Intestinal worms are parasites, deriving their nutrition from the human gut. Three types of worms can infest the human intestine: roundworms, tapeworms and flukes. The various species within these groups can live in different parts of the intestines, causing differing symptom patterns. People with mild to moderate intestinal worm infestations may not show symptoms.
Diarrhea is a common symptom of intestinal roundworm and fluke infestations including trichuriasis, ancylostomiasis, strongyloidiasis, trichinosis and fasciolopsiasis, according to "The Merck Manual for Healthcare Professionals." Diarrhea is not a typical symptom of tapeworm infestations.
Abdominal pain is a possible symptom of any of the roundworm, fluke or tapeworm infestations of the human intestine, according to the medical reference text, "Principles and Practice of Infectious Diseases." This symptom is least likely with the largest of the intestinal worms, the tapeworm. Abdominal pain associated with intestinal worms typically is cramping and intermittent. Sudden onset of severe abdominal pain may signal intestinal obstruction, which may occur with heavy infestation of the roundworms Ascaris lumbricoides.
Children are particularly susceptible nutritional deficiencies because of infestations by intestinal roundworms. As noted in "Principles and Practice of Infectious Diseases," severe cases of ancylostomiasis, strongyloidiasis, trichuriasis and ascariasis may cause growth retardation and malnutrition. Weight loss may occur with severe cases of ancylostomiasis and strongyloidiasis.
Fatigue may be a symptom of infestation with intestinal worms, especially those that feed off the blood supply flowing through the intestines. According to "The Merck Manual for Healthcare Professionals," severe cases of ancylostomiasis and strongyloidiasis may provoke anemia and fatigue. Long-standing infection with the fish tapeworm, Diphyllobothrium latum, can cause a vitamin B12 deficiency, leading to anemia. Fish tapeworm infestation also may cause fatigue.
Cough and Lung Congestion
The life cycle of some roundworms involves migration of an immature form of the worm through the lungs. The presence of the immature worms can trigger an inflammatory reaction known as pulmonary eosinophilia. Dr. David Kaufman notes in a Medline Plus entry that symptoms may include dry cough, shortness of breath, fever, chest pain and wheezing. Roundworm infestations associated with pulmonary eosinophilia include ascariasis, ancylostomiasis, strongyloidiasis and trichinosis.
Worms in the Stool
"Principles and Practice of Infectious Diseases" notes that people with tapeworm infestations, including taeniasis and diphyllobothriasis, may pass large segments of the worms in the stool. Tapeworms are the largest of the intestinal worms, and the passed segments can be substantial. On the other end of the scale are the pinworms, which are thread-like worms less than one-half inch long. These worms also be passed in the stool, but often go unnoticed.
- Merck Manual for Healthcare Professionals: Trichuriasis
- Centers for Disease Control and Prevention: Hookworm Infection
- Merck Manual for Healthcare Professionals: Hookworm infection
- Merck Manual for Healthcare Professionals: Strongyloidiasis
- “Principles and Practice of Infectious Diseases, Sixth Edition”; Gerald L. Mandell, M.D., et al., Editors; 2004