The manipulation of rat behaviour by toxoplasma gondii

We review recent work testing the hypothesis that the parasite Toxoplasma gondii manipulates one of its intermediate hosts to make it behave in a way that would enhance the parasite's chance of completing its own life cycle. Both experimental and inferential evidence from wild rats and/or captive rats in semi-naturalistic environments suggest that infected rats differed from non-infected individuals in a suite of behaviours that may enhance their likelihood of being predated by cats, the parasite's definitive host:. gomfti-infected rats were found to be more active, more exploratory, less cautious of novel stimuli and more easily trapped. Also in accordance with the manipulation hypothesis, these alterations appear specific rather than due to the symptoms of some general illness. There were no differences in food intake, condition indices, other parasite load or growth rates. Moreover, infected rats did as well as non-infected individuals in terms of social status and mating success, both the products of costly and competitive activities which would be expected to be changed if the alterations were general rather than specific. © 1995, Walter de Gruyter. All rights reserved.