Influence of ultraviolet-B (UV-B) on viability of Mycobacterium avium subsp. paratuberculosis
2004
Katayama, N. (Shizuoka-ken. Animal Husbandry Experiment Station, Fujinomiya (Japan)) | Suzuki, T. | Shibata, M. | Ootake, M. | Kamata, S. | Yokomizo, Y.
Johne's disease is transmitted occurs through the grazing of cattle in pastures contaminated with feces of paratuberculous animals. Since the ultraviolet (UV) rays included in sunlight have been considered an effective disinfectant factor in pastures, in the present study we investigated the influence of 210-320 nm UV (UV-B) irradiation on the viability of Mycobacterium avium subsp. paratuberculosis (MAP). BBM2201 and ATCC19851 strains suspended in distilled water or diluted slurry were instilled on a slide glass and exposed to UV-B irradiation. Irrespective of drying the samples, the number of viable MAP in distilled water was reduced starting at irradiation levels of 1.0kJ/square m. and decreased to an undetectable level at about 8.5kJ/square m. With Y and X indicating the log (10) of viable MAP cells in distilled water and the amount of UV-B irradiation respectively, calculations were made for Y = -0.8X+6.49 (R**2=0.96> under dried conditions and Y = -0.7X + 6.08 (R**2=0.97) under conditions of lacking drying. However. MAP in slurry survived under irradiation that is equivalent to sunlight of several months. 99.6 -98.5% of irradiated UV-B could not penetrate through a thin layer of slurry. No measurable of UV-B was found to penetrate the grass leaves. These results indicate that MAP in feces or behind grass leaves may survive for a long period even under exposure to sunlight.
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