An international team of scientists announced on Wednesday they had unravelled the genome of the parasitic worm that causes bilharzia, a disease that each year claims hundreds of thousands of lives.
The breakthrough could throw open the way to new drugs to fight a curse that rivals malaria and tuberculosis in many tropical countries, they said.
In fact, the blood fluke's genetic profile suggests it may be vulnerable to treatments already used for other diseases, the investigators said.
Bilharzia, also called schistosomiasis or snail fever, occurs when people bathe or wade in river or lake water inhabited by tiny snails that are the parasite's intermediate hosts.
The snails release the microscopic, fork-tailed parasites into the water, and these burrow into the bather's skin.
From there, they travel in the blood to the urinary and intestinal organs, including the liver, where they mature. The worms can grow up to a centimetre (0.4 of an inch) long and live five to 10 years on average in humans, although the record is 40 years.
Once inside the body, the parasites reproduce -- the female worm lives inside the thicker male -- and release thousands of eggs.
The eggs are shed in urine and faeces, which enables them to find their way back into snail-inhabited water, and thus the cycle starts again.
People infected with the fluke can suffer internal bleeding, organ damage, diarrhoea and anaemia.
Around 210 million people have been infected in 76 countries, according to a 2006 estimates, and the death toll is 280,000 each year in sub-Saharan Africa alone. Parts of the Middle East, Brazil, Venezuela and some West Indian islands are also badly affected.
The new probe, published in the British journal Nature, gathered scientists from the United States and Europe in a years-long endeavour to crack Schistosoma mansoni's genetic code.
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