Microconidia suspension of Trichophyton verrucosum virulent culture isolated originally from the mycotic lesions of cattle was inoculated epicutaneously to calves in various doses. Four application methods were selected, namely, onto the sheared and gently scarified skin, onto the sheared and non-scarified skin, onto the non-sheared and gently scarified skin, and onto the non-sheared and non-scarified skin. The inoculated area was 10 x 10 cm for all cases mentioned. When the application was performed onto the sheared and scarified skin, at least 18,000 microconidia of T. verrucosum per one animal had to be used to induce the mycotic disease in 100% of animals. This value was 10 times higher when the application was performed onto the non-sheared and scarified skin, 100 times higher in the case of the sheared and non-scarified skin and 1,000 times higher in the case of the non-sheared and non-scarified skin. The minimum infectious dose still capable of inducing dermatophytosis was 180 microconidia per 100 cm(2) of the scarified skin, 18,000 microconidia per 100 cm(2) of the sheared and non-scarified skin, and 180,000 microconidia per 100 cm(2) of the non-sheared and non-scarified skin.

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The aim of the study was to test a possible extension of the period between vaccination and revaccination with the live Trichoben vaccine (Bioveta, a.s., Czech Republic). The calves (n = 61) were vaccinated intramuscularly. The intervals between vaccination and re-vaccination were 3, 5, 7, 10, 14 or 28 days. Another group of calves (n = 16) was vaccinated once with a double dose of the vaccine. The protective immunity against experimental infection with a virulent Trichophyton verrucosum CCM F-650 strain was investigated in animals one month after the last vaccination and compared with a group of non-vaccinated controls (n = 16). Clinical results were evaluated and compared using balanced two-way-ANOVA. The level of post-vaccination immunity in cattle after re-vaccination was sufficient when the intervals were 5, 7, 10, 14 and 28 days. One-time injection of a double prophylactic dose of the vaccine and a 3-day interval between vaccinations reduced the immunity and vaccine efficacy to an unsatisfactory degree. There were significant differences between the groups of calves vaccinated using an interval longer than 5 days, and the group vaccinated once with a double dose, and the group with a 3-day interval between vaccinations. The level of post-vaccination immunity in cattle after re-vaccination at the commonly used interval of 10 -14 days was identical with the immunity achieved when the interval was reduced to 5 or 7 days or extended up to 28 days. The extension of the interval between vaccinations to 5 -28 days is recommended for using the Trichoben vaccine in veterinary practice.

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.

During the last few years, reports have appeared claiming that lufenuron diminished or even cured dermatophyte infections in cats and dogs. As these observations have a rather anecdotal character leading to some ambiguity in the literature, it was decided to test lufenuron in a generally accepted animal model for dermatomycotic infection. The test was carried out in guinea pigs artificially infected with Microsporum canis on scarified dorsal skin and orally treated with lufenuron (Programä). The efficacy of up to five doses of 80 mg/kg was assessed 7 and 14 days after the start of treatment. All animals failed to show any improvement in skin lesions as compared to the vehicle-only treated animals. Clinical symptoms taken into account were scaling, crust formation, erythema, and exudation. Neither the number of treatments (one or five) nor the dose range (40 or 80 mg/ kg) made any difference. Itraconazole, tested earlier under identical circumstances, resulted in a clear and consistent improvement at day 7 of the infection at a dose of 15 mg/kg, given either in one dose or spread over several days. The absence of antimycotic activity of lufenuron in this established animal model constitutes a significant element in the discussion on the antifungal potency of lufenuron and supports the fact that there is, as yet, no evidence that benzoylphenyl urea derivative compounds have an effect on chitin synthesis in fungi.