PALO ALTO, Calif., July 21 (UPI) -- The fight against schistosomiasis, also known as snail fever, has been at a standstill for decades. In fact, the parasitic flatworm may be winning.
More than 250 million people are infected by schistosomes, the majority in the developing world. The flatworms are released into local freshwater sources by infected snails. The infection is most commonly found in Africa, Asia and South America. Prolonged infections can cause liver damage, kidney failure, infertility and bladder cancer.
Once promising drugs like praziquantel have failed to curb infection rates. But new research suggests the best weapon against schistosomiasis is a healthy population of snail-eating prawns.
Controlling snail populations used to be a common and effective tactic, but the ecological battle against schistosomiasis waned after praziquantel came on the market.
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It's not that praziquantel doesn't work. The drug knocks parasites from the intestines of infected patients relatively cheaply and effectively. The drug doesn't treat the problem at its source, however, and the majority of treated patients become reinfected by drinking or bathing in the same tainted water.
"We have to examine the drivers of infection and address transmission and reinfection cycles from both the human and environmental angles if we want to make a long-term impact," Susanne Sokolow, a research associate at Stanford's Hopkins Marine Station, said in a news release. "For schistosomiasis control, that means addressing the snails that carry the parasite."
Sokolow is the lead author of a new study on the use of predatory prawns to curb populations of schistosomes, published this week in the journal PLOS ONE.
Researchers looked at mitigation efforts in 83 different countries. The findings revealed the importance of snail-control strategies. When drugs are deployed with predatory prawns, the percentage of the local population infected by schistosomiasis drops by 90 percent.
Sokolow and her colleagues are now working to secure funding for native prawn reintroduction programs.
"In the bigger picture, for other diseases that have environmental phases, who knows what creative solutions might exist like we have seen for schistosomiasis?" Sokolow said. "Let's bring our creativity back to these important problems and think beyond the pills."
