The stakes are high: more than 70 countries affected by schistosomiasis rely heavily on praziquantel, which usually works after just one dose and against all species
of schistosome worms.
Researchers at the Sackler School of Graduate Biomedical Sciences at Tufts and Tufts University School of Medicine (TUSM) have uncovered a mechanism that may help explain the severe forms of schistosomiasis, or snail fever, which is caused by
schistosome worms and is one of the most prevalent parasitic diseases in the world.
As we learn more about how
schistosomes infect their hosts and reproduce inside them, we hope to devise new strategies for controlling these devastating parasites that infect hundreds of millions of people in the developing world.
James Bennett, at the University of Michigan,
studies schistosomes in Egypt where praziquantel has been used more heavily than anywhere else in the world.
After observing important similarities between planarians and their disease - causing cousins, Newmark and former postdoctoral fellow Jim Collins (now a professor at UT Southwestern) took the radical step of applying their knowledge of planarians to studying
schistosome biology.
It is not clear exactly how praziquantel
disables schistosomes, but some scientists believe the drug may work in concert with the body's natural immunity to the parasite.
Insights gained from our basic research on planarian biology have also led us to study parasitic flatworms,
like schistosomes and tapeworms.
So far as I know (and I am not a parasitologist),
schistosomes infect humans by entering through the skin.
In the early 1970s, I majored in human biology at Brown University in Providence, Rhode Island, where my faculty adviser's research interest was in the biochemistry of
schistosomes.
We also did some field work and visited the site of
a schistosome infection that is infecting ducks that live next to the White House!
Fresh - water snails living in certain tropical regions of the world release the larval forms of
the schistosome parasite, which penetrate the skin, migrate through the body, and develop into adults that lay eggs that cause the disease.
Illustration to show the life cycle of
the schistosome parasite.
The only difference here is, hookworms and Strongyloides are soil transmitted helminthes, and
schistosomes are water transmitted.
If a person is standing in water, like a flooded rice field, for instance, where the infective stage of
schistosomes are swimming around, then a person can become infected as the schistosomes burrow through the skin and get into the blood stream.