In order to evaluate the virulence and pathogenicity of tachyzoites, eight Toxoplasma gondii strains isolated from different animal species and humans - LIV IV, LIV V e S 11 isolated from swine, RH e VPS from humans, AS 28 from mice, HV III from dog and CN from cat - were inoculated in mice and rabbits. All the strains were strongly virulent for mice. Groups of mice inoculated, intraperitonially, with 10(4) tachyzoites died in an average of 6.0 to 7.8 days, after inoculation. The strains isolated more recently, LIV V and HV III (LD50 of 7 and 15 tachyzoites, respectively) were the most virulent. The RH strain showed the lowest virulence, with LD50 of 3160 tachyzoites. The LIV V strain also seems to be most virulent to rabbits.
Toxoplasma gondii; Pathogenicity; Laboratory animals
