n 2006, 53 family members from six states gathered at a home in West Virginia for what should have been a pleasant one-day reunion. But within a few days of the reunion, at least 28 of the attendees had come down with a combination of diarrhea, vomiting, cramps, nausea, chill, and body aches.
The culprit: norovirus.
The case — later examined by local and state health officials — underlined just how wily norovirus can be, and how quickly it can spread, particularly among people in close quarters. It also helps explain why the suspected cases involving a dozen Republican staffers in the Cleveland area for the Republican National Convention have caused such alarm.
Here’s what you need to know about norovirus:
What is norovirus?
Norovirus is the leading cause of gastroenteritis (inflammation of the stomach or intestines) in the United States, responsible for about 20 million cases each year. It is typically spread through improperly handled food or from people passing the virus to others.
Infection used to be known as winter vomiting disease.
Most people experience a quite unpleasant couple days of diarreha, vomiting, and getting to know the tiling on their bathroom floor intimately, and then recover. But it can lead to dangerous levels of dehydration.
Norovirus is a factor in a few hundred deaths a year, typically in the elderly, young children, or people with other illnesses. Deaths and hospitalizations are more common in winters, such as those in 2002-2003 and 2006-2007, when particularly harmful strains are circulating.
The virus can be found in people’s stool before they start feeling sick and can persist for a few weeks after recovery, but people are most contagious when they are showing symptoms and in the first few days after they start to feel better. The virus is easily passed in prisons and nursing homes, day care centers and schools, convention halls and restaurants.
How can I protect myself?
The best advice is to steer clear of people who are sick, wash your hands lots, disinfect contaminated surfaces, and to wash fruits and vegetables thoroughly. And if you do get sick, wash your clothes in case they are contaminated, and don’t prepare food or try to care for others who may be sick.
Why do I think cruise ships when I hear norovirus?
Yes, cruise ships face their share of norovirus outbreaks. There have been up to a dozen norovirus outbreaks on cruise ships each of the past few years, according to a database maintained by the Centers for Disease Control and Prevention.
Cruise ships are required to report cases of stomach illness to health authorities, and the CDC launches an investigation when 3 percent or more of passengers or staff come down with an illness. The agency tracks all outbreaks of gastrointestinal illnesses on cruise ships; norovirus is the guilty party in the large majority of the cases.
One famous case: Norovirus sickened almost 700 passengers and crew members on Royal Caribbean’s Explorer of the Seas in 2014, leading to reports of an overcrowded infirmary, people vomiting throughout the ship, and people being confined or confining themselves to their rooms for days.
I get seasick anyway. Am I safe from norovirus if I avoid cruises?
Not at all. Norovirus outbreaks are actually quite common, and by no means are cruise ships the sole breeding ground.
In just the past year or so, outbreaks at Chipotle restaurants sickened 243 in California and 143 in Boston; 200 people became ill after a catered event at a downtown Seattle office tower; and hundreds of people got sick at college campuses including Miami University of Ohio and Michigan State University. And those are just a few of the recent outbreaks.
Past outbreaks have occurred at an NAACP conference in California in 2014, and also that year, a possible norovirus outbreak in Colorado prisons forced officials there to restrict family visits around Easter. It was also the leading cause of stomach illness among US Marines during Operation Iraqi Freedom.
One notable outbreak in 2005 stemmed from a single bakery that made cakes for 46 weddings one weekend. At least two bakery employees showed symptoms of a norovirus illness the week leading up to the weekend of the weddings, and you can guess what happened next. Health officials didn’t get a final tally of the number of people who got sick, but wrote in a report that it could have been up to 2,700.
The officials concluded: “These findings reinforce the necessity of proper food-handling practices and of policies that discourage food handlers from working while ill.”
Ike Swetlitz and Helen Branswell contributed reporting.