Social interactions of mice with congenital Toxoplasma infection.

The social interactions of male mice with subclinical congenital Toxoplasma infection towards their uninfected counterparts was assessed using a procedure based on the subdivision of behaviour into element groups. Infection had no effect on behavioural elements not directly associated with interaction. However infection was found to increase companion investigation as well as a number of elements directly associated with aggression. There was a complementary decrease in elements associated with flight behaviour. These findings suggest that congenital infection with Toxoplasma renders mice less cautious towards uninfected conspecifics and increases the tendency of adult male mice towards territorial aggression.