Elimination of lymphatic filariasis: do we have the drugs to complete the job?

PURPOSE OF REVIEW: Lymphatic filariasis is targeted for elimination globally through mass drug administration (MDA) with diethylcarbamazine or ivermectin monotherapy, or either drug in combination with albendazole. However, many countries that have implemented MDA annually for over 5 years are yet to interrupt transmission. This review describes the current drugs used in MDA and highlights the challenges facing the WHO Global Programme to Eliminate Lymphatic Filariasis (GPELF).

RECENT FINDINGS: Current drugs used for MDA implementation by national elimination programmes only temporarily clear microfilariae without killing all adult worms. Generally, reports of serious adverse events associated with MDA for lymphatic filariasis using current drugs are uncommon. However, in areas in Africa where lymphatic filariasis co-exists with Loa loa, progressive neurologic decline and encephalopathy within a few days of taking ivermectin have caused great concern. Doxycycline, which is effective at eliminating the Wolbachia symbiont from the lymphatic filariasis parasite, is showing promise as an alternative treatment option for areas where lymphatic filariasis is co-endemic with Loa loa.

SUMMARY: Alternative and effective MDA regimens and strategies will be needed if the GPELF is to achieve the goals of global elimination of lymphatic filariasis by 2020. Further research to test new drug regimens (including single high doses of albendazole) or alternative treatment regimens (including biannual treatment schedules) may also be necessary. A new drug, moxidectin, which is currently under development for use against onchocerciasis, may be effective against lymphatic filariasis.