The survival of foot-and-mouth disease virus in meat and offal

Abstract

Quantitative studies have been made of the survival of foot-and-mouth disease virus in beef and beef offals after storage at temperatures employed in the imported-meat trade.The survival of virus is closely associated with the hydrogen-ion concentration of the tissue; thus the acidity of rigor mortis of muscular tissue rapidly causes inactivation. Quick-freezing of beef suspends acid formation and active virus was demonstrated for so long as the meat was kept frozen.Thawing of quick-frozen meat initiates the suspended acid formation at an accelerated rate and rapidly produces a medium unsuitable for virus survival.Liver, kidney, rumen, lymph node and blood from diseased cattle have all been shown to be highly infective and to remain so if stored frozen. Acid formation in these tissues and in blood is not on the same scale as in muscle, and prolonged survival of virus is more likely even with delay in freezing and after thawing. This remains true of lymph node and of residual blood in vessels of a carcass in which the development of rigor mortis is complete.Feeding of infective offal to swine under experimental conditions resulted in the appearance of the disease.The significance of these observations is discussed in relation to the distribution of these products constituting a risk of spreading foot-and-mouth disease.We are indebted to Dr Ian A. Galloway, Director of this Institute, Mr L. B. A. Grace, Chief Technical Adviser on Meat Inspection of the Ministry of Food and Mr R. Bremner, Chief Executive Officer of the Meat Importers' National (Defence) Association, Ltd., for their help and advice while this work was in progress.It is a pleasure to acknowledge the technical assistance of Mr W. J. Brownsea.

Foot-and-Mouth Disease Virus Concentrations in Products of Animal Origin

“…In beef frozen immediately post‐mortem, the decrease in pH will not occur until after thawing. Significant concentrations of virus may be present in the muscle at this time, although the subsequent pH drop in the thawed meat will inactivate virus present in muscle but not that in bone marrow or lymph nodes (Henderson and Brooksby, 1948).…”

“…It is unclear whether the report regarding the survival of strain O 1 Campos in sheep slaughtered while febrile (Gomes et al., 1994) is a virus strain‐related phenomenon or a more common but unrecognized occurrence. In viraemic, febrile cattle, a pH drop was reported which successfully eliminated virus from beef chilled for 72 h (Henderson and Brooksby, 1948). It would be desirable to further investigate the effect of pre‐slaughter stress on the depletion of glycogen stores and subsequent reduced pH drop in FMD‐infected animals.…”

Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) related with the Animal health risks of feeding animals with ready to use dairy products without further treatment

“…Sellers (1968) reported a 10 4.5 >10 5 log reduction of FMDV titre after lowering pH to 6 for 30 min at 4C unless the material contained milk (40%) after which he only found a 10 2.2 log reduction in titre. However, this being said, long term infectivity of FMDV, even in meat, is unlikely to occur at a pH level of under 6.2 (Henderson and Brooksby, 1948).…”

Foot‐and‐mouth disease, its relation to meat and meat processing

“…Hof (1933) was able to demonstrate that the irregular recovery of virus from muscular tissue was associated with the hydrogen ion concentration, tissue having a low ultimate pH proving the least infective. Prolonged survival of the virus in muscle tissue is only likely if the p H is above 6.2 (Henderson & Brooksby, 1948).…”