Onchocerciasis Point-of-Care Test
Onchocerciasis, commonly known as river blindness, affects 37 million people with an estimated 180 million people in Africa at risk. For Africa to move from disease control efforts toward disease elimination, better diagnostic tools are needed, especially for monitoring post-control areas for signs of reinfection and for detecting cases in low-prevalence areas. PATH is currently developing a rapid, affordable, and field-friendly diagnostic test based on the detection of antibodies to the Onchocerca volvulus antigen, Ov16. Ultimately, the goal of the project is to make the Ov16 rapid test commercially available for purchase by the onchocerciasis community to help elimination efforts.
River blindness—also known as onchocerciasis—is a parasitic infection transmitted to humans through the bite of the blackfly. It causes itching, skin disfiguration, and with chronic exposure, permanent blindness. It also leads affected communities to abandon productive agricultural fields for fear of infection. Worldwide, 37 million people suffer from the disease, and an estimated 180 million are at risk, mostly in poor, rural communities near streams and rivers in Africa.
International partnerships have helped reduce the burden of onchocerciasis by ensuring that affected communities can access the only effective treatment, a drug called ivermectin. In many regions, a combination of mass treatment and blackfly control has decreased disease prevalence, paving the way for elimination. These efforts rely on continuous, community-wide testing, which allow control programs to target efforts and monitor recurrence. The best currently available test is an invasive, labor-intensive procedure called a skin snip. Eliminating onchocerciasis will require improved diagnostic tools.
The goal of this project is to develop an affordable rapid test that will be sufficiently specific and sensitive, easy to use with minimal training requirements, require less-invasive sampling methods (finger prick instead of skin snip), and provide faster results. It will have significant advantages over methods currently in use. Its design features make the test practical and convenient for use in the field.
In combination with other strategies, a simple, field-friendly, and affordable rapid test could be a powerful tool for use in Africa as onchocerciasis programs move from control to elimination. One target application is the use of the rapid test in post-control areas. In these places, the test can be used to screen children for exposure and recent infection, indicating recent or ongoing transmission. Together with epidemiological and entomological data, results from the rapid test could allow for timely actions to suppress possible reintroduction of infection into a given area.
PATH has collaborated with scientists at the National Institutes of Health, a South Korean manufacturer, and others to bring a new rapid test for river blindness to market. The simple, affordable test will support efforts to accelerate elimination of the disease and prevent the recurrence of river blindness in endemic areas.
The new point-of-care test developed by PATH is based on the detection of antibodies to a parasite antigen called Ov16, which was identified by scientists at the National Institute of Allergy and Infectious Diseases (NIAID). The test detects exposure to Onchocerca volvulus, the parasite that causes onchocerciasis, by checking for these antibodies in a single drop of blood from a finger prick. It is fast, accurate, easy to use, and less painful for patients than the skin-snip test.
In 2012, NIAID scientists evaluated test prototypes and found excellent performance. In addition, PATH studied how users interact with the test and used their feedback to refine the test’s design.
PATH partnered with two organizations in the endemic country of Togo to conduct field-based evaluations in early 2013. The goal of this work was to evaluate the performance of the test in field conditions. We compared the Ov16 rapid test to the two proven methods of diagnosis, the skin snip and the ELISA tests, evaluating dried blood spots in the lab collected during our field work. Using the valuable data provided by the field study, PATH further refined the test.
To bring the test to market, PATH sought a manufacturing partner that could meet regulatory and process requirements to create and effectively distribute the product at an affordable price. After onsite assessments of several candidates, we selected Standard Diagnostics (SD), a firm based in South Korea.
In early 2013, PATH transferred the technology for the test to SD, which is now pursuing regulatory approval and preparing for manufacturing. We will continue to support these efforts and facilitate introduction of the SD BIOLINE Onchocerciasis IgG4 test in local markets. PATH also began follow-up laboratory- and field-based evaluations of the test in the first half of 2014 with our previous partners in Togo. To generate an evidence base for policymakers and national program managers, we are partnering with the African Program for Onchocerciasis Control and other groups to organize field-based demonstration studies of the test.
PATH is planning to launch the Ov16 rapid test in late 2014. The new test, together with mass drug treatment, has the potential to help vulnerable communities finally end the suffering caused by onchocerciasis.
This program is funded by the Bill & Melinda Gates Foundation.
- Fact Sheet – Onchocerciasis point-of-care diagnostic test
- Poster, ASTMH, 2013 - Criteria for testing development of rapid diagnostic test to support onchocerciasis control and elimination programs
- PATH 2013 Annual Report – section on diagnostics
- December 2013 article in PATH newsletter “Directions” about onchocerciasis test
For more information
Contact the Onchocerciasis Team
Tala de los Santos, Project Lead
Contact PATH’s Seattle headquarters