Filaria is a long, thread-like roundworm called Wuchereria Bancrofti that lives as a parasite in the bodies of human beings and animals. The male worm is shorter than the female and it has a curved tail. This is mainly found in Central Africa, Asia and the Southwest Pacific
Adult Filarial Worms (Macrofilariae) inhabiting lymphatic system of man In mainland India, Wuchereria bancrofti, the causative organism for filaria transmitted by the ubiquitous vector, Culex quinquefasciatus, has been the most predominant infection contributing to 99.4% of the problem in the country. Although the vector species breeds preferably in dirty and polluted water, it can also breed in clear water in the absence of polluted water. The infection is prevalent in both urban and rural areas.
Brugia malayi infection is mainly restricted to rural areas due to peculiar breeding habits of the vector associated with floating vegitation. Mansonia (Mansonioides) annulifera is the principal vector while M.(M) uniformis is the secondary vector for transmission of B.malayi infection.
The breeding of these mosquitoes is associated with aquatic plants such as Pistia stratiotes. In the absence of these plants, the vectors cannot breed. The vectorial role of M.(M). indiana is very limited due to its low density. Both W.bancrofti and B. malayi infections in mainland India exhibit nocturnal periodicity of microfilaria.