The value of animal models for study of infection due to atypical mycobacteria.

To elucidate the present significance of animal experimentation for the solving of taxonomic and epidemiologic questions arising in the study of the various species of the so-called atypical mycobacteria, experimental results in animals are presented. The Mycobacterium avium complex in particular is discussed in detail. Guinea pigs, rabbits, hens, and white mice were infected in different ways with various doses of the mycobacteria in question. The animals were killed after a given time unless they had died spontaneously. The findings are expressed in terms of survival time, macroscopic and microscopic appearance, and the results of cultures of the organs involved. The relationship between the course of the disease in humans and the virulence of the mycobacterial strains for animals is still not a close one. In general, large inocula of organisms are needed to set up lesions in experimental animals. M. Avium serovar strains are the most virulent to experimental animals.