Chinese geneticists have taken important steps in fighting the comeback of snail fever as some 13,000 genes of the parasitic worm schistosoma japonicum have been decoded.
"We have decoded about 60 to 80 percent of the worm's genes. The analysis will help control the potentially fatal disease and develop new drugs, and effective vaccines could be innovated in a few years," said Professor Han Zeguang, team leader at the China Human Genome Center in Shanghai.
Nature Genetics will publish the full text of the two-year research led by a team of scientists from China Human Genome Center and Shanghai Second Medical University in next month's issue.
The DNA research on the worm will improve understanding of the interactions between the worm and its host, the biomedical aspects of snail fever and invertebrate evolution.
Scientists have found the worm can encode mammalian-like receptors to assist maturation in humans or livestock. The worm can also modulate anti-parasite immune responses through inhibitors, molecular mimicry and other evasion strategies.
Schistosoma japonicum, one strain of schistosome, causes snail fever or schistosomiasis in humans and livestock in the Asia-Pacific region. The worm mainly lives in freshwater along the Yangtze River in Central and East China.
Carried by freshwater snails, the worm can penetrate human skin and then produce eggs in the liver to block blood flow. Chronic patients, who account for most of those contracting the disease, can experience high fever, weakness of the limbs and severe stiffness of the joints.
Snail fever was fairly prevalent until the 1950s, when rudimentary public health measures helped curb its spread. But it has been making a comeback and become one of the main public health challenges following the flood disaster along the Yangtze River in 1998.
According to Ministry of Health statistics for 2002, more than 810,000 Chinese were afflicted with the disease, but medical experts estimate the current number might be over 1 million.
(China Daily September 23, 2003)
