EXPERIMENTAL TOXOPLASMA-GONDII INFECTION IN RACCOONS (PROCYON-LOTOR)

Six raccoons (Procyon lotor) without detectable Toxoplasma gondii anti bodies were used. Four raccoons were inoculated orally (2 with oocysts and 2 with tissue cysts) with ME49 strain of T. gondii and 2 raccoons were not inoculated with T. gondii. All raccoons remained clinically normal. Raccoons were killed between 59 and 61 days after inoculation and portions of their heart, skeletal muscle, and brain were digested in pepsin solution, and homogenates were bioassayed in mice. Toxoplasm a gondii was isolated from all 4 inoculated raccoons; from the heart o f 3, skeletal muscles of 2 and the brain of none. All 4 inoculated rac coons developed antibody titers greater-than-or-equal-to 1:1,600 in th e modified direct agglutination test (MAT) using whole formalinized ta chyzoites. Toxoplasma gondii antibody titers of the raccoons not inocu lated with T. gondii remained < 1:25, and T. gondii was not isolated f rom their tissues. It was concluded that muscle tissue from multiple s ites including the heart was the tissue of choice for conducting paras itologic surveys for T. gondii in raccoons. Evaluation of the sera of the experimentally infected raccoons in the Sabin-Feldman dye test, la tex agglutination test, and the indirect hemagglutination tests indica ted that the MAT detected antibodies faster and in higher titers than did the other serological tests.