The effect of temperature and UV light on infectivity of avian influenza virus (H5N1, Thai field strain) in chicken fecal manure.

Normal chicken fecal manure (pH 8.23 and 13.7% moisture) was investigated for infectivity of the avian influenza virus (AIV; H5N1). The manure was divided into three groups; each group was inoculated with AIV at 2.38 x 10(5.25) ELD50. After viral inoculation, the first group was incubated at 25 degrees C. The second group was kept at 40 degrees C, and the last group was exposed to ultraviolet light at 4-5 microw/cm2 at room temperature. After incubation, a 20% suspension of manure was filtered and the filtrates were inoculated into 9-11 day-old embryonated chicken eggs per WHO protocol (2002). The results showed that at 25 degrees C the virus lost its infectivity within 24 hours, and at 40 degrees C within 15 minutes. UV light, however, could not destroy the infectivity of the virus even after exposure for 4 hours.