Filariasis is a disease of the
lymphatic tissues which is caused by filarial worms that live in the the subcutaneous
and
lymphatic tissues of humans. The major infecting species includes Wuchereia bancrofti, Brugia malayi , Onchocerca volvulus , Loa loa. Filarial parasites infect approximately 14 crore persons world-wide. W. bancrofti has a complex life cycle. Humans are definitive hosts while Culex , Aedes and Anopheles are intermediate hosts. Infective form is the larvae in the mosquitoes that enter the afferent lymphatics and reach the draining lymph nodes to develop into adults. Adult worms cause dilatation and thickening of the walls of afferent lymphatics and sinuses of lymph nodes. Mechanical blockage, mechanical irritation and release of toxic substances of the adult worms leads to the inflammation of the lymph nodes. The valves in the lymph vessel becomes incompetent
leading to chronic lyphoedema. Death of the worm leads to total destruction of the lymphatic vessel leading to elephantiasis. Definitve diagnosis is demonstration of in parasite in blood by a "wet mount" or "stained preparation". Diethylcarbamazine (DEC) is effective in clearing microfilamia. Elevation of the affected limb, use of of elastic bandages and local foot care reduces some of the symptoms of chronic lymphatic obstruction.