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ARS Home » Research » Publications at this Location » Publication #32592


item Dubey, Jitender

Submitted to: Journal of Parasitology
Publication Type: Research Notes
Publication Acceptance Date: 10/12/1994
Publication Date: N/A
Citation: N/A

Interpretive Summary: Infection by the protozoan parasite, Toxoplasma gondii is widespread in livestock and humans. Approximately 40% of adults humans in the U.S. are estimated to be infected with T. gondii. It causes mental retardation and loss of vision in congenitally infected children. The ingestion of undercooked meat infected with T. gondii is a major source of infection for humans. The role of wildlife in the transmission of T. gondii to humans is not clear. Scientists at the Beltsville Agricultural Research Center and the Indiana University of Pennsylvania have isolated viable Toxoplasma parasites from the heart tissue of 10 of 28 (35.7%) bears shot during the 1993 hunting season. Therefore, all bear meat should be cooked thoroughly before human consumption.

Technical Abstract: During the hunting season of 1993, hearts from 28 bears (Ursus americanus) from Pennsylvania were examined for Toxoplasma gondii infection. Serum samples from the heart blood were examined for T. gondii antibodies by the use of modified agglutination test (MAT), Sabin-Feldman dye test (DT), latex agglutination test (LAT), and indirect hemagglutination test (IHA). One hundred grams of myocardium from each bear was bioassayed in mice. Approximately 500 grams of myocardium from 11 bears was fed to 11 cats and feces of cats were examined 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 bears), 1:80 (3 bears), 1:160 (7 bears), 1:320 (4 bears), and greater than or equal 1:2000 (4 bears). Antibodies to T. gondii by DT (greater than or equal 1:10), LAT (greater than or equal 1:32), and IHA (greater than or equal 1:64) tests were found 21, 9, and 6 bears, respectively. All six bears that did not have T. gondii antibodies in MAT were also negative in DT, IHA and LAT. Viable T. gondii was isolated 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 and DT antibodies but only 6 and 5 of them had antibodies by LAT and IHA, respectively.