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ID#:9813
Description:This 2007 photograph depicted Center for Disease Control/ NCZVED/DPD laboratory technician, Henry Bishop holding a mass of Ascaris lumbricoides worms, which had been passed by a child in Kenya, Africa. This nematode parasitizes the human small intestine, and is spread from human to human by the fecal-oral route. Children seem to be infected more often than adults, and though the organisms depicted here originated in Africa, the disease can be acquired in the southeastern United States as well.
Adult worms live in the lumen of the small intestine. A female may produce approximately 200,000 eggs per day, which are passed with the feces. Unfertilized eggs may be ingested but are not infective. Fertile eggs embryonate and become infective after 18 days to several weeks, depending on the environmental conditions (optimum: moist, warm, shaded soil). After infective eggs are swallowed, the larvae hatch, invade the intestinal mucosa, and are carried via the portal, then systemic circulation to the lungs. The larvae mature further in the lungs (10 to 14 days), penetrate the alveolar walls, ascend the bronchial tree to the throat, and are swallowed. Upon reaching the small intestine, they develop into adult worms. Between 2 and 3 months are required from ingestion of the infective eggs to oviposition by the adult female. Adult worms can live 1 to 2 years. See the DPDx link below for a lifecycle illustration.
High Resolution: Click here for hi-resolution image (30.39 MB)
Content Providers(s):CDC/ Henry Bishop
Creation Date:2007
Photo Credit:James Gathany
Links:CDC – Div. of Parasitic Diseases: Ascariasis
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Copyright Restrictions:None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.

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