Prevalence of Toxoplasma infection in cattle slaughtered at an Ohio abattoir.

Specimens of heart, diaphragm and, in 159 instances, esophagus were taken from 352 cattle slaughtered in an Ohio abattoir. The total weight of the material was 32 kg, and this was fed to 12 specific-pathogen-free cats to test for Toxoplasma infectivity. None of the 12 cats acquired Toxoplasma infection, as evidenced by their failure to excrete oocysts or to develop antibodies, and by failure to isolate Toxoplasma from their tissues by inoculation into mice. In further tests, a 650-g sample of beef from 77 of the 352 cattle was digested in 1% trypsin, then inoculated intraperitoneally into 40 mice. Toxoplasma was not isolated from the mice. Serums from 186 of the 352 cattle were inactivated at 60 C for 1 hour, then examined by the Sabin-Feldman (dye) test for antibodies to Toxoplasma. None had titers of more than 1:8. Of the 186 serums, 77 were also examined for antibodies in the indirect hemagglutination test. One had a titer of 1:64, which was considered nonspecific. Thus, evidence for Toxoplasma infection was not found in 352 cattle.