Human Health and Disease — BIOLOGY STD 12 Science — Question

4. Tissue nematode

Explanation:

Dracunculus is a genus of nematodes that causes Dracunculiasis, also known as guinea worm disease. The disease is caused by the female. People become infected with Guinea worm by drinking water from ponds and other stagnant water containing tiny "water fleas" that carry the Guinea worm larvae.

The larvae are eaten by the water fleas that live in these water sources. Once drunk, the larvae are released from copepods in the stomach and penetrate the digestive track, passing into the body cavity. During the next 10-14 months, the female larvae grow into full-size adults.

These adults are 60-100 centimeters (2-3 feet) long and as wide as a cooked spaghetti noodle. When the adult female worm is ready to come out, it creates a blister on the skin anywhere on the body, but usually on the legs and feet.

This blister causes a very painful burning feeling and it bursts within 24-72 hours. Immersing the affected body part into water helps relieve the pain. It also causes the Guinea worm to come out of the wound and release a milky white liquid into the water that contains millions of immature larvae.

This contaminates the water supply and starts the cycle over again. For several days, the female worm can release more larvae whenever it comes in contact with water.