Food Safety Magazine, February/March 2013

SEAFOODBy Gary P. Richards, Ph.D., and David H. Kingsley, Ph.D.Noroviruses in Shellfish and Other Foods:Challenges of the 21st CenturyIf you were unfortunate enough to have a boutof norovirus illness during your lifetime, youprobably still remember it. Nothing is moredisheartening than to develop norovirus illnesswhile traveling on that well-deserved vacationor after a wedding reception or celebratorymeal at your favorite restaurant. The fact is,noroviruses are the principle cause of foodborne illness. Inthe United States alone, there are an estimated 5.5 millioncases annually. 1 Although other enteric viruses contribute tofoodborne illness, noroviruses are by far the most prevalent.Noroviruses are transmitted by ingesting the pathogen, throughcontaminated food, water or person-to-person contact. Theyare highly contagious and found in high numbers in both fecesand vomit.Norovirus particles can cause illness even in relatively smallnumbers, estimated at perhaps as few as ten. Symptoms ofteninclude projectile vomiting and explosive diarrhea, usually atthe same time, making this illness most unpleasant. Combatingnoroviruses in the food supply chain takes an all-hands-on-deckapproach involving growers, harvesters, transporters, processors,Noroviruses inmolluscan shellfishcan causefoodborne illnessfood handlers and of course, consumers. Somepractical measures to reduce noroviruses infoods involve pre- and postharvest interventions,product testing and targeted research. 2Poor Hygienic PracticesOne of the most common means for foodcontamination is poor personal hygiene, which leads to handcontamination and subsequent transfer of viruses to foods simplyby handling. Foods commonly implicated in enteric virusillness include fruits and vegetables, deli meats, bakery products,ready-to-eat foods and molluscan shellfish. Foods handledby ill workers or persons with unsanitary hands are frequentlythe source of contamination, at harvest, during transport, at thegrocery store or during food preparation and serving. Fruits,vegetables and berries may be contaminated in the field bythe harvesters’ hands, but also by polluted irrigation water orsewage-contaminated drainage ditches or septic systems in thevicinity of the farms. Maintaining clean dishes and silverwareis also important in reducing illnesses. Hand washing withsoap and water prior to harvest, transport and preparation of56 F o o d S a f e t y M a g a z i n e