Trichinosis in bears of western and northcentral United States.

Black bears (Ursus americanus) from 10 states were examined for Trichinella spiralis during the 1970-1975 period. Trichinae were found in 14 (3.1%) of 454 bears examined. Infected bears were found from California, seven (13.2%) of 54; Idaho, one (2.3%) of 44; and Wisconsin, six (3.8%) of 163. Trichina counts per gram of tissue obtained by the artificial digestion-Baermann method ranged from 1390 to 0.02. Six California bears and one from Wisconsin contained more than one trichina per gram, a level considered capable of inducing clinical trichinosis in man.