Question

Which parasitic worm is responsible for causing lymphatic filariasis?

• A. $ \text{Wuchereria bancrofti} $
• B. $ \text{Brugia malayi} $
• C. $ \text{Onchocerca volvulus} $
• D. $ \text{Ancylostoma duodenale} $

Hint:

Wuchereria bancrofti is the primary causative organism for lymphatic filariasis — focus on mosquito-borne helminths for GPAT.

Answer 1

The Correct Option is A

Wuchereria bancrofti is a parasitic filarial nematode that causes lymphatic filariasis, commonly known as elephantiasis. - It is transmitted to humans through the bite of infected mosquitoes (e.g., Culex, Anopheles, Aedes).

The adult worms live in the lymphatic system and block lymphatic vessels, causing severe swelling, especially in the legs, genitals, and breasts.
The disease is characterized by lymphedema, chronic inflammation, and gross enlargement of affected body parts.

Other options:

(B) Brugia malayi — Also causes lymphatic filariasis but is less prevalent than W. bancrofti. 
(C) Onchocerca volvulus — Causes onchocerciasis or “river blindness”. 
(D) Ancylostoma duodenale — A hookworm causing iron-deficiency anemia, not filariasis.
 

Answer 2

This question asks which worm causes lymphatic filariasis, a disease marked by blockage and swelling of the lymphatic vessels. The fastest way to sort through the options is to look at where each parasite actually lives in the body and what damage it causes.

1. Wuchereria bancrofti: Adult worms of this species live coiled inside the lymphatic vessels and lymph nodes, mainly in the legs, groin, and genital region. Their presence triggers inflammation and, over time, permanent blockage of lymph flow, producing the massive swelling seen in elephantiasis. This is the classic and most common cause of lymphatic filariasis worldwide.
2. Brugia malayi: This worm also settles in the lymphatic system and can cause a similar picture of lymphatic filariasis, but it is geographically limited to parts of South and Southeast Asia and accounts for a much smaller share of cases globally compared to Wuchereria bancrofti.
3. Onchocerca volvulus: Adult worms of this species live in fibrous nodules under the skin, not in the lymphatics. Microfilariae migrate to the eye and skin, causing river blindness and skin changes rather than lymphatic obstruction.
4. Ancylostoma duodenale: This is a hookworm that attaches to the lining of the small intestine and feeds on blood, leading to iron deficiency anemia. It has no connection to the lymphatic system at all.

Only Wuchereria bancrofti and Brugia malayi live in the lymphatics, and between the two, Wuchereria bancrofti is the organism responsible for the overwhelming majority of lymphatic filariasis cases and is the one this question is pointing to.

So the correct answer is Wuchereria bancrofti.