Wuchereria Bancrofti - Life Cycle

Life Cycle

W. bancrofti carry out their life cycle in two hosts. Human beings serve as the definitive host and mosquitoes as their intermediate hosts. The adult parasites reside in the lymphatics of the human host. The first-stage larvae, known as microfilariae, are present in the circulation. They migrate between the deep and the peripheral circulation. W. bancrofti is a periodic strain that exhibits nocturnal periodicity. During the day, they are present in the deep veins, and during the night, they migrate to the peripheral circulation. Next, the microfilariae are transferred into a vector; the most common mosquito vector species are within the genera Culex, Anopheles, Mansonia, and Aedes. Inside the mosquito vector, also known as the intermediate host, the microfilariae mature into motile larvae called juveniles. When the mosquito vector has its next blood meal, W. bancrofti is egested via the mosquito’s proboscis into the blood stream of the new human host. The larvae move through the lymphatic system to regional lymph nodes, predominantly in the legs and genital area. The larvae develop into adult worms over the course of a year, and reach sexual maturity in the afferent lymphatic vessels. After mating, the adult female worm can produce thousands of microfilariae that migrate into the bloodstream. A mosquito vector can bite the infected human host, ingest the microfilariae, and thus repeat the life cycle of W. bancrofti.