Observations on the migration and development of Toxocara vitulorum in natural and experimental hosts

Experimental infection of pregnant cows with eggs of T. vitulorum resulted in mature infections. Larvae possessing an oesophageal ventriculus were found in the milk of infected cows; these were considered to the 3rd-stage larvae of T. vitulorum. Some foster calves drinking milk from experimentally infected cows acquired T. vitulorum infections. All calves withdrawn from infected cows within 24 h of birth failed to develop T. vitulorum infections. the migration and fate of T vitolorum in an experimetnal host (the mouse) were studied. Measurements and figures are given of 1st-stage and 2nd-stage larvae from the egg, 2nd-stage larvae from the mouse, 3rd-stage larvae from bovine milk and 3rd-, 4th- and adult stages from the small intestine contents of calves. The writer concludes that T. vitulorum larvae undertake a transmammary migration in cattle and that calves acquire infection from their mothers after birth. The writter also concludes that T. vitulorum larvae undertake a somatic migration in mice