Immune response of cats experimentally infected with Microsporum canis

The aim of this study was an assessment of the immune response of cats experimentally infected with M. canis and a determination of the extent of immunity acquired after recovery. Studies were carried out on 24 domestic, short-haired cats, aged 3-4 months. The resistance of the animals was assessed by reinfection, and the degree of immune response. It has been found that after recovery from an experimental infection with M. canis, the cats which remained in an infected environment for 18 weeks showed no clinical mycotic changes, whereas control animals underwent natural infection within 6 weeks and their mycosis had a typical course. Furthermore reinfection with high doses of the fungus and skin scarification failed to break down this acquired immunity. Hypersensitivity of the delayed type, encountered in cats within 3 weeks after the experimental infection, persisted for 8 months of studies. In an analogous period of time cats infected naturally demonstrated an evidently weaker response determined by the skin test. Positive results of the migration inhibition test were obtained in the period of 3-6 weeks after infection, which corresponded with the period of the persistence of the clinical mycotic changes.