Immunological Studies on Experimental Infection of Guineapigs and Rabbits with Ascaris suum Goeze, 1782. I.—The Minimum Lethal Dose (M.L.D.) and the Minimum Immunizing Dose (M.I.D.) of Ascaris Eggs in Guineapigs

Publisher Website
Google Scholar
Abstract
Guineapigs infected with a lethal dose of Ascaris eggs died between the fifth and tenth day of infection. The M.L.D. was found to be 20,000 eggs. The clinical symptoms and the macroscopic lesions in the liver and lung are described. Infected guineapigs developed an active acquired immunity and repeated infection conferred a high degree of resistance on animals which were subsequently reinfected. Resistance was manifested by the survival of the host following a lethal dose of eggs, and by an inhibition of larval migration. (Less haemorrhage was found in the lung, and fewer larvae were recovered from the lungs and tracheae, after reinfection than following one infection).The M.I.D. against a reinfective lethal dose 18 days after infection was 500 eggs. The smallest immunizing dose required to give resistance to a challenge 51 days later was 10,000 eggs. This suggests that the resistance manifested at three weeks is greater than that shown after seven weeks, i.e. there is a waning of the immunity.

This publication has 12 references indexed in Scilit: