Effect of various doses of infectiveToxocara canis andToxocara cati eggs on the humoral response and distribution of larvae in mice

The effect of 5–2,500 infectiveToxocara canis and 5–1,000T. cati eggs on the humoral immune response and on the distribution of larvae in the organism was studied in paratenic hosts — inbred C57BL6/J mice. With each dose ofT. canis eggs the maximal antibody level was recorded on day 56 post infection and was followed by a moderate decline that lasted until day 154 of the experiment. A correlation between the antibody level and the egg count was observed only with the infective dose of 5–50 eggs. A more rapid occurrence of antibodies was recorded in mice infected with a high dose of eggs. In those given 5 and 7T. cati eggs the antibody level exceeded the extinction threshold value only from day 21 to day 84. Low doses ofT. canis (n=5) andT. cati (n=7) eggs caused a comparable distribution of larvae in mice, and the larval recoveries on day 70 post infection ranged between 10.00% and 25.74%. Following a dose of 500T. cati eggs, 22.28% of the larvae were recovered, although only 1.08% were localized in the brain. A dose of 1,000T. canis eggs yielded, 36.37% of the larvae, with as much as 28.13% being found in the brain.