Introduction
Roundworm is a parasite that dwells in human intestines. Its scientific name is Ascaris lumbricoides, and the human infection is called ascariasis. The adult female worm can grow up to 12 inches; the male worm is usually smaller. The infection is rare in the U.S., according to the Centers for Disease Control and Prevention, only seen in rural areas. The WHO considers the infection a water-related disease because it's prevalent in parts of the world with poor or polluted water supplies. The adult worms live in the intestine, where the female worm can produce up to 200,000 eggs per day.
Life Cycle of the Roundworm
The infection starts when contaminated food or water containing infective eggs is swallowed. The infective eggs transform to larvae in the intestine. These migrate into the small veins or lymph vessels of the intestines and are carried to the lungs, where they undergo another phase of development. At the end of this phase, they migrate from the lungs into the trachea and up to the pharynx to be swallowed.
Full maturation occurs when they arrive in the intestine. The female produces millions of eggs in its lifetime (about 12 to 18 months). Not all of the eggs are fertilized by the male worms. The fertilized eggs alone are the ones that further develop into infective eggs. The eggs are passed out with feces. A warm, moist and shaded environment is conducive for the eggs to transform to an infective stage.
How the Roundworm is Transmitted
Improper hygiene following the passage of feces allows the fertilized eggs to be passed from person to person. Contaminated food and water serve as media for transmission of the worms. Food that falls on the ground that has fecal matter picks up the infection. An infected person can contaminate food if he doesn't wash his hands after defecation. Autoinfection also takes place, in which a person can re-infect himself if proper hand-washing is not practiced following defecation.
Water supplies contaminated by sewage also serve as means of transmission. In areas where human sewage is used as manure, infection follows eating of raw contaminated fruits and vegetables.
Prevention Strategies
Proper hygiene is the backbone of prevention of this infection. Avoiding contact with soil that may be contaminated with feces, and washing hands with soap and water before handling food and reheating food that falls to the ground are recommendations that would drastically reduce transmission.
Diagnosis of infected cases by stool examination for ova or adult worms and prompt treatment of such cases would eliminate the reservoir of infection. Improved and protected water supply also significantly reduces this infection.
