What’s the big deal about deworming?

When most people think about global poverty, the first thing that comes to mind probably isn’t parasitic worms. And yet, in November 2016, four of the seven top recommended charities chosen by the charity evaluator GiveWell, focused their interventions on these seemingly uninspiring infections. What is it about these worms that’s so worthy of our attention?

The Problem

Parasitic worms cause disease when their larvae burrow their way into the human body through exposed skin. This happens when a person comes into contact with infected water or soil, such as when walking without shoes or bathing in infected water. Once in the body the larvae become adults, settle down in blood vessels and start reproducing. Their eggs pass around the body and trigger an immune response, as the body of the infected person recognises the eggs as unwanted intruders. One of the most well-known parasitic worm infections is schistosomiasis (Shist-oh-so-my-a-sis, for those of you who struggle with this like I do), which is found in water sources. A number of other worms (called soil-transmitted helminths (STHs)) live in the soil, rather than water, and although they are more common than schistosomiasis, they usually have milder effects on the body.

The effects of the worms depend on which part of the body is affected. If the gastro-intestinal tract is the major site of infection then abdominal pain, diarrhoea, bleeding from the bowel and life-threatening bowel obstruction can occur. The neighbouring liver and spleen can also be damaged. If the urinary tract is more affected, then blood can be lost in the urine, and long-term damage to the kidney, bladder and ureters can occur.

Although worms can sometimes cause significant short-term illness, like bowel obstruction or large-volume bleeding, it is more common that they cause mild symptoms only, but the disease surreptitiously causes damage over the long term. Chronic bleeding can cause significant anaemia. This, and the effort required by the body to maintain the immune system’s battle against the disease, can cause fatigue, poor growth and reduced ability to learn and work. Chronic infection also causes progressive damage to vital organs of the body, leading to a greater risk of organ failure and cancer. Although schistosomiasis is such an insidious disease it is difficult to know its full impact; the World Health Organization estimates that 200,000 deaths are caused by schistosomiasis around the world, each year. It’s estimated that at least 200 million people are infected with schistosomiasis, and that more than 1.5 billion people are infected with at least one of the soil transmitted helminths.

The Solution

So that’s a bleak picture, but now for the hopeful part. These unwelcome worms can be easily treated with medications such as praziquantel and albendazole, drugs that carry very little risk of unwanted side effects. The catch is that as long as the wormy parasites are living in water-ways and in the soil, people are at risk of getting re-infected. So a system of recurring treatment is required to remove the burden of schistosomiasis and STHs. The WHO recommends yearly deworming treatment for pre-school and school-aged children living in areas where worms are endemic. This is where organizations like the Schistosomiasis Control Initiative (SCI) and Deworm the World Initiative (DtWI) come in.

Using the World Health Organization’s drug donation programme for praziquantel and albendazole, SCI works with Ministries of Health to implement mass deworming programmes across sub-Saharan Africa. SCI coordinates a network of community based treatment programmes that train local staff to administer the drugs in their communities. The work consists of mapping out communities requiring treatment, planning and procuring the treatment, training local staff, and conducting monitoring, evaluation and research.

DtWI, which is lead by a larger organisation called Evidence Action, uses a similar model of partnering with governments to implement mass deworming programs. They currently work in India, Kenya, Ethiopia and Nigeria. Like SCI, they work to map out communities that will benefit from deworming, planning and managing the program, training people to conduct the program, building community awareness, and conducting monitoring and evaluation.

Deworming programs have gathered significant supporters. They are listed as one of the “best buys” in both education and health by the Abdul Latif Jameel Poverty Action Lab and have been recommended by the Copenhagen Consensus think tank. SCI and DtWI have both been consistently listed as a top charity by GiveWell (SCI since 2011 and DtWI since 2013). Why is this? We know that worms affect a lot of people, and there is a treatment available, but the same can be said about a lot of disease. So why are worms in particularly getting all this attention?

The Explanation

The simple answer is that mass deworming programs make treating schistosomiasis and STHs very, very cheap, and the benefits of treatment could be significant improvements in educational achievement and earning capacity, which have the potential to improve many lives. Because mass deworming occurs on a large scale, without testing for the disease, and because many of the drugs are donated, the cost of getting a child treated is less than $0.50 US dollars.

Deworming carries the benefit of avoiding both the common, mild health effects of worms (like anaemia and mild pains), and the rarer, more serious consequences (like organ failure, cancer and death). But, although avoiding these problems is undoubtedly a good thing, this isn’t the main reason places like GiveWell are so enthusiastic about deworming. What’s potentially more important is the potential for deworming to impact a child’s ability to learn and their future earning potential. A few studies have found that deworming children results in a marked increase in test scores and in future earning potential. Whilst there has been some criticism of these studies and we don’t have enough data to know conclusively how large this effect is, deworming remains a highly recommended intervention because its costs are so small, and its potential benefit is so very large.

The Next Step

Parasitic worms are not the sexiest topic you could bring up at your next dinner party. But, they have the potential to make a big impact on many people’s quality of life and opportunities. The sheer scale of the problem, and the simplicity and low cost of the solution means that giving to an organisation that works against worms may well be one of the best things you can do with your donation dollar. The commitment of SCI and DtWI to providing comprehensive, transparent programs of partnerships with governments means that you can be confident that your donation is going where you intend it to go. So, if you want to maximise the impact of your next donation consider donating to SCI or DtWI.