New Treatment Strategy May Accelerate Elimination of Lymphatic Filariasis
A promising new treatment strategy to accelerate elimination of the disfiguring neglected tropical disease lymphatic filariasis (LF) is expected to roll out later this year in Kenya – and possibly, three other countries – due to the concerted efforts of The Task Force for Global Health and its partners.
LF is a parasitic disease spread by mosquitos that affects around 120 million people worldwide and puts an estimated 800 million more people at risk. The disease can cause swelling of lymph glands in the legs and lower body, resulting in long-term disability, disfigurement and social stigma.
In 2017, the World Health Organization (WHO) endorsed a new mass treatment strategy using the triple-drug combination of ivermectin, diethylcarbamazine, and albendazole (IDA), to speed up LF elimination. Since WHO made that recommendation, Task Force programs have been working with ministries of health and other non-profit organizations to establish processes needed for using the therapy in mass drug administration (MDA).
MDA treats entire swaths of people living in areas where they could be exposed to LF infection. Until now however, countries have only used two drugs – usually albendazole combined with either diethylcarbamazine or ivermectin. The new treatment strategy requires a fresh set of assessment tools to track program outcomes and measure impact.
Many countries hope to use the new treatment to “fast-track” LF elimination; initial clinical trials indicated that the combination of three drugs was significantly more effective at reducing LF parasite counts than the two-drug regimen, suggesting that IDA could cut years off MDA timelines. While the two-drug regimen is effective, communities must use it for several years to be free of disease.
Soon after WHO issued new treatment guidelines, Merck* committed to expand its Mectizan® (ivermectin) donation by 100 million treatments annually through 2025 for LF elimination. The Task Force-based Mectizan® Donation Program (MDP) manages the donation. “This is a very exciting development,” said MDP Director, Yao Sodahlon, MD. “IDA will facilitate LF elimination in countries that are lagging behind, and MDP is excited to expand its mandate into new countries, working with old and new partners to see LF becomes a disease of the past.”
Another Task Force program, The Neglected Tropical Diseases Support Center (NTD-SC), is helping address operational issues associated with the implementation of IDA. The NTD-SC supported the pioneering efforts of the Death to Onchocerciasis and Lymphatic Filariasis (DOLF) program at Washington University in St. Louis that showed triple-drug therapy to be both effective and safe for MDA. Now, NTD-SC is working closely with the Kenyan ministry of health and partners to develop a new monitoring and evaluation framework.
A key element of the new framework is defining and validating indicators for when mass treatment can be stopped; as LF elimination reaches the last mile in some areas, determining when to stop treatment will become important for programs, especially because the therapy costs more than the two-drug regimen. “It cannot be business as usual,” said Task Force epidemiologist Katie Gass, PhD, about IDA. “Right out of the gate, the therapy’s cost and aggressive timelines demand that we do more and we do it quickly.”
Gass said certain factors made IDA more expensive than the two-drug regimen. This includes the development of new tools to measure progress and training for health workers to use the tools and carry out the treatment campaigns.
WHO recommends that IDA be dispensed annually in areas where the two-drug regimen has not yet started or been ineffective. The new treatment is projected to eliminate LF in most endemic areas within three years if sufficient numbers of people take the free medicines.
Merck’s increased donation of Mectizan makes IDA financially feasible for countries to adopt and has helped spur their willingness to roll out triple-drug therapy. “This treatment is the strongest catalyst we have seen to date toward 2020 elimination goals. It puts eliminating LF within reach,” Gass said.
*Merck is known as MSD outside the United States and Canada