Describe the general structure and habitat of Wuchereria bancrofti.

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Wuchereria bancrofti is a slender, thread-like (filiform) nematode parasite whose adult worms make their habitat within the human lymphatic system — specifically the lymphatic vessels and the lymph nodes, where male and female worms live coiled together, often for years. The two sexes show the typical nematode sexual dimorphism: the female worm is considerably longer and thicker than the male, and is viviparous, meaning she gives birth to large numbers of live, immature, sheathed larvae called microfilariae, releasing them directly into the surrounding lymph and blood, rather than laying resistant eggs as Ascaris does. The male worm, in contrast, is shorter and thinner, with a posterior end that is curved ventrally, a feature associated with mating while coiled together with the female inside the lymphatics. This habitat within the lymphatic system — rather than the intestine, as with Ascaris and Entamoeba — is what leads directly to t …

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CBSE 2018Set ANNUAL8 marks
$Q. Describe the life cycle of Wuchereria bancrofti with neat diagrams.$
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Wuchereria bancrofti, the filarial worm causing lymphatic filariasis (elephantiasis), completes its life cycle between a human definitive host (where adults live in lymphatics) and a Culex mosquito intermediate host/vector (where larval development occurs).

Life cycle of Wuchereria bancrofti:

Definitive host and adult location: Humans are the definitive host. Adult male and female worms (thread-like, creamy white) live coiled together in the lymphatic vessels and lymph nodes, especially of the lower limbs and genital region.

Production of microfilariae: After mating, the female worm is viviparous and releases large numbers of minute, sheathed larvae called microfilariae into the lymph, from where they enter the peripheral blood stream. These show nocturnal periodicity — they are most abundant in peripheral blood at night, coinciding with the biting activity of the Culex vector, and retreat to the deep blood vessels of the lungs during the day.

Transmission to the mosquito: When a female Culex mosquito bites an infected person at night, it ingests circulating microfilariae along with the blood meal.

Development within the mosquito: In the mosquito's gut, the microfilariae shed their sheath, penetrate the gut wall, and migrate to the thoracic (flight) muscles. There they develop through first-stage (L1) and second-stage (L2) larvae into the infective third-stage (L3) filariform larvae, which then migrate to the mosquito's proboscis, ready for transmission.

Transmission back to a human host: When the infected mosquito bites another person, the infective L3 larvae actively escape from the proboscis and enter the skin through the bite wound.

Maturation in the new human host: The larvae migrate into the lymphatic system, where they develop into adult worms over several months to years, and the cycle repeats as new adults mate and release microfilariae.

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Q.Describe the general structure and habitat of Wuchereria bancrofti.

Concept understanding — Wuchereria bancrofti and Filariasis

Q.Describe the general structure and habitat of Wuchereria bancrofti.

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