Point-of-care test for onchocerciasis
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.
Endemic countries in Africa and the Americas
Dates of project
2010 – 2016
African Programme for Onchocerciasis Control (APOC)
National Institute of Allergy and Infections Diseases (NIAID)
Standard Diagnostics, Inc.
University of Florida
Togo Ministry of Health
University of Tubingen
Centers for Disease Control (CDC)
The Bill & Melinda Gates Foundation
Onchocerciasis is a major cause of preventable blindness around the world. Millions of people are exposed to infection by the parasite that causes onchocerciasis. Although it can be found in the Americas, most of the disease burden is in Africa, where affected individuals experience intense itching, severe skin disfiguration, and—with years of repeated exposure—permanent blindness.
Caused by parasitic worms transmitted to humans through the bite of the blackfly, onchocerciasis typically affects poor, rural communities near fast-flowing streams and rivers. An estimated 180 million people are at risk for the disease, and 37 million people are infected. In addition to its health effects, the disease leads to massive economic losses when productive agricultural lands are abandoned for fear of infection.
Programs to control blackflies with insecticides and mass treatment of affected communities with ivermectin have succeeded in reducing the disease burden. As efforts move from disease control to elimination, better diagnostic tools will be needed, especially for monitoring post-control areas for signs of reinfection and for detecting cases in low-prevalence areas. Although prevention and treatment programs have substantially reduced the burden of onchocerciasis in Africa in recent decades, shortcomings of existing diagnostic tools are hindering further progress. A new, affordable, point-of-care test will make it easier to identify cases rapidly and effectively target control efforts.
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), and provide rapid results. Although the rapid test will be unable to detect and quantitate the number of viable adult worms, which is the ideal for an onchocerciasis diagnostic test, 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 potential target application is the use of the rapid test in post-control areas. The test can be used to screen children for exposure and recent infection, indicating by inference recent or ongoing transmission. In unpublished reports, children from uncontrolled areas (without ivermectin treatment) were frequently found to test positive, whereas in areas where transmission has been interrupted, positivity in children was very infrequent. 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. Another potential target application is the use of a rapid test to delineate transmission zones. There have been discussions that a new transmission map for Africa that includes hypo-endemic areas is needed for an elimination strategy. Since it can detect light infections, test results can be used in identifying hypo-endemic areas and in delineating transmission zones, in conjunction with other ecological, entomological, and parasitological findings.
PATH is developing a rapid test for onchocerciasis that is based on the detection of antibodies to the parasite antigen Ov16. The new test will address limitations of existing diagnostic tools in use. Anticipated advantages over current methods include point-of-care use, low cost, rapid results, minimal training requirements, the need for only a finger prick to collect blood samples for analysis, and the ability to detect early infections.
The Ov16 rapid test will be used in the context of post-elimination monitoring of communities that have been treated with ivermectin for many years. The test will be used to monitor the communities to detect any possible reemergence of the infection so that immediate action can be taken.
PATH has successfully developed test prototypes that were evaluated for performance at the National Institutes of Health in April 2012. The results of the alpha prototype evaluation were excellent; the prototype met all performance benchmarks. Additionally, PATH completed a usability study to understand how users interact with the test and is incorporating the user feedback into the design of the next prototype.
In 2011, PATH completed on-site manufacturing assessments of six companies located in India, South Africa, and South Korea and identified three potential manufacturers to commercialize the test. In 2012, we selected a manufacturing partner Standard Diagnostics, Inc., (SD). In 2013, we concluded negotiations and signed a license and commercialization agreement with SD. Under the agreement, SD will manufacture and distribute the Ov16 rapid test for use in endemic countries.
PATH will be partnering with the African Programme for Onchocerciasis Control and other researchers to identify study sites for field evaluations beginning in Q1 2014.
Contact the Onchocerciasis Team
Tala de los Santos, Project Lead
Contact PATH’s Seattle headquarters