CHARACTERIZATION OF TOXOPLASMA AND TRICHINELLA ISOLATES FROM MUSCLES OF BLACK BEARS IN PENNSYLVANIA

During the hunting season of 1992, 322 black bears from Pennsylvania w ere examined for Toxoplasma gondii- and Trichinella spp-induced infect ions. Toxoplasma gondii antibodies were found in 73.8% of 322 bears-ti ter < 1:25 in 65 (20.2%), 1:25 in 18 (5.6%), 1:50 in 11 (34.5%) and 1: 500 in 128 (38.7%) bears-by use of the modified agglutination test. Mu scle tissues from 89 of these bears were bioassayed for T gondii paras ites. Muscles from 64 bears, including heart from 1 bear, and heart al one from another bear, were digested in pepsin, and the digested sampl es were bioassayed in mice. Toxoplasma gondii was isolated from 5 bear s; from the heart of 1, heart and skeletal muscles of 1, and skeletal muscles of 3. The T gondii antibody titers for the 5 bears with detect able T gondii were: greater than or equal to 1:25 in all 5 bears by us e of the modified agglutination test; < 1:10 (3 bears, considered Toxo plasma-negative), 1:20 and 1:320 by use of the Sabin-Feldman dye test; < 1:64 (3 bears, considered Toxoplasma-negative), 1:128, 1:512 by use of the indirect hemagglutination test, and < 1:16 (2 bears, considere d Toxoplasma-negative), 1:32, 1:64, and 1:512 by use of the latex aggl utination test. Toxoplasma gondii was not isolated from feces of 5 cat s fed muscles from the remaining 25 bears with T gondii antibody titer < 1:25. Tissue cysts of the 4 T gondii isolates from bears were rende red noninfective by freezing at - 13 C. Antibodies against Trichinella spp were found in 6 (1.8%) of 313 bear sera; Trichinella spp larvae w ere detected in muscle digests of 2 of 63 bears, and in histologic sec tions of muscles from 3 of 162 bears. Genetic typing indicated that th e 2 Trichinella isolates from bears were a sylvatic genotype and were not the species found in domestic pigs.