Human Pathogenic Viruses in Food

This chapter focuses primarily on those viruses for which food-borne transmission is well documented (hepatitis A virus (HAV) and noroviruses (NoV)), and therefore, control in food production, processing, and preparation is considered relevant. General information about structural, molecular, and environmental properties of those viruses specifically implicated in food-borne illness is detailed. Three types of food commodities are usually associated with viral disease outbreaks, those being (i) molluscan shellfish contaminated during production; (ii) fresh produce items contaminated during production, harvesting, or packing; and (iii) prepared foods contaminated during preparation. Poor personal hygiene practices of infected food handlers provide the source of contamination for prepared foods. This appears to be the most important factor influencing the food-borne transmission of enteric viruses, as U.S. Centers for Disease Control and Prevention (CDC) data indicate that 50 to 95% of viral food-borne disease outbreaks are attributable to poor personal hygiene of infected food handlers. In Europe, researchers compiled data from 10 surveillance systems in the European Foodborne Virus Network, finding NoV to be the cause of >85% of all acute nonbacterial outbreaks of gastroenteritis reported between 1995 and 2000. Intrinsic and extrinsic parameters commonly used by food processors include manipulation of temperature (cooking and heating, freezing, and refrigeration), water activity, pH, gaseous environment, natural and intentionally added inhibitors, and the presence of competitive microflora. Our understanding of the importance of enteric viruses in the overall burden of food-borne disease has increased dramatically over the past 20 years.