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Abstract
This paper discusses an outbreak of trichinosis that occurred in 1998 in Montgomery County, Ohio, and the investigation
that followed. The outbreak was associated with consumption of bear meat from a hunt in Ontario, Canada. The person who had the index case had eaten two bear burgers that were cooked rare in a microwave oven. Bear meat from the same hunt later was consumed by 15 other people at a church supper and an additional 13 people who did not attend the supper. Of the 15 attendees at the church supper who ate the bear meat, seven developed illness consistent with Trichinella infection (attack rate about 47 percent). An additional seven people attended the supper but did not eat the bear meat and did not become ill. Having eaten bear meat at the church supper was associated with an increased risk of illness (p = .05). Inadequate cooking of the bear meat resulted in the transmission of live trichinae, The 13 other people who ate the bear meat but did not attend the supper reported no illness. A total of eight people, including the person with the index case, met the case definition for trichinosis. Adequate cooking of the bear meat or consumption of uninfected portions of the meat was probably the protective factor for those who did not become ill after consuming the bear meat.
Introduction
Trichinosis is a parasitic disease caused by a nematode of the genus Trichinella, an intestinal roundworm. In addition to T. spiralis, most commonly associated with domestic pork, four other species of Trichinella are now recognized, including T nativa in arctic bears (Centers for Disease Control and Prevention [CDC], 2001a). Illness occurs after ingestion of meat that contains encysted larvae (trichinae). Stomach acids dissolve the protein cysts, releasing the larvae. The larvae pass to the small intestine, mature into adult worms, and reproduce. The trichinae then migrate to and eventually become encapsulated in the muscles. Systemic signs and symptoms usually appear eight to 15 days after ingestion of infected meat, but the time varies between five and 45 days, depending on the number of trichinae ingested. Sudden appearance of muscle soreness and pain, together with edema of the upper eyelids, is a characteristic sign. Thirst,...