PREVALENCE OF VIABLE TOXOPLASMA-GONDII TISSUE CYSTS AND ANTIBODIES TOTOXOPLASMA-GONDII BY VARIOUS SEROLOGIC TESTS IN BLACK BEARS (URSUS-AMERICANUS) FROM PENNSYLVANIA

During the hunting season of 1993, hearts from 28 black bears (Ursus a mericanus) from Pennsylvania were examined for Toxoplasma gondii infec tion. Serum samples from heart blood were examined for T. gondii antib odies by the use of the modified agglutination test (MAT), the Sabin-F eldman dye test (DT), the latex agglutination test (LAT), and the indi rect hemagglutination test (IHA). One-hundred grams of myocardium from each bear were bioassayed in mice. Approximately 500 g of myocardium from 11 bears were fed to 11 cats, and feces from those cats were exam ined for T. gondii oocysts. Toxoplasma gondii MAT antibodies (greater than or equal to 1:40) were found in 22 bears in titers of 1:40 (4 bea rs), 1:80 (3 bears), 1:160 (7 bears), 1:320 (4 bears), and greater tha n or equal to 1:2,000 (4 bears). Antibodies to T. gondii by DT (greate r than or equal to 1:10), LAT (greater than or equal to 1: 32), and IH A (greater than or equal to 1:64) tests were found in 21, 9, and 6 bea rs, respectively. All 6 bears that did not have T. gondii antibodies i n MAT were also negative in DT, IHA, and LAT. Viable T.gondii was isol ated from 3 bears by bioassays in mice and from an additional 7 bears by bioassays in cats. All 10 bears that had viable T. gondii had MAT a nd DT antibodies but only 6 and 5 of them had antibodies by LAT and IH A, respectively.