Molecular and biologic characteristics of Toxoplasma gondii isolates from wildlife in the United States

Toxoplasma gondii isolates can be grouped into 3 genetic lineages. Type I isolates are considered more virulent in outbred mice and have been isolated predominantly from clinical cases of human toxoplasmosis, whereas types 11 and III isolates are considered less virulent for mice and are found in humans and food animals. Little is known of genotypes of T. gondii isolates from wild animals. In the present report, genotypes of isolates of T. gondii from wildlife in the United States are described. Sera front wildlife were tested for antibodies to T. gondii with the modified agglutination test, and tissues from animals with titers of 1:25 (seropositive) were bioassayed in mice. Toxoplasma gondii was isolated from the hearts of 21 of 34 seropositive white-tailed deer (Odocoileus virginianus) from Mississippi and from 7 of 29 raccoons (Procyon lotor) 5 of 6 bobcats (Lynx rufus); and the gray fox (Urocvon cinereoargenteus), red fox (Vulpes vulpes), and coyote (Canis latrans) from Georgia. Toxoplasina gondii was also isolated from 7 of 10 seropositive black bears (Ursus americanus) from Pennsylvania by bioassay in cats. All 3 enotypes of T. gondii based on the SAG2 locus were circulating among wildlife.