When a child is infected by parasitic worms, the worms live and grow inside the stomach and intestines. The worms can drain essential nutrients that the child eats, causing malnutrition. As the body tries to fight off the infection, appetite and metabolism are affected. Over time, the infection can cause organ damage and internal bleeding.
Intestinal worms are the most common infection affecting people living in poor communities. There are around 2.3 billion people affected – that is nearly half of the population of the world’s poorest countries. Sub-Saharan Africa, South and Southeast Asia, the Pacific Islands, and parts of Latin America are most heavily affected.
Infection affects both children and adults. In adults, infection with worms damages health and limits access to work. In the hundreds of millions of children who are infected with intestinal worms such as roundworm, hookworm, and whipworm, the effects can be particularly damaging. That is because infection and malnutrition can hinder a child’s learning and development, as well as making a child weak and sick.
In 1993, the World Bank concluded that worm infections caused the greatest burden of infectious diseases in children between 5 and 14 years in poor countries.
Worms are passed on from one person to another through contaminated food and water, and through contact with infected feces and urine. This means that infection can be rife in crowded communities with poor sanitation.
There is one single-dose drug that treats all of the main species of intestinal worms. Treatment is safe and inexpensive. The World Health Organization recommends twice-yearly treatments for pre-school children, women of childbearing age (including pregnant women and recent mothers) and adults who are at high risk.
Children with worms tend to live in poor environments where diets are often lacking, and there are other problems. This means that removing the worms is only one step in improving a child’s growth, health, and development. Deworming often needs to be supplemented with supplementary food and the delivery of targeted micronutrients, as well as catch-up education lessons.
In ‘Deworming’, a Best Practice Paper for the Copenhagen Consensus Center, Andrew Hall and Sue Horton recommend treating children when they are in school. They point out that infections are worst in children aged between 5 and 15, and schools provide a suitable place for the delivery and administration of treatment.
The financial costs of deworming schoolchildren are very small: the cost of delivering one round of treatment as part of a Child Health Day is about (US$) 15 cents when administered in school, and (US$) 25 cents for preschool children.
Hall and Horton recommend changing the World Health Organization guidelines to make deworming more effective (read more about their initiatives in the Downloadable full Guide to Giving, or in the Recommended Further Reading, under How You Can Help).
If implemented, the recommendations would lead to a lower overall cost (US$224 million annually to reach every developing country, compared to US$276 million annually), and would mean more of the spending would reach individuals who are infected by worms (74% of spending, compared to 61%), and more would be spent treating individuals who are infected with more than ten worms (31% of spending, compared to 21%).
It is possible to put a monetary value on the benefits. These benefits include the reduction in anemia and malnutrition, reduced pressure on the healthcare system,improved school participation and school achievement, and future increased productivity in working-age adults.
The research by Horton and Hall shows that the benefits are very large. For treatment of pre-school aged children, each dollar spent results in about $6 of benefits. In countries where many people are infected, the benefits of deworming can be up to 60 times higher than the costs.
Where to Find Out More
The Copenhagen Consensus research that this section draws from:
Deworming: Best Practice Paper
Andrew Hall and Sue Horton
Hunger and Malnutrition: Copenhagen Consensus 2008 Assessment Paper
Sue Horton, H. Alderman, J.A. Rivera
Education: Copenhagen Consensus 2008 Assessment Paper
Peter F. Orazem
Hunger and Malnutrition Chapter and Education Chapter
in Global Crises, Global Solutions, second edition
Edited by Bjorn Lomborg
The Expert Panel's individual rankings and further elaboration can be found in the book, Global Crises, Global Solutions, second edition.