Seroepidemiologic study on the prevalence of Toxoplasma gondii and Trichinella spp. infections in black bears (Ursus americanus) in Pennsylvania, USA.

•Toxoplasma gondii antibodies were detected in 77.9% (236/303) of black bears from Pennsylvania; 87.6% (206/235) of adults, and 44.1% (30/68) of yearlings.•Antibodies to T. gondii were found in 94% (30/32) of sows and 5% (3/66) of their nursing cubs in the dens.•Antibodies to Trichinella spp. were found in 3% (6/181) of adults, and 3.6% (1/28) of yearlings; these 7 bears were also seropositive for T. gondii. No antibodies to Trichinella spp. were detected in the sera of 44 cubs tested.•The results indicate that there is no transplacental transmission of both parasites in black bears.