Smithsonian.com

A black fly, the vector for river blindness, with a parasitic larvae emerging from the fly’s antenna. Photo: US Department of Agriculture

River blindness, one of the world’s leading causes of blindness, begins when a small parasitic worm wiggles its way into human skin. Tracking down this parasite once it’s entered a human body is challenging. But now scientists have developed a novel, easy-to-perform test that uses a molecule found in urine to issue a diagnosis, ScienceNOW reports.

After a parasitic worm first makes it under a person’s skin, it grows into an adult and releases eggs. These eggs move through the host’s bloodstream, and if the larvae happen to wind up in a person’s eye—and this happens quite often—he or she will likely go blind. An estimated 500,000 people in sub-Saharan Africa have lost their sight this way, ScienceNOW writes.

A variety of medications are available to kill the parasites, some more effective than others. But most treatments rely upon multiple doses over time to make sure a person’s system is completely purged of worms. Figuring out whether or not a person truly is free from the pests is key to knowing when to bombard their system with anti-parasite medications and when to stop.

Currently, to see if someone is infected, doctors perform a “skin snip,” cutting off a small piece of the patient’s skin and checking for worms inside. It’s not the most effective method. Researchers from Imperial College London hope to improve detection with a new method they just presented in the Proceedings of the National Academy of Sciences. ScienceNow describes the finding:

They compared the amounts of hundreds of molecules found in urine samples of infected and healthy Africans and discovered one striking difference: An unknown molecule was present at levels six times higher in the urine samples of infected individuals than in samples from healthy people. The researchers identified the molecule as the remnant of a neurotransmitter that larval stages of the worm excrete and that is then broken down in the human body before being excreted in the urine.

The test could be ready in three years, the team says.

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