Ascaridae


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Ascaridae

 

a family of roundworms which parasitize the intestines of man and vertebrate animals. Ascarids are widespread in swine (Ascaris suum) and in humans (A. lum-bricoides). The female is 25–40 cm long, the male, 15–25 cm. Eggs enter the external environment in the feces of the host. The female ascarid may produce up to 250,000 eggs in 24 hours. In the external environment, larvae develop within the eggs (10–12 days). When the eggs enter the body of the host with food or water, the larvae burst from the eggs and burrow through the mucous membrane of the intestine, penetrate the veins, and enter the liver via the portal vein; then, following a complicated route through the circulatory system, they enter the mouth again via the lungs and trachea and reach the digestive tract. The larvae become adults in the small intestine; at the end of two to two and one-half months, ascarids begin to lay eggs. One human being may be parasitized by one to several hundred ascarids. The disease caused by parisitization with ascarids is called ascariasis.

REFERENCES

Pavlovskii, E. N. Rukovodstvo po parazitologii cheloveka sucheniem o perenoschikakh transmissivnykh boleznei, 5th ed., vol. 1. Moscow-Leningrad, 1946.
Mozgovoi, A. A. Askaridaty zhivotnykh i cheloveka i vyzyvaemye imi zabolevaniia, book 1. Moscow, 1953.
Mnogotomnoe rukovodstvo po mikrobiologii, klinike i epidemiologii infektsionnykh boleznei, vol. 9. Moscow, 1968. Pages 269–698.

K. M. RYZHIKOV

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