Prevalence of trichinellosis in the north-central United States

Diaphragms from 3,245 pigs slaughtered in the north-central states (Minnesota, Wisconsin, Iowa, South Dakota, North Dakota) were digested and examined for the larvae of Trichinella spiralis from 1983 to 1985. The animals examined originated from small family farms that raised pigs for home consumption as well as from large commercial operations. None of the animals sampled were positive for trichinae. During the same period of time, diaphragm samples were obtained from 413 bear, 222 bobcats, 21 coyotes, 749 fishers, 1 gray fox, 2 red fox, 23 martens, 260 otters, and 2 wolves. All samples were from Minnesota and were examined for larvae of T. spiralis. Two wild animals were positive for Trichinella, a bear with 1.4 larvae per gram of muscle (LPG) and a fox with 2.4 LPG. These data demonstrate a low prevalence of trichinellosis in both swine and wild animals in this region of the country.