Burden of parasitic worm disease under-estimated
By Will Dunham
WASHINGTON (Reuters) - The impact of the parasitic worm disease called schistosomiasis is far more serious in affected areas than previously estimated and more resources are needed to fight it, U.S. researchers said on Tuesday.
Schistosomiasis is one of the most common parasitic infections globally, infecting an estimated 207 million people in 76 countries -- primarily developing nations in Asia, Africa, South America, the Caribbean and the Middle East.
The formula recognized by the World Health Organization to assess the burden imposed by various diseases in places where they are common rates this one as comparatively low.
But a team of researchers has reevaluated that burden using more recent scientific data.
Focusing on a form of the disease seen in China and the Philippines -- one of three types worldwide -- they judged that its true burden in terms of disability and other measures is seven to 46 times higher than the current estimates suggest.
"We're basically ringing the bell, saying attention must be paid," Stephen McGarvey, director of the International Health Institute at Brown University in Providence, Rhode Island who worked on the research, said in a telephone interview.
In its Global Burden of Disease program, the WHO rates the frequency, severity and duration of more than 130 major causes of illness, injury and death worldwide. Policymakers in turn may use this data to help determine funding for prevention and treatment programs, as well as research.
McGarvey said he hopes the findings convince policymakers, large charitable foundations, governments and others that more resources should be devoted to combating schistosomiasis.
The parasites that cause the disease are flatworms that live in snail-infested fresh water. Water becomes contaminated by worm eggs when infected people urinate or defecate in it.
Children and adults get infected swimming, bathing, fishing or rice farming in contaminated water. The worms enter the body through the skin and travel in the blood, causing anemia, diarrhea, internal bleeding, organ damage and, rarely, death.
"Schistosomiasis has a detrimental impact on nutrition and growth and development, and can lead to major organ damage and death," Julia Finkelstein of the Harvard School of Public Health, who worked on the study, said in a statement. "Current measures may severely underestimate the disability-related impact of the infection and need to be revised."
The researchers said 20 million people worldwide have severe and debilitating schistosomiasis. It is common in many tropical or subtropical regions, and nearly 800 million people are at risk, they said. It is not a major killer compared to other infections like malaria.
"This is a disease of poverty. If you had proper sewage disposal systems for humans or animals, you wouldn't be contaminating the environment with the eggs," McGarvey said.
The research was published in the Public Library of Science medical journal PLoS Neglected Tropical Diseases. It appears on the Internet at http://www.plosntds.org/doi/pntd.0000158.
(Editing by Todd Eastham)