Scientists Decode the Genomes of Parasitic Flatworms

Scientists have cracked the genetic code of one of the world’s deadliest water-borne parasites, opening the door for better drug treatment and prevention. The complete genetic sequence has been determined for two species of flatworms that cause schistosomiasis — commonly known as snail fever — a water-borne disease that affects more than 200 million people a year, according to the Carter Center.

The research, published in the current issue of the journal Nature, will help scientists design drugs and other compounds to fight the parasite, according to the National Institutes of Health (NIH).

“Chronic infection with Schistosoma parasites makes life miserable for millions of people in tropical countries around the globe and can lead to death,” said Anthony S. Fauci, M.D., Director of the National Institute of Allergy and Infectious Diseases (NIAID). “New drugs and other interventions are badly needed to reduce the impact of a disease that lowers quality of life and slows economic development.”

Fauci added that anemia, fever fatigue and other symptoms can make it hard for those suffering from the disease to work or attend school.

Schistosomiasis infects individuals when they wade or bathe in fresh water inhabited by tiny snails, which serve as the parasite’s intermediate host. The parasites are released into the water by the snails and burrow into bather’s skin, traveling to the blood vessels and maturing within the host’s body. Infected individuals then return the parasites to the water through urine and feces, continuing the cycle.

According to the NIH, schistosomiasis cases top 200 million every year, and some 20 million people are seriously disabled by severe anemia, chronic diarrhea, internal bleeding and organ damage caused by the worms, their eggs and autoimmune reactions. Though best known for causing chronic illness, schistosomiasis can be deadly. In sub-Saharan Africa alone, it kills some 280,000 people each year.

In an effort to find currently marketed drugs that might also be used against the disease, researchers compared their data on the parasite’s proteins to a database of existing drugs and found 66 instances of drugs that might be effective in combating schistosomiasis.

The Carter Center ranks schistosomiasis as the second most economically devastating parasitic disease behind malaria.