A total of 140 Memphis, Tennessee cats were studied parasitologically by means of the subinoculation of brain tissue into uninfected white mice, and Toxoplasma gondii was recovered from 34 (24.3 per cent). Similarly, four out of 35 Columbia, South Carolina cats were shown to be infected. There was little difference in prevalence by sex, but smaller cats were less frequently infected than large, mature cats.
Serological studies by means of the dye test indicated even higher prevalences, as 64.2 per cent of the Memphis sample and 28.6 per cent of the Columbia sample had positive titers. In each of the subsamples, the ratio of the number of dye test positives to the number of demonstrated infections was 2.4 to 2.8. Of the cats with dye test titers of 1:256 or over, almost all were shown to be infected parasitologically as compared with half of the cats with a titer of 1:64. Lower titers were associated with lower percentages of recovery of parasites, and only in a single instance were parasites recovered from a serologically negative cat.