It has been a busy season for the “stomach flu,” that nasty, highly contagious bug that has led officials from California to Washington, D.C., to close schools, issue alerts and launch massive cleaning efforts.
The microbial culprit, norovirus, affects one in 15 Americans every year, causing sudden vomiting, diarrhea and stomach cramps that continue for a very unpleasant 24 to 48 hours, usually requiring no medical intervention.
The U.S. Centers for Disease Control and Prevention in Atlanta says about half of cases of food poisoning are caused by norovirus, which has gained infamy as the cause of outbreaks on cruise ships, college campuses, nursing homes and other gathering places.
This month, at least 85 students fell ill at George Washington University in Washington, D.C., plus 186 atRider University and about 100 at Princeton University, both in New Jersey. It also has hit hundreds of students in elementary, middle and high schools, and passengers on at least three cruise ships.
Wash hands. Passing your hands under a few sprinkles of water won’t do it. Wet hands with clean running water, hot or cold, apply soap and work into a lather. Scrub all parts of hands for 20 seconds (two rounds of the Happy Birthday song). Rinse and dry with air or a clean towel.
Avoid touching contaminated surfaces.Be aware that elevator buttons, door knobs, water fountain handles, all could potentially be contaminated.
Be careful in the kitchen. Wash fruits and vegetables, cook shellfish before eating. Don’t prepare food if you’re sick and for three days after you recover.
Alcohol gels. Their efficacy against norovirus is uncertain, but between hand-washings, they might help. They shouldn’t be a substitute for soap and water.
Clean surfaces. Use bleach-containing disinfectant wipes or a solution of 5-25 tablespoons of household bleach per gallon of water to wipe down bathrooms, kitchen and “high-touch’’ surfaces such as doorknobs, phones, light switches, hand rails.
Wash laundry. Immediately remove clothing or bedding that might be contaminated with vomit or fecal matter. Handle carefully to avoid spreading the virus. Wash in detergent at the longest cycle length and machine dry.
If you get sick, stay hydrated. Drink plenty of fluids and if you can’t, get medical help.
The best offense against norovirus illness, health officials say, is a good defense. Tips to reduce risks:
Sources: Centers for Disease Control and Prevention
“It’s everywhere,” says Jan Vinje of the CDC, who spoke about norovirus last week at a meeting of the American Association for the Advancement of Science. “Basically, January through April is high season for norovirus activity,” he says, adding with a quip: “And now it’s February — Norovirus Appreciation Month.”
Norovirus is estimated to affect more than 20 million Americans every year, causing about 800 deaths, usually a result of dehydration in the very young or the elderly.
There is no vaccine and no treatment, and if you get infected by one strain, you can get walloped by another strain, or even re-infected a few months later by the one that got you first time around. People are contagious from the moment they feel ill to at least three days — and possibly two weeks — after they recover, the CDC says.
But there’s hope. An antiviral medicine is in early development, and significant progress is being made toward a vaccine.
Charles Arntzen of Arizona State University, who also spoke at the AAAS meeting, reports that a vaccine could be ready in a few years. LigoCyte Pharmaceuticals of Bozeman, Mont., is testing its nasal spray vaccine in human volunteers, and a second research group, coordinated through ASU, is moving toward human trials of a slightly different nasal vaccine.
They’re likely to require annual booster doses because of the potential for changes in the virus or for new strains to emerge, Arntzen says.
Norovirus is a hardy bug, says Natalie Prystajecky, an environmental public health microbiologist at theUniversity of British Columbia, the third presenter at the AAAS symposium. “It can survive in cold water as long as 61 days and be infectious,” she says, and it’s detectable for two weeks on hard surfaces, though it’s not clear that it could still cause illness at that point. Cooking destroys it, but foods eaten raw, such as produce washed with contaminated water or foods prepared by cooks with unclean hands, can carry the virus.
Oysters, which are nourished by filtering water on the ocean floor, are the single food most likely to be contaminated, and many restaurants post warnings to consumers to be aware of the risk, especially the elderly, very young or those with weakened immune systems.
At George Washington University, Lynn Goldman, a physician and dean of the GW School of Public Health, says the outbreak there temporarily overwhelmed the health clinic. Crews have been called in to disinfect areas where the virus could lurk on surfaces, such as dorms, bathrooms, student lounges and study halls, and hand-washing is being promoted.
“One of the unusual things about norovirus is that one person who is ill can infect a lot of other people,” Goldman says. “As few as 18 viral particles are enough to cause infection. With many other infections, you need to be exposed to hundreds of them.”
Students on the campus of 25,000 are “taking it seriously,” she says, but “they realize that for young, healthy adults, it’s not any reason for alarm, as long as they don’t get dehydrated.”