Question

Which stage of Wuchereria bancrofti is infective to man
a. First stage larva
b. Second stage larva
c. Third stage larva
d. Mature worm

Answer 1

Filariasis or elephantiasis is the parasitic disease caused by the roundworms, where the infective stage of worms is spread by mosquitoes and black fly, and it is the disease mainly come under the helminthiasis.

Complete answer:
- Elephantiasis is caused by a parasitic worm, which is Wuchereria bancrofti, and it mainly affects the lymphatic system.
- There are eight known filaria worms that are capable of forming disease, and the definitive host for these worms in humans.
- Based on the body part, they affect the filariasis is classified as, Lymphatic filariasis, subcutaneous filariasis, and serous cavity filariasis.
- The person having the adult worms, releases the larval forms into the blood.
- If these larval forms are injected by the blood-sucking mosquitoes, where they enter the mosquito’s body in the thoracic body this microfilaria is converted to 1st stage, 2nd stage, and finally into the third stage larva of worms which is an infective larva, which is called infective microfilaria. The mosquito, with these infective larval forms, bite the other healthy person, the larva enters the blood of a person and infects the person.
- Where they enter the blood of humans, once mosquito bites and they enter the lymphatic system where they mature and form the adult worms.

Signs and symptoms
- The filaria worms mainly affect the Lymphatic system and lymph nodes of humans.
- This mainly causes the edema of the leg and it looks like an elephant leg, and that is the reason this disease is also called elephantiasis.
- Other symptoms it mainly affects the lower extremities, legs, vulva, Scrotum of hydrocoele, etc
- The skin of the edemated area becomes thick and dead and the underlying tissue is also dead.

Hence, the correct answer is option (C).

Note: The disease is mainly identified by observing the filaria worms or microfilariae larvae in the blood, and the treatment for filaria is mainly given by the drug, albendazole. And the prevention of disease is by controlling the mosquitoes, and maintaining hygiene, and eating freshly cooked food, etc.