The 411 on Norovirus

Recently, there have been several outbreaks of norovirus across the United States, making people from coast to coast violently ill. News reports from across the nation roll in almost daily showing that the numbers of affected people are on the rise. But what is norovirus, and how is it spreading so quickly?

According to the CDC, noroviruses (genus Norovirus, family Caliciviridae) are a group of related, single-stranded RNA, nonenveloped viruses that cause acute gastroenteritis in humans. The virus, also called Norwalk virus- named so for a famous outbreak of the virus in Norwalk, Ohio, in 1972, when the virus was first identified- is commonly found in contaminated food products, including shellfish and some varieties of produce. It is a highly contagious virus, generally spread through food borne outbreaks. Symptoms range from mild gastroenteritis (an inflammation of the stomach and intestines) to acute gastroenteritis, characterized by diarrhea, vomiting, nausea, and occasional stomach cramping. In addition, some people with lowered immune systems have reported low-grade fevers, chills, headaches, muscle aches, and general fatigue. Those who experience the full impact of this illness begin to feel the symptoms within a relatively short time, as soon as twelve hours, and the symptoms have an average duration of one to two days. Even after the illness has run its course, the effects can linger in the form of dehydration, but this is normally confined to very young children, the elderly, and those with weakened or compromised immune systems.

The virus historically is spread through food, and usually careless or ill food handlers are the prime suspects for the transmission of the virus to a greater population. The number one preventive measure to control and eradicate this illness is for food handlers to practice proper hygiene procedures. As norovirus thrives in the intestines, fecal matter is the biggest vehicle for transmission. Improper hand washing after using the toilet or after changing diapers can increase the chance for spread of contagion. Likewise, not cleaning or properly cooking food to its recommended internal temperature is a factor that can lead to a spread of the virus.

There is almost a seasonal occurrence for norovirus, and this could be linked to ripe breeding times for norovirus in produce. Items such as cut melon and prepared potatoes can be affected. The same can be said of most varieties of shellfish, with oysters, particularly those from warmer, southern waters, among the leaders of viral carriers. Raw oysters that are a treat to many adults provide the perfect environment for growth of virus. And those shellfish have a habit of finding their way onto the menus of places that specialize in seafood delicacies. Places like cruise ships.

Factor in hundreds of people on each cruise that choose to eat local seafood while ashore in tropical ports-of-call, and the bloom of norovirus is staggering. 2006 saw thirty-four cases of norovirus that were investigated and documented by CDC officials; by U.S. law, any cruise line that enters U.S. ports must report any case of gastrointestinal illness. Cruise line officials are very defensive over the negative publicity that these types of outbreaks cause, and often cite the fact that day care centers and restaurants see a much higher number of such cases annually. While this may be true, it does not justify poor sanitation and hygiene procedures for food handlers aboard cruise ships whose fares range from hundreds to thousands of dollars per passenger. Not that there should be any less focus on domestic eateries and childcare facilities, but as the cruise industry is a high profile sector, it attracts more attention.

Still, with only thirty-four cases reported last year aboard ships, the number is only a drop in the bucket. Annually, norovirus is believed to be the cause of over 23 million cases of acute gastroenteritis. Most of them contracted from eating establishments. Among that statistic, more than seventy-five percent of the cases began in single unit restaurants or small franchise operations whose food safety and sanitation-training programs are minimal. However, small businesses that specialize in the preparation of food are not the only places where norovirus can start. Consider that in the past few months there have been outbreaks reported in the Hilton Washington Dulles Airport Hotel and in several New Hampshire nursing facilities. Over two hundred people were struck with the virus in those cases, and these establishments have stringent safety programs in place.

So, if these places all employ exacting standards, how did over 200 people come to contract the illness? It all points back to personal hygiene. If only one person encounters vomit or fecal matter that is contaminated with the virus, and that person is not painstaking in their avoidance of the potential for viral infection, the situation can get out of hand very quickly. The FDA, the CDC, and the restaurant industry-led National Restaurant Association Educational Foundation (the NRAEF) all have guidelines in place to prevent the growth and spread of viruses and bacteria that could mitigate a food borne illness. The common denominator in all of these guidelines is that those individuals that encounter the virus should wash their hands thoroughly. Too, areas that have come into contact with or are believed to have been contaminated by any pathogen should be thoroughly sanitized and/or isolated. This can include the removal and sterilization of everything from linens to clothing to furnishings. Further, anyone suspecting that they have been infected should be removed from food handling duties and areas until three days after symptoms have subsided. Even then, the person should be examined and cleared by a medical professional. In the cases of the Hilton facility and the New Hampshire nursing homes, no one individual has been identified as the source of the outbreak, but speculation runs high that a lax employee was at fault. These establishments have stringent safety and sanitation programs in place, but the responsibility to adhere to them rests firmly with every employee; one careless or unconcerned can endanger hundreds, even thousands of people.

Obviously, your personal safety is best ensured if you take certain precautions. When eating shellfish, inquire with the manager of your favorite seafood establishment as to whether the shellfish vendor that the restaurant uses is a reputable and certified one. Even then, it is a good idea to have, at least, your shellfish steamed to remove the possibility of eating contaminated food. Further, to guarantee that food service workers are exercising proper hygiene, should you suspect that someone has not washed their hands, politely ask them to do so. (Recent studies conducted by Aaron Margolin, professor of microbiology at the University of New Hampshire and director of UNH's Virus and Waterborne Disease Laboratory, have shown that over seventy-five percent of men and over fifty percent of women do not wash their hands after using the toilet.) The employee should have no problem with the request, and if the employee does, then it might be time to consider taking your business elsewhere.
Prudence and precaution may not be second nature to most folks when dining out, but a little prevention, after all, is worth a pound of cure. And even though there are no known strains of fatal norovirus, the illness can be very unpleasant. It is better to be safe than sorry. Be careful.