Large-scale treatment (preventive chemotherapy)
Elimination of lymphatic filariasis is possible by stopping the spread of the infection. Large-scale treatment involves a single dose of 2 medicines given annually to an entire at-risk population in the following way: albendazole (400 mg) together with ivermectin (150–200 mcg/kg) or with diethylcarbamazine citrate (DEC) (6 mg/kg).
These medicines have a limited effect on adult parasites but effectively clear microfilariae from the bloodstream and prevent the spread of parasites to mosquitoes. This recommended large-scale treatment strategy, called preventive chemotherapy, when conducted annually for 4–6 years can interrupt the transmission cycle.
At the start of GPELF, 81 countries were considered endemic for lymphatic filariasis. Further epidemiological data indicated that preventive chemotherapy was not required in 9 countries. From 2000 to 2013, over 5 billion treatments were delivered to a targeted population of about 984 million individuals in 56 countries, considerably reducing transmission in many places. Recent research data show that the transmission of lymphatic filariasis in at-risk populations has dropped by 43% since the start of GPELF. The overall economic benefit of the programme during 2000–2007 is conservatively estimated at US$ 24 billion.
Currently 73 countries are considered endemic and 17 of these have successfully implemented recommended strategies and are under surveillance to demonstrate that elimination has been achieved.
However, preventive chemotherapy has not been delivered to all endemic areas and 28 countries are not on track to achieve elimination targets and stop treatment by 2020.