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A new PATH for eliminating tropical diseases
SEATTLE & SEOUL—Two new rapid diagnostic tools are now commercially available for lymphatic filariasis (LF) and onchocerciasis, both of which are neglected tropical diseases (NTDs). PATH and Standard Diagnostics (SD)/Alere partnered to make these tests available.
“We are pleased to have developed two more rapid tests with PATH,” Byung-Ki Cho, vice president of Asia Pacific operations and R&D at SD/Alere, remarked in a statement. “The collaboration between SD/Alere and PATH is designed to help eliminate these NTDs and will contribute to surveillance programs and public health management with qualified products.”
The first of the two new diagnostic tools is an onchocerciasis and LF dual-detection, or “biplex” test. It is designed to close holes in surveillance data for both diseases’ control programs in parts of Africa where they are co-endemic. This could help reduce the cost to control programs, simplify use and logistics and improve coordination of decision-making among control programs. The biplex test can support such programs as they move to the disease elimination phase by monitoring post-control areas and detecting cases in low-prevalence areas. The SD BIOLINE Onchocerciasis and Lymphatic Filariasis IgG4 rapid test is based on the detection of antibodies to parasite antigens Ov16 for onchocerciasis and Wb123 for LF. Those antigens were identified and characterized by scientists at the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.
The second test is an LF monoplex test that can also be used in endemic areas where mass drug administration (MDA) has been ongoing for several years. Using antibody-detection tests in such areas can provide important information about recent transmission rates, and data from surveillance studies can be used to support decisions to continue, halt or reinstate MDA efforts. The SD BIOLINE Lymphatic Filariasis IgG4 rapid test is based on the detection of antibodies to Wb123 for LF alone.
Funding for the development of these tests came from the Bill & Melinda Gates Foundation. Moving forward, PATH is actively seeking partners to undertake demonstration and operations research studies using the new tests, and will offer technical assistance and training materials to implementation partners.
These tests join the SD BIOLINE Onchocerciasis IgG4 rapid test, a monoplex antibody-detection test for onchocerciasis post-elimination surveillance, and the Alere Filariasis Test Strip, an antigen-detection test for use in LF disease mapping and to inform the MDA stopping decision. Both tests are marketed by SD/Alere to help eliminate onchocerciasis and LF.
Jeffrey Wellhausen, commercialization officer at PATH, says that the company started working with SD/Alere in 2012, “when PATH was seeking partners for commercialization of a rapid diagnostic test for onchocerciasis which detects antibodies to the Ov16 parasite antigen.”
According to Wellhausen, several NTDs, including onchocerciasis and LF, can be treated with MDA, and over time, disease levels will drop. While obviously that is the goal, it also makes disease detection more difficult “because the very low levels of parasites remaining are much more difficult to detect, particularly when people don’t show signs of active disease.” Detecting those low levels are important, he notes, because stopping MDA too soon could allow the disease to return, which means “Knowing when to stop MDA and being able to monitor that decision post-MDA is the critical endpoint of the elimination effort.”
“Because the new tests that PATH and SD/Alere have launched detect prior disease, they can be used in regions that have undergone years of MDA, where almost no one will have active infections … In the case of onchocerciasis, if children under the age of 10 show no evidence of exposure when tested, this indicates that transmission has been halted for 10 years, and stopping MDA can be considered (which corresponds to the WHO’s recommendations). In regions where MDA has been halted, any new infection would also be found through periodic testing,” he adds.
“Funding to fill the market need for these diagnostics is not assured, but one of the important aspects of these rapid tests is that they are standalone surveillance tools requiring no infrastructure, and they are low-cost (the Ov16 test costs $1.20),” says Wellhausen. “This makes the product suitable for large-scale uptake in the resource-poor environments where they are needed.”
Onchocerciasis, also known as river blindness, is caused by a parasitic worm transmitted to humans through the bite of the blackfly. This disease causes itching, skin disfiguration and, with chronic exposure, permanent blindness. It is thought that worldwide, 169 million people are at risk for river blindness and 37 million are infected. Of those at risk, 99 percent live in Africa.
LF, the major cause of elephantiasis, is spread via mosquitoes. The disease damages the lymphatic system, resulting in serious disability, disfigurement and low quality of life across Africa and parts of Asia. Approximately 120 million people are infected with LF worldwide, with some 1.23 billion at risk. Wuchereria bancrofti is one of three species of parasitic worms responsible for LF and accounts for 90 percent of the infections globally, including all cases on the African continent. These diseases are commonly seen in the same communities.
The World Health Organization (WHO) has named 10 NTDs as serious targets to be controlled or eliminated by 2020, including LF and onchocerciasis; LF has been slated for global elimination and onchocerciasis for elimination in select African countries. PATH is one of several organizations that have pledged to support WHO’s efforts toward these goals through the London Declaration, which was established in January 2012. In addition to LF and onchocerciasis, the target diseases include blinding trachoma, Chagas disease, dracunculiasis, human African trypanosomiasis (also known as sleeping sickness), leprosy, schistosomiasis, soil-transmitted helminthiasis and visceral leishmaniasis. With the exception of soil-transmitted helminthiasis, for which the goal is disease control, all other diseases have a 2020 target of either regional or global elimination.