Effect of Inoculum Size and Length of Infection on the Distribution of Toxocara canis Larvae in the Mouse *

Abstract

The effect of inoculum size and time on the distribution of Toxocara canis larvae in the mouse was investigated by recovering larvae from various body regions 7, 14, 28, and 56 days after administration of either 200, 600 or 1,000 infective eggs to groups of ten male mice. An analysis of variance of larval recoveries from the carcass, liver, brain and cardiopulmonary system suggests that inoculum size was a significant factor determining the proportional recovery for each of these sites. Length of infection was significant in relation to numbers of larvae in the anterior carcass, genitourinary system, brain and heart plus lungs, while length of infection and inoculum size acting in concert influenced the numbers of larvae recovered from the carcass, liver, brain, heart and lungs. Crowding effects, manifested as altered dispersion rates, were seen in the heavier infections.