Clinical assessment of postinfection, postcontact and postvaccination immunity manifestation after experimental inoculation of calves with Trichophyton verrucosum culture.

Abstract

Immunity against ringworm has been well examined, but the knowledge of its development after repeated infection is limited. Therefore, the immunity developed after a single or double contact with various doses of Trichophyton verrucosum strain was investigated in calves which had or had not shown any signs of ringworm after contact with dermatophyte. In total six individual experiments were performed on 117 calves. Experimental infection with the virulent T. verrucosum strain was used to investigate the animals' immunity. Calves showing severe trichophytosis after application of high doses of T. verrucosum culture were immune to reinfection by equally high doses of this dermatophyte. A similar protection level was reached after intramuscular revaccination or after recovery from trichophytosis with moderate course induced by two inoculations of low doses. If moderate course of illness had been induced by same single dose, the immunity was lower. Animals displaying no signs of trichophytosis after inoculation with the low doses developed insufficient immunity. There was no immunity against reinfection in animals having previous contact with subinfectious doses through undamaged skin. The results obtained suggest that the level of postinfection immunity depends on the disease extent and the frequency of administration of the infectious agent. The development of postcontact immunity cannot be excluded in calves.