Epidemiology of Lymphatic Filariasis

Abstract

Human lymphatic filariasis (LF), commonly known as elephantiasis due to appearance of elephantoid lower limbs, is caused by nematode parasites (roundworms) of the order Filariidae comprising thread-like structure. Lymphatic filariasis is transmitted from man to man by the bites of mosquitoes, particularly the brown-black common house mosquito, Culex quinquefasciatus Say, 1823. Categorized as an NTD (neglected tropical disease), it nevertheless is a major public health problem in many parts of the tropics where it imposes a severe physical, psychological and socioeconomic burden in approximately 1.4 billion people living in endemic regions. About 120 million are currently infected with LF, while nearly 76 million people suffer from damaged lymphatic and renal systems, besides 44 million people suffering symptomatically with lymphoedema, hydrocele and elephantiasis. More than 50 countries are running programmes with the objective to reduce parasite transmission and decrease the risk of infection for people living in or visiting these communities in endemic countries. India is a signatory to the World Health Assembly resolution to achieve the elimination of lymphatic filariasis by 2020 through a nationwide mass drug administration (MDA) commencing in 250 endemic districts, covering 600 million people and deploying initially diethylcarbamazine citrate (DEC) alone in 2004 and subsequently co-administering DEC with albendazole (Alb) in 2007. So far ten rounds of MDA have been implemented in the endemic states, though not without many pitfalls. The success achieved thus far is outstanding and has kindled a hope to eliminate the disease in the next few years.