LIFE CYCLE OF FILARIA PARASITE

Man is the definitive host i.e. where the mature adult male and female parasites mate and produce microfilariae whereas the mosquito is the intermediate host. The adult parasites are usually found in the lymphatic system of man. They give birth to as many as 50,000 microfilariae per day, which find their way into blood circulation. The life span of microfilaria is not exactly known which preferably may survive up to a couple of months

The parasite cycle in the mosquito begins when the microfilariae are picked up by the vector mosquitoes during their feeding on the infected person (microfilaria carrier). The microfilaria in mosquito develops into three stages and under optimum conditions of temperature and humidity; the duration of the cycle in the mosquito (extensive incubation period) is about 10-14 days. When the infective mosquito feeds on other human host, the infective larvae are deposited at the site of mosquito bite from where the infective larvae get into lymphatic system. In the human host, the infective larvae develop into adult male and female worms. The adult worms survive for about 5-8 years or sometimes as long as 15 years or more.