The decision to expand the Mectizan Donation Program comes after research conducted by Merck in collaboration with the World Health Organization that demonstrated that Mectizan is effective against lymphatic filariasis. The expanded use of Mectizan for lymphatic filariasis in Africa fits well with the existing program through which, for more than 10 years, Merck has donated Mectizan. Background on the Disease Lymphatic filariasis, commonly known as elephantiasis, is a major parasitic disease resulting in serious social and economic burden. The World Health Organization estimates that nearly 1 billion people in 73 countries are at risk from lymphatic filariasis and over 120 million are infected. It is in sub-Saharan Africa that the prevalence of onchocerciasis and loaisis, and the reactions that can occur following treatment with diethylcarbamazine, makes a medication like Mectizan so important.
Lymphatic filariasis is transmitted by mosquitoes.
The thread-like, parasitic filarial worms Wuchereria bancrofti and Brugia malayi that cause lymphatic filariasis live almost exclusively in humans. The worms lodge in the lymphatic system, the network of nodes and vessels that maintain the fluid balance in the tissues and blood, and an essential component of the body's immune system. They live for years, producing millions of immature microfilariae that circulate in the blood. To complete the life cycle, these microfilariae are picked up by mosquitoes which then transmit the disease to other humans. Since the clinical manifestations of filarial diseases develop relatively slowly, some people with lymphatic filariasis can have the disease for many years without even being aware of it.