Prevalence of Toxoplasma gondii antibodies in hunter-killed white-tailed deer (Odocoileus virginianus) in four regions of Minnesota

Sera from 1,367 white-tailed deer (Odocoileus virginianus) from 4 geographic regions in Minnesota collected during 4 hunting seasons (1990- 1993) were tested for antibodies to Toxoplasma gondii using the modified direct agglutination test incorporating mercaptoethanol. Sera from 30% of the deer had antibody titers ≥25; 8.6% were positive at a titer of 25, 11% at a titer of 50, and 10% at a titer ≥500. There was a significant increase in seropositivity with age (P < 0.0001). Adult deer were twice as likely to be positive as yearlings; yearlings were 2.5 times as likely to be positive as fawns. There was no difference in prevalence by sex when adjusted for age (P = 0.316), nor was there age-sex interaction. Only males showed a slight increase in titer with age (P = 0.049). There were no significant differences in prevalence among the regions of northeast pine/aspen forest, southwest tall-grass prairie, southeast mixed-hardwood forest, and aspen/oak suburban park land. There were no statistically significant differences by year of collection. The prevalence of T. gondii antibodies in white-tailed deer remains high and deer hunters and consumers should ensure that venison is well-cooked or frozen prior to consumption.