Experimental toxocariasis in mice and its effect on their behaviour.

When compared to uninfected controls, mice infected with second-stage larvae of Toxocara canis exhibited: (1) impaired motor performance, (2) increased ambulatory activity, (3) a greater relative preference for more exposed areas and (4) a greater overall preference for novel environments. The infected mice also appeared to show less approach-avoidance conflict and seemed less cautious when presented with novel stimuli. These behavioural differences were independent of measures of general health. Possible explanations for the observed behavioural deficits are discussed. Such alterations in behaviour may be implicated in the continuation of the life-cycle of this parasite by making mouse paratenic hosts more liable to capture and subsequent ingestion by canids, the definitive hosts of T. canis.