Brugia malayi is a nematode (roundworm), one of the three causative agents of lymphatic filariasis in humans. Lymphatic filariasis, also known as elephantiasis, is a condition characterized by swelling of the lower limbs. The two other filarial causes of lymphatic filariasis are Wuchereria bancrofti and Brugia timori, which differ from B. malayi morphologically, symptomatically, and in geographical extent.
B. malayi is transmitted by mosquitoes and is restricted to South and South East Asia. It is one of the tropical diseases targeted for elimination by the year 2020 by the World Health Organization, which has spurred vaccine and drug development, as well as new methods of vector control.