EFFECT OF TOXOPLASMA-GONDII UPON NEOPHOBIC BEHAVIOR IN WILD BROWN-RATS, RATTUS-NORVEGICUS

The effect of Toxoplasma gondii on neophobic behaviour (the avoidance of novel stimuli) was assessed in four groups of wild rats with natura lly occurring Toxoplasma infection. Two groups were placed in individu al cages and tested in a series of experiments which examined the effe ct of Toxoplasma on the rat's reaction to 3 food-related novel stimuli (odour, food-container, food). A trappability study was performed on the other two groups to test whether Toxoplasma had an effect on proba bility of capture. The results show that low neophobia was significant ly associated with positive Toxoplasma titres in 3 out of 4 groups. We suggest that differences between infected and uninfected wild rats ar ise from pathological changes caused by Toxoplasma cysts in the brains of infected rats. Such behavioural changes may be selectively advanta geous for the parasite as they may render Toxoplasma-infected rats mor e susceptible to predation by domestic cats (the definitive host of To xoplasma) and, as a side-effect, more susceptible to trapping and pois oning during pest control programmes.