Trichinosis: Symptoms, Diagnosis & Heart Complications
TRICHINOSIS
Trichinosis is caused by the roundworm Trichinella spiralis. When raw or incompletely cooked pork or a pork product containing living trichina larvae is eaten, the walls of the cysts are digested, liberating the microscopic larvae. Within the small intestine of the host, the freed larvae maturate during the next 2 days to adult male or female worms, and copulate. Beginning 5 days after ingestion of the infected meat and, in humans, continuing for as long as 12 weeks, the gravid adult female worms, which are partially embedded in the mucosal wall of the small bowel, give birth to larvae. The latter successively enter the lacteals of the intestinal villi, right ventricular cavity, pulmonary capillaries, and systemic circulation. By predilection the larvae penetrate skeletal muscle fibers, where they enlarge progressively, simultaneously causing degeneration of the fibers and provoking a local reaction characterized by edema, hyperemia, and granulomatous and eosinophilic inflammation. Approximately 30 days after invasion of the muscle fibers, the larvae, which now have assumed a characteristic coiled appearance, attain their maximal size and become encapsulated. In nature, the life cycle of the parasite is completed when a carnivorous mammal becomes infected with the parasite, as the result of ingesting the flesh of another animal containing living larvae (see Plate 6-146).

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