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

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.