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Study of Parasitic Illness Raises Health Concerns

A new study of the parasitic illness schistosomiasis has found that the potentially crippling but not lethal illness has a greater impact on society than previously thought. Experts hope the findings lead to a comprehensive approach toward helping those with a treatable illness that afflicts millions of people.

Schistosomiasis is one of a number of water-borne parasitic illnesses that is endemic throughout Africa, Asia, the Middle East.

The schistoma parasite lives in tiny snails that thrive in water contaminated with human waste. After leaving the snail, the parasite can live up to two days and enter the skin of people bathing, swimming and wading in the water.

Once inside their human hosts, the parasites nestle into blood vessels and start producing more eggs which travel to the bladder or intestines and are passed, once again, back into the water to infect more people.

The parasites can cause a range of problems, including chronic pain, liver enlargement, bleeding, blockage of the kidneys and even bladder cancer. But not in all cases, according Charles King of the Global Health and Diseases Center at Case Western Reserve University in Cleveland, Ohio.

"At different times over the last 50 years, it's been called the either the worst of the worries or the least of the worries of people in endemic areas," said Charles King.

That's because unlike AIDS or malaria, many people who are stricken with schistosomiasis can continue to work, albeit at a greatly reduced level of productivity.

Dr. King found that out when he and his colleagues combed through 135 published reports of schistomosiasis infections conducted between 1921 and 2002.

"What we saw as we went through the many, many studies that have been done over the years is that in fact the parasite does cause a significant, perhaps only moderate, form of disability but one that's very significant if you multiply it times the number of years that people carry the infection and then there are about 200 million people in the world that are infected," he said. "So, it does constitute actually a significant component of the global burden of disease."

Dr. King says children tend to be affected more than adults because they play more in water.

While the parasitic infection doesn't kill outright, experts says schistsomiasis can reduce life expectancy if untreated.

Dr. King says he undertook the study because he's seen first hand in Africa how much better people get when they are treated with an inexpensive antibiotic, praziquantel.

Experts say $70 million has been set aside by the World Health Organization and public and private partnerships to treat people who have become ill with parasitic illnesses, such as schistosomiasis.

But some observers say the study by Dr. King and his colleagues should prompt a reevaluation of the impact of treatable illnesses on the world's poor.

Among them is Lorenzo Savioli, head of Parasitic Diseases and Vector Control at the World Health Organization, who thinks there ought to be targeted programs aimed at children to treat parasitic illnesses, like schistosomiasis, before they become a lifelong affliction.

"I think people are realizing we cannot deal only with what is really visible with the diseases that just kill," said Lorenzo Savioli. "Because that is not sufficient."

The study on schistosomiasis was published in the international medical journal The Lancet.