Assessment of F-RNA coliphage as a potential indicator of enteric virus contamination of hog carcasses

Hepatitis E virus (HEV) is common in pigs, and some swine HEV strains are closely related to human strains. The zoonotic transmission of HEV is now well established. HEV can be detected by molecular techniques, but the significance of the presence of viral nucleic acid is questionable when foods are subjected to virus inactivation treatments. F-RNA coliphages are attractive candidates as indicators for enteric viruses because they are similar in size and survival characteristics and can be rapidly cultured. Information on the contamination of hog carcasses with enteric or hepatic viruses during slaughter is lacking. The objective of this study was to compare the incidence and levels of contamination of hog carcasses with F-RNA coliphages, HEV, total aerobic bacteria, coliforms, and Escherichia coli at different stages of the dressing process. Hog carcasses entering the commercial slaughter facility are heavily contaminated with F-RNA coliphages and HEV. Subsequent processes such as scalding, singing, and pasteurization can reduce the incidence and levels of F-RNA coliphages and HEV substantially to almost undetectable levels. Large discrepancies between the amount of viral nucleic acid and infectious F-RNA coliphage particles, both at high levels and low levels of contamination, were observed. The prevalence and levels of viable F-RNA coliphages were lower than those of total aerobic bacteria, coliforms, and E. coli in the anal area and on random sites before pasteurization. At a research abattoir, there was no overall mean reduction of viable F-RNA coliphages recovered from random sites before pasteurization and after washing, whereas overall mean reductions of 1.2, 2.6, and 2.9 log CFU for total aerobic bacteria, coliforms, and E. coli, respectively, were obtained. These findings suggest that bacteria such as coliforms and E. coli may not be suitable as indicators for enteric viruses in a meat processing environment.