Investigation into the occurrence of toxoplasma in pharyngeal and palatine tonsils by inoculation of tonsillar tissues into mice.

Among randomly chosen persons in the age group one to seven years the generally accepted proportion of positive dye tests for Toxoplasma is about eight per cent. The 124 children in this age group studied by us represent a selected group in which a higher percentage is to be expected. The group included 63 boys and 61 girls, from whom no blood samples were available for serological investigation. An arbitrary percentage of twice the eight per cent would result in 20 cases with a positive dye test. In the four successful attempts to isolate Toxoplasma all four cases were boys. Among 20 persons aged 14 to 21 years in whom a positive dye test could actually be established, one attempt to isolate the organism in a girl of 16 years of age was successful. No generalized lymph node enlargements were mentioned in the history of the five successful cases, only relapsing laryngo-pharyngeal symptoms. In the five successful isolations the Toxoplasma organisms present in the tonsillar organs appeared not to be virulent for the mice used; the organism was recovered in the cystic form from the brains of the mice. In subsequent animal passages the virulence could be influenced by the number of cysts per inoculum.