Methods to Detect Viruses in Foods: Testing and Interpretation of Results ¹

Viruses that may be detected in foods should be considered pathogenic and treated with appropriate caution. In this discussion, specific procedures for extracting viruses from shellfish are presented for each of the major commercial species of bivalve molluscs. Other foods for which specific extraction methods are detailed include lettuce, frozen strawberries, ground beef and raw milk. Viruses that may be detected by the methods described are those which are capable of producing a perceptible effect while replicating in cultured primate cells. Both results that are apparently positive and those that are apparently negative require careful interpretation; one must be extremely skeptical if large numbers of food samples obtained at the market appear to yield viruses. The procedures that are now available have some important limitations, including inability to detect the viruses that cause most of the reported foodborne disease. Approaches to surmounting these limitations include use of serologic methods to detect viruses that do not cause perceptible effects in cell cultures and improvement of procedures for extracting all viruses from food samples.