However, long standing Toxoplasma infection has recently been associated with significant alterations in rodent behaviour. In mice, long standing Toxoplasma infection is associated with increased movement, particularly short bout behavioural pattern.
Movement is increased with inhibition of the normal progression of exploratory behaviour.
Amongst rats, natural or laboratory induced Toxoplasma infection is associated with a reduction in neophobic behaviour and enhanced susceptibility to entrapment. Other parasitic infections of rats have no demonstrable effect on behaviour. Putative mechanisms by which Toxoplasma infection may lead to altered behavioral patterns include release of metabolic products from intracerebral cysts, direct effect of cysts on central nervous tissue and alteration in brain concentrations of neurochemicals such as homovanillic acid and dopamine. It is proposed that Toxoplasma infection leads to a reduction in the ability of the infected mouse to learn with shortened attention span, resulting in increased but ineffective movement when attempting familiarization with the environment. Amongst the rat population, toxoplasma infection may cause diminished fear of novel stimuli.