Parasites - Ascariasis

ascariasis

 

An estimated 807 million–1.2 billion people in the world are infected with Ascaris lumbricoides (sometimes called just Ascaris or ascariasis). Ascaris, hookworm, and whipworm are parasitic worms known as soil-transmitted helminths (STH). Together, they account for a major burden of parasitic disease worldwide. Ascariasis is now not common in the United States.

Ascaris parasites live in the intestine. Ascaris eggs are passed in the feces (poop) of infected people. If an infected person defecates outside (for example, near bushes, in a garden, or in a field), or if the feces of an infected person is used as fertilizer, worm eggs are deposited on soil. The worm eggs can then grow into a form of the parasite that can infect others. Ascariasis is caused by ingesting those worm eggs. This can happen when hands or fingers that have contaminated dirt on them are put in the mouth, or by eating vegetables or fruits that have not been carefully peeled, washed, or cooked.

People with ascariasis often show no symptoms. If symptoms occur they can be light. Symptoms include abdominal discomfort or pain. Heavy infections can block the intestines and slow growth in children. Other symptoms such as cough are due to migration of the worms through the body. Ascariasis is treatable with medication prescribed by your healthcare provider.

Humans can also be infected by pig roundworm (Ascaris suum). Ascaris lumbricoides (human roundworm) and Ascaris suum (pig roundworm) are hard to tell apart. It is unknown how many people worldwide are infected with Ascaris suum.

Images: Left/Right: Fertilized eggs of A. lumbricoides in unstained wet mounts of stool. Center: Adult female A. lumbricoides. (Credit: DPDx), Orange County Public Health Laboratory, Santa Ana, CA