Survival of poliovirus on soft fruit and salad vegetables

A series of studies were performed, using poliovirus, to ascertain the pote ntial for enteric pathogenic viruses to survive on various foodstuffs. The extraction protocols, which could be performed in just a few hours, were de veloped for use with quantities of food that would normally constitute a po rtion for consumption. The protocols were based on elution of viruses from food surfaces, followed by differential centrifugation to remove food debri s and concentrate viruses. The studies were mostly performed using fresh pr oduce stored at refrigeration temperature for 2 weeks or so, which was cons idered to represent the maximum time elapsing between purchase and consumpt ion. Each food sample was inoculated with a viral suspension, and samples w ere analyzed immediately and at intervals throughout the experiment. Statis tical analyses were performed on the results, and the decimal reduction tim es (D-values), or number of days after which the initial virus numbers had declined by 90%, were calculated. In summary, the resulting D-values were a s follows: lettuce, 11.6 days; green onion, no decline; white cabbage, 14.2 days; fresh raspberries, no decline; and frozen strawberries, 8.4 days. Th e results showed that enteric viruses may persist on fresh fruit and vegeta bles for several days under conditions commonly used for storage in househo lds. Therefore, if contamination has occurred before purchase, there will a lways be a risk of infection from consumption of the food.