Baylisascaris procyonis for testing anthelmintics against migratory ascarids.

Oral inoculation of mice with 340 embryonated eggs of the nematode, Baylisascaris procyonis, proved uniformly fatal as early as 13 days after inoculation and as late as 48 days. Mice given either 0.5% or 0.25% of pyrantel tartrate in dry feed were protected from cerebral migrations of the worm for 55 days. Treatment with pyrantel pamoate in the feed at the concentration of 0.2% given 7 days before inoculation and 5 days after inoculation also protected mice from migrations throughout the 55-day experiment. Embryonated eggs stored in 0.5% formalin in a 4-C refrigerator for 9 years have proved fatal to mice given doses of 340 eggs each.