RESUMO
Thermal resistance of the Wa strain of human rotavirus was compared with that of SA-11 simian rotavirus in a plaque assay with MA-104 cells grown in conventional cell culture medium supplemented with filtrate from reconstituted and acid-precipitated nonfat dry milk. Both viruses produced two-component survival curves at 56 and 60°C. Average D-values (min) for the Wa human virus were 306.3 at 56°C, 47.8 at 60°C, 12.3 at 62.8°C and 2.4 at 65°C, with a z-value of 4.33°C. For the SA-11 simian virus, the average D-values were 890.5 at 56°C, with a z-value of 4.35°C. These values indicate that low levels of rotavirus should be inactivated by pasteurization processes.
RESUMO
Survival of Mycobacterium bovis BCG on garden plots spray-irrigated with sewage effluent or sludge was studied to determine persistence of mycobacteria under conditions approximating current practices. The D value (90% reduction time) in effluent-sprayed soil was 11 days, and in sludge-sprayed soil it was 8 days. On effluent-sprayed radishes, the D value was 6 days, and on sludge-sprayed radishes, 4 days; however, this difference was not significant. Isolation from lettuce was too erratic to determine a true survival rate, but the organism was isolated sporadically for up to 35 days.
