Intestinal worms are parasites, or organisms that depend upon other organisms for existence. Although many consider intestinal worms to be a problem affecting poverty-stricken people in poor countries, they are also a health problem in the United States. Infection from intestinal worms commonly results from poor sanitation, inadequate hygiene or contact with infected pets.
Upper abdominal pain, loss of appetite and diarrhea may occur with intestinal worms. Tapeworm may develop if a person ingests an infected flea from their pet. Tapeworm can also result from eating undercooked fish, pork or beef contaminated with the parasite. Tapeworm from pork and beef can grow to 15 to 30 feet in length. Hookworm can also produce abdominal pain, weight loss and diarrhea. Roundworm, or ascariasis, can cause severe abdominal pain and vomiting if the small intestine becomes blocked by the parasites -- which can grow up to one foot in length and become as thick as a pencil.
Tapeworm larvae can penetrate the intestinal wall and infect other parts of the body, producing cysts in the brain, muscles, skin and other organs. Cysts in the brain and spinal cord can produce seizures, confusion, headaches, weakness and paralysis. These cysts can be detected with CAT scans or magnetic resonance imaging.
Hookworm infection can cause serious anemia -- low red blood cell count -- in infants, children, pregnant women and malnourished people. Hookworms live in the small intestine, where they attach to the intestinal wall and suck blood. Anemia is the most serious complication of hookworm infection. Children suffering from chronic, heavy worm infestations can experience severe anemia, affecting their growth.
Pinworm infection can cause itching in the anal area, especially at night. Pinworm infection develops when eggs are swallowed. Female pinworms expel thousands of eggs into the environment. Dust containing the eggs can contaminate doorknobs, furniture and food. Egg-laden female pinworms moving from the anus often cause intense anal and vaginal itching. Hookworm is spread by walking barefoot through soil contaminated with infected feces. An allergic reaction can develop at the entry site known as "ground itch."
Tapeworm sufferers may see part of the ribbon-like worm in the stool. Presence of a worm in vomit or stool may also be the first sign of an infection with ascariasis, or roundworm.
Ascariasis -- a type of roundworm infection -- can cause symptoms similar to pneumonia, such as coughing, wheezing and fever. This occurs when larvae migrate to the lungs before intestinal infection takes place, making its diagnosis difficult. Infection at this stage can be confirmed by finding larvae in lung or stomach fluids.