Dr. Murai Éva szerk.: Parasitologia Hungarica 19. (Budapest, 1986)
3 5 In order to maintain the strain, 3 to 5 white mice were inoculated with 10 to 10 actively moving trypanosomes under the skin of the back. The infectious material was the citrated blood of white mice, diluted in physiological saline. In each case a fatal parasitaemia developed on days 3-5 PI. Some of the mice died abruptly, but most of them after a prolonged agony. In cases when deaths had already occurred without agony, a healthy-looking mouse was killed and its blood was used for the passage. The number of trypanosomes in the blood Was determined by microscopy, at a magnification of x400, from the microorganism/red blood cell ratio. The blood of mice contains approximately 9.1x10* 2 g/L red blood cells. Infective dose 12 3 4 5 X = The number of dead mice + = The number of mice staying alive r*> Days of r death Fig. 1: Mice inoculated intraperitoneally with different numbers of Trypanosoma equiperdum RESULTS AND DISCUSSION Our objective was to determine how many trypanosomes are able to induce fatal disease in the mouse. The blood originated from mice killed in agony, was collected in 3.3 % sodium citrate solution and diluted further (from 10"* to 10" 9 )with physiological saline, pH 7.4. With each dilution five, mice were infected intraperitoneally. As it is shown in Fig. 1, a few trypanosomes were enough to kill the mice, naturally, only after a prolonged course, since the trypanosomes needed time to multiply. Some of the mice inoculated with a few trypanosomes in high dilutions remained alive but did not acquire immunity because they died after the second inoculation, similarly to the control ones. The answer to the question whether in mice subcutaneous or intraperitoneal inoculation is more favourable, can be found in Fig. 2. According to the figure, intraperitoneally inoculated mice die earlier, on the second day PI. On the other hand, subcutaneous inoculation produces a fatal septicaemia later. Subcutaneous inoculation of a few trypanosomes also results in infection. Still, for the titration of trypanosomes we used intraperitoneal inoculation which yields results sooner.
