Wednesday 9 May 2012

Ascaris Lumbricoides

Ascaris Lumbricoides





Morphology
1) Known as the large intestinal roundworm ( intestinal nematodes ).
2) Adult female often measuring more than 30cm & adult male worm is about half this lenght.
3) Fertilized egg is broadly oval, and measures 45 - 75  μm in lenght and 35 - 50 μm in width.
4) 3 variations of eggs; fertile, infertile & decorticated egg. ( figure: 1.0 )


figure: 1.0 _ fertile egg

figure: 1.0 _ infertile egg

figure: 1.0 _ decorticated egg


Life cycle
Ingested embryonated eggs containing 2nd stage larvae that hatch in the small intestine. Larvae penetrate the intestinal wall, and migrate to hepatic portal circulation and pass to liver, right heart, pulmonary vessels and lungss, eventually reaching the trachea and pharynx. The larvae are swallowed and pass into small intestine, and become mature, where they mate. About 2 months after infection, eggs deposition occurs. Fertilized eggs passed in feces, become infective in warm, moist soil, within 2 weeks. Female worm produce infertile eggs in the absence of male worm.

Transmission and pathogenesis
1) Transmitted by fecal-oral route.
2) ingesting embryonated eggs from contaminated soil.
3) Most infection are asymptomatic. In heavy infection, nutritional deficiencies may develop.
4) may lead to obstruction ( intestinal blockage ).

Laboratory diagnosis
1) direct wet mount ( identified; fertilized or infertile eggs ).

Treatment and prevention
1) using antihelminthic; mebendazole or piperazine.
2) Good sanitizing practice. 











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