Kinetics of Toxoplasma gondii infection in murine model

The course of Toxoplasma gondii (R.H. strain) infection in mice under laboratory passages is presented in this paper. Healthy Swiss albino mice of either sex, weighing 35 g inoculated with 1x10⁴ tachyzoites of T. gondii (R.H. strain) by intraperitoneal route yielded 8.4x10⁸ tachyzoites on 4th or 5th days post infection. Such mice showed typical symptoms like normal coat, severe ascites with pendulous abdomen and techypnoea exhibited by resting fore legs either on walls of the cage, or nozzle of water bottle or other resting mice and yielded a creamy colored cloudy natured peritoneal fluid on aspiration. The fluid contained teaming number of tachyzoites and was recommended for animal passages and further studies. Whereas, the animals showing extreme dullness with rough coat, anorexia, arched back appearance and pressing their tucked-up abdomen to the floor of the cage revealed wither hepatitis, enteritis, peritonitis on post mortem examination indicating bacterial infection or yielded a very clear peritoneal fluid containing more number of macrophages and very less number of tachyzoites. Hence, the tachyzoite harvest of such mice was discarded. A dose dependent lethality was observed with T. gondii (R.H. strain) infection in mice. The mice infected with approximately one, 1x10³ and 1x10⁶ tachyzoites intra-peritoneally died on 20th, 7th and 4th DPI, respectively.