Excretion of Toxoplasma gondii oocysts in primoinfected felins with isolate III

Abstract

The objective of this study was to investigate the potential for excretion of T. gondii oocysts by felines primoinfected with the P strain, isolated III. To this end, 15 young cats seronegative to T. gondii were placed in individual cages and inoculated with 1500 T. gondii cysts from the brains of mice chronically infected with the P strain (isolate III) of the parasite. Fecal samples (total excreta) of the felines were collected individually for 15 days after inoculation (DPI). Afterwards, all samples (total excreta) were individually submitted to Sheather's technique. Afterwards, the samples were kept for 5 days in 2% sulfuric acid solution for oocyst sporulation. Subsequently, the oocysts present in the samples were quantified (in Neubauer's chamber) using optical microscopy (400x magnification). The identification of T. gondii oocysts was confirmed by morphological analysis and bioassay in mice. Of the 15 felines inoculated, only two animals did not eliminate oocysts in the faeces at any post-inoculation date. The elimination of oocysts varied from 2º to 13º DPI, the peak of this excretion being diagnosed in the 5th DPI. In total, 15,705,760 oocysts were removed from the 15 felines during the whole experimental period, which reinforces the importance of felines in the contamination of the environment and consequently the spread of toxoplasmosis.