New urine test detects cause of river blindness

Washington: Scientists have developed a new urine diagnostic to detect the parasitic worms that cause river blindness, also called onchocerciasis, a tropical disease that afflicts 18 to 120 million people worldwide.

The new, non-invasive test may provide an inexpensive method of determining in real time whether a person has an infection, which would give public health officials and doctors critical information for tracking outbreaks and treating current infections.

River blindness is a filarial disease, like elephantiasis, and occurs when the parasitic worm Onchocerca volvulus takes up residence in the skin. Adult worms pump out babies (microfilaria) at an alarming rate, which are ultimately re-spread by blackfly bites.

The microfilariae can migrate to the eye and die, releasing toxins and causing inflammation. People with the disease will slowly go blind without medical intervention.

Currently, onchocerciasis elimination programs rely primarily on mass drug administration of the therapy Ivermectin to suppress and eventually eliminate transmission of Onchocerca volvulus. Yet, without a means to evaluate if an infection is ongoing, it's hard to assess if prevention efforts are working--and if it's safe for people to stop taking medication.

The new lateral flow assay took over 10 years to develop, but it is now ready for manufacturing and testing in the field. The key to the assay's success was in the making of designer antibodies to detect a unique biomarker that only shows up when a human host has metabolized a worm neurotransmitter called tyramine. Humans then secrete this biomarker in urine.

The full findings are present in the journal ACS Infectious Diseases.