PREVALENCE AND TRANSMISSION OF TOXOPLASMA-GONDII IN WILD BROWN-RATS, RATTUS-NORVEGICUS

Prevalence of Toxoplasma gondii within 6 UK farmstead wild rat populat ions, and 1 population maintained within a captive cat-free environmen t for 2.5 years, was examined. The mean prevalence found was 35% (n = 235), which is more than 3 times as high as all other wild rat prevale nce levels previously reported in the UK. There were no significant ag e, sex or site differences in prevalence between or within populations irrespective of habitat type or presence of cats. Taxoplasma was also maintained within the captive rat population in the absence of cats a t a prevalence, intensity, age and sex distribution similar to that of the farmstead rat populations. These results suggest, firstly, that T oxoplasma can be perpetuated within wild rat populations without the s ympatric presence of cats and secondly, that the congenital route is t he predominant route of transmission in wild rats. This study conclude s that wild rats represent a significant and persistent wildlife inter mediate host reservoir for toxoplasmosis.