How do roundworms cause ascariasis?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

trypanosome — parasitic disease *Trypanosoma brucei* in a blood smear (Giemsa-stained light photomicrograph).

Ascariasis is a parasitic infection caused by the ingestion of fertilized eggs of the roundworm Ascaris lumbricoides, typically through contaminated food or soil.1

Once ingested, the larvae are released in the small intestine and migrate through the intestinal wall to the liver and lungs. In the lungs, they can trigger inflammation and fluid retention. After approximately 10 to 14 days, the larvae move into the airways, are coughed up, and are swallowed, returning them to the small intestine.1

There, they mature into adult worms that can grow up to 35 cm in length and survive for up to two years. These adult worms produce large quantities of eggs, which are excreted in feces to continue the cycle. While many infections are asymptomatic, heavy infestations can lead to serious health issues, including malnutrition and intestinal obstruction.1