Question

Elephantiasis is caused by a member of
A. Aschelminthes.
B. Platyhelminthes.
C. Annelida.
D. Arthropoda.

Answer 1

Hint: Elephantiasis is a vector-borne disease. In elephantiasis, the limbs are enlarged which is caused by a worm.

Complete Answer:
- The causative agent of elephantiasis is Wuchereria bancrofti is a filariasis worm. These are the endoparasite and appear as threads like, with round ends. They have bilateral symmetry and are triploblastic with an unsegmented body.
- They exhibit sexual dimorphism i.e. females and males of the same species have different characteristics.
- The filariasis worm belongs to the order filarioidea and phylum nematodes or aschelminthes.
- The filariasis worm is known to infect humans and therefore is the human parasite.
- This worm requires two hosts: an arthropod (intermediate host such as female mosquito culex) and a vertebrate for completion of its life cycle.
- An infected mosquito carries these parasites and through mosquito bites, it transfers to humans.
- In humans, larvae parasites reside in peripheral lymphatic vessels until they mature. In lymph vessels, the adult worms remain coiled together and the mature female produces larvae, called microfilaria enters the peripheral lymphatic system and causes blockage and inflammation.
- This leads to the gross enlargement of legs and genitals and the hardening of tissues. Such a condition is called filarial elephantiasis.

This, the correct answer is option A i.e. Aschelminthes.

Additional Information:
- Wuchereria bancrofti, Brugia malayi and B.timori are human parasites. W. bancrofti is usually widespread in tropical regions globally.
- It is currently endemic throughout several Western Pacific Island nations, Sub-Saharan Africa, Madagascar, and territories and parts of the Caribbean while Bancroftian filariasis also occurs majorly in South America, India, and Southeast Asia.
- The Brugia spp. associated with lymphatic filariasis occurs only in Southeast Asia. Brugia timori is restricted to the Lesser Sunda Islands of Indonesia.
- The class nematode has several orders and is known to play a role in economic importance. There are some species of nematodes that act as natural predators.
- Species of nematode break down organic matter into an ecosystem. Most nematodes feed on microscopic creatures and are an important component of the soil ecosystem.

Note: Mostly all nematodes are harmful but some are non-pathogenic, non- parasitic organisms e.g. C.elegans. This organism is the model organism for human diseases.