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Parasitic Roundworm Diseases

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two Ascaris lumbricoides nematods, i.e., roundworms
Two Ascaris lumbricoides nematods, i.e., roundworms. The larger of the two is the female, while the normally smaller male is on the right. Adult female worms can be more than 12 inches long. Credit: CDC

Roundworms, or nematodes, are a group of invertebrates (animals having no backbone) with long, round bodies. They range in size from those that can be seen by the naked eye to those several hundredths of an inch long that can only be seen under a microscope.

Parasitic roundworms can live on or in humans where they can cause a variety of health problems. Most parasitic roundworm eggs or larvae (immature form) are found in the soil and enter the human body when a person picks them up on the hands and then transfers them to the mouth. The eggs or larvae also can enter the human body directly through the skin.

With the exception of the parasitic roundworm that causes trichinosis, mature adult roundworms eventually end up or live in human intestines and cause infection and disease. In trichinosis, it is the movement of the larvae through the body from the intestines and their encystment (becoming enclosed in a capsule) in muscle tissue that create serious problems.

Parasitic roundworms that infect humans are much more widespread than many of us realize. Diseases caused by these parasites affect not only poverty-stricken individuals in developing or remote areas of the world, but they also can be important health problems for people throughout the world, including in the United States.

As with other parasitic diseases, roundworm infections in the intestines are more common in warm climates than in cooler, temperate areas.

Many parasitic diseases caused by roundworms result from poor personal hygiene. Contributing factors may include

  • Lack of a clean water supply
  • Inadequate sanitation measures
  • Crowded living conditions combined with a lack of access to health care and low levels of education

The best solution is to try to prevent these diseases rather than treat or cure them.

School-age children are particularly at risk for parasitic roundworm infections. The parasitic roundworms consume nutrients (nourishing materials) from the children, which can contribute to malnutrition and developmental problems.

Types of Parasitic Roundworm Diseases

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Last Updated June 10, 2011

Last Reviewed February 25, 2009