health, and no impact on education.
It may seem rather uncaring to question mass deworming, a large programme intended to improve the lives of poor children. But it is precisely because we want to improve the lives of poor children that we have to take the evidence of no effects seriously.
So, what should we do? At a minimum, the Indian programme should include rigorous evaluation. Evidence-based development is not a blueprint approach. We shouldn’t say, it worked in Kenya so let’s do it in India. We should say, it worked in Kenya, so let’s try it and test it here. Without that testing we simply don’t do know whether deworming is a sensible ‘buy’ let alone a ‘best buy’ in development as its proponents claim.
And the emphasis on deworming should not deflect from the need for clean water and improved sanitation, all of which have proven benefits for children's wellbeing, but for which there remain challenges in getting sustained adoption, especially in poor communities.
We need to spend the marginal rupee where it has the largest marginal benefit. At present the evidence suggests that in India, that is not deworming.