Deworming important for children's health, has limited impact on infection in wider communities

February 28, 2013, Public Library of Science

Although they have an important impact on children's health and education, school-based deworming programmes have a limited impact on the level of infection in the wider community, according to a mathematical modeling study conducted by researchers at Imperial College London.

called soil-transmitted helminths (STH) infect more than a billion people in ; these worms rob the infected person of nutrition and negatively affect physical growth and , especially in children. They also can cause , which is especially harmful in women of child-bearing age causing , , and weakness. STH occurs primarily in where sanitation is poor, and typically affects the poorest of the poor—adding yet another burden on communities already held back by illness and .

These STH infections, which can be easily treated with drugs, are among the neglected tropical diseases that last year and made a commitment to eliminate or control. Johnson & Johnson (J&J) and GlaxoSmithKline (GSK) have made available up to 600 million doses of deworming drugs every year between now and 2020 – enough to achieve the target of treating up to 75% of school-age children at a global level. Deworming programmes often focus on administering treatments in schools because of the huge toll that infections take on children's growth and education, plus the ease of reaching large numbers of children in rural areas.

Researchers at Imperial College London used statistical analysis and simulations of STH transmission in a mathematical model to investigate whether programmes targeting schools are effective at restricting infection in the wider community. Their study, published in PLOS Neglected Tropical Diseases, concludes that although these programmes have many important benefits for school-aged children, they only target a small proportion of parasites in the community. They also showed that the impact of school-based treatment depends on the extent to which school children over-contribute to transmission in the community than adults - something which hasn't been studied since the early 1990s.

Other strategies need to be considered as part of efforts to control and eliminate STH, the authors say.

Professor Sir Roy Anderson of Imperial College London, Director of the London Centre for Neglected Tropical Disease Research and lead author of the study, said: "Following the London Declaration on , pharmaceutical companies are making large donations of treatments for soil-transmitted helminths, which is great news for reducing the burden of these parasites. To make best use of donations, we need more calculation based on sound understanding of disease transmission, as opposed to just relying on opinion.

"Since there are very few studies which look at the indirect effect of school-based treatment, we need to do more studies to estimate mixing patterns and the impact on transmission in order to design effective programmes in the future."

In an accompanying expert commentary in the same issue journal, Dr. David Addiss, Director of Children Without Worms, says the study raises critical questions which organizations working to control STH need to consider. "These results open a fundamental conversation about the goals and expectations of current global STH control efforts." Addiss notes that World Health Assembly (WHA) resolution 54.19, which set a target of treating at least 75% of school-age children with deworming drugs, also urged member states to promote access to safe water, and health education and to treat women at risk of STH.

In order to indicate the importance of the paper by Anderson and colleagues, Addiss draws on an analogy from the late 1800s: during that period, when massive trees were cut by handsaw and the logs floated down river by the hundreds to be milled, they occasionally jammed. Skilled lumberjacks could often identify a single "key log," which, once released, opened the way for all the logs to continue their journey. Addiss suggests that the paper by Anderson and colleagues reveals the presence of such a key log.

"In showing that the effect of deworming school children may have little long-term effect on STH transmission in the community, the analysis by Anderson and colleagues invites us, as a community, to clarify our goals and vision for STH control," Dr Addiss said.

Explore further: Global health researchers urge integrating de-worming into HIV care in Africa

More information: Anderson RM, Truscott JE, Pullan RL, Brooker SJ, Hollingsworth TD (2013) How Effective Is School-Based Deworming for the Community-Wide Control of Soil-Transmitted Helminths? PLoS Negl Trop Dis 7(2): e2027. doi:10.1371/journal.pntd.0002027

Addiss DG (2013) Epidemiologic Models, Key Logs, and Realizing the Promise of WHA 54.19. PLoS Negl Trop Dis 7(2): e2092. doi:10.1371/journal.pntd.0002092

Related Stories

Global health researchers urge integrating de-worming into HIV care in Africa

August 2, 2012
HIV care centers are an important and highly accessed point of care for HIV-infected children and their families in sub-Saharan Africa, but opportunities to address other health issues are being missed. Proven interventions, ...

A disproportionate burden of neglected tropical diseases found in India and South Asia

October 26, 2011
The open-access journal PLoS Neglected Tropical Diseases today published a comprehensive report showcasing the disproportionately high burden of neglected tropical diseases (NTDs) in India and South Asia. These diseases of ...

Availability and use of sanitation reduces by half the likelihood of parasitic worm infections

January 24, 2012
Access to sanitation facilities, such as latrines, reduces by half the risk of becoming infected by parasitic worms that are transmitted via soil (soil-transmitted helminths) according to a study published in this week's ...

Recommended for you

Study ends debate over role of steroids in treating septic shock

January 19, 2018
The results from the largest ever study of septic shock could improve treatment for critically ill patients and save health systems worldwide hundreds of millions of dollars each year.

New approach could help curtail hospitalizations due to influenza infection

January 18, 2018
More than 700,000 Americans were hospitalized due to illnesses associated with the seasonal flu during the 2014-15 flu season, according to federal estimates. A radical new approach to vaccine development at UCLA may help ...

Zika virus damages placenta, which may explain malformed babies

January 18, 2018
Though the Zika virus is widely known for a recent outbreak that caused children to be born with microencephaly, or having a small head, and other malformations, scientists have struggled to explain how the virus affects ...

Certain flu virus mutations may compensate for fitness costs of other mutations

January 18, 2018
Seasonal flu viruses continually undergo mutations that help them evade the human immune system, but some of these mutations can reduce a virus's potency. According to new research published in PLOS Pathogens, certain mutations ...

Study reveals how MRSA infection compromises lymphatic function

January 17, 2018
Infections of the skin or other soft tissues with the hard-to-treat MRSA (methicillin-resistant Staphylococcus aureus) bacteria appear to permanently compromise the lymphatic system, which is crucial to immune system function. ...

Fresh approach to tuberculosis vaccine offers better protection

January 17, 2018
A unique platform that resulted in a promising HIV vaccine has also led to a new, highly effective vaccine against tuberculosis that is moving toward testing in humans.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.