• An adult Ascaris lumbricoides.
• This nematode parasite inhabits the
small intestine and can measure up to 30cm in length
and 0.8 cm in diameter.
• About 1,000,000,000 people are believed to harbor these parasites.
•Ascaris lumbricoides is an intestinal roundworm.
•Infection occurs by ingestion of embryonated eggs either in fluids or food.
•The larvae emerge in the duodenum and migrate to the lungs via the portal circulation.
•About two weeks after ingestion symptoms of pneumitis develop with fever, sputum production and radiographic infiltrates.
•The larvae migrate through the alveoli in the bronchopulmonary tree, and arrive in the pharynx where they are swallowed.
•The larvae arrive in the small intestine where development into mature worms occur.
•Ascaris lumbricoides has a worldwide distribution.
•Infection rates are particularly high in warm humid tropical regions.
•The presence of few worms may be asymptomatic.
•The most common symptoms are vague abdominal pain or colicky pain.
•Large numbers of worms may present signs and symptoms of obstruction.
•Migration of adult worms may cause signs and symptoms of perforation, peritonitis, appendicitis or extrahepatic biliary obstruction.
|General Gross Description|
•Ascaris is a large roundworm more than 20 cm. in length.
•They are seen most commonly in the small intestine, or secondarily in the appendis. Rarely they migrate to the bile ducts.
•Multiple worms may be seen and these can cause obstructing balls.
•The worms may elicit little reaction, but can cause in inflammatory reaction with reddening and edema of the wall.
|General Micro Description|
•The histologic findings are quite variable ranging from little to quite marked inflammatory reactions or hypersensitivity reactions.
•If perforation has occured the findings are those of acute peritonitis.
• Sleisenger MH, Fordtran JS. Gastrointestinal disease. 5th ed. Philadelphia: Saunders, 1993.