Guarding against a devastating tropical disease

Schistosomiasis is a devastating neglected tropical disease that affects as many as 250 million people, mostly in Africa, Asia and South America. This debilitating disease causes anemia, malnutrition, pervasive learning disabilities, and kills an estimated 280,000 people each year. In Wisconsin, thousands of miles from where schistosomiasis is most prevalent, the Newmark lab is working hard to find a way to prevent this disease, which predominantly afflicts the world’s poorest people.

Schistosomiasis is caused by parasitic flatworms called schistosomes. Once schistosomes enter the human body, they travel to blood vessels around the liver or bladder and cause severe health problems. A single drug, Praziquantel, is currently the only form of treatment available. However, Praziquantel is only able to kill the parasite in its adult form, and is ineffective on other stages of the parasite’s life cycle. That means Praziquantel can only help treat people who are already suffering from the disease and cannot be used preventatively. Researchers in the Newmark lab are working to develop a treatment that protects people from being infected in the first place. 

A large part of the Newmark lab’s research focuses on the complicated life cycle of these parasites. Schistosomes are found in tainted freshwater lakes and ponds, where parasite eggs hatch into tiny creatures whose sole task is to infect a specific type of snail. Once inside the snail host, the parasite produces massive numbers of offspring called cercariae that escape the snail and swim through the water hunting for their new prey: humans. The cercariae then infect unsuspecting humans by burrowing through exposed skin. 

In the 1980s, schistosome researchers Stirewalt and Lewis made a striking observation: when microscopic aquatic invertebrates called rotifers colonize the shells of snail hosts, fewer cercariae were released from the snails. Furthermore, cercarial motility and infectivity was affected. They concluded that these rotifers were releasing a small molecule with cercarial paralyzing activity into the water. For decades, the identity of this molecule remained unknown. Phil’s curiosity was piqued by this 30-year old mystery. Could a way to prevent schistosomiasis already exist in nature?  

Hunting down the molecule that paralyzes the infective schistosome stage has been a challenging mission in the Newmark Lab. But recently, work by graduate student Jiarong Gao in collaboration with Jonathan Sweedler’s lab at the University of Illinois at Urbana-Champaign, uncovered the identity of this molecule and confirmed its activity as a potent schistosome paralytic that can prevent disease transmission in the laboratory. Scientists in the Newmark Lab are now studying this molecule to see how it works, and exploring whether they can find others that work even better, toward the goal of moving us closer to a preventative therapy for schistosomiasis.

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