IMMUNIZATION OF HORSES AGAINST DERMATOPHYTOSIS CAUSED BY TRICHOPHYTON-EQUINUM

An inactivated vaccine prepared from conidia and mycelial elements of Trichophyton equinum was developed to control T. equinum infection in large groups of horses. The vaccine was used in approximately 3,500 he ad of horses over a 3-year period. Incidence of new infections was red uced from 40% to essentially 0% over that period. The vaccine protecte d 87% of vaccinated horses from infection in a controlled exposure stu dy that caused infection in 52% of non-vaccinated controls. In a prolo nged pen contact study, 91% of the vaccinates remained free of infecti on, while 70% of non-vaccinates became infected. When infection did oc cur in vaccinated individuals, it was limited to a single lesion as co mpared to more widespread infection in non-vaccinated controls.