Microbe of the Month: The New Norovirus
Winter Vomiting Alert: New Strain of Norovirus on the Rise
By JoNel Aleccia, Staff Writer, NBC News
A nasty new strain of norovirus, a highly contagious gut bug, has circled the globe and landed in the U.S., where it's now the leading cause of what's known indelicately as "winter vomiting disease."
Health officials at the Centers for Disease Control and Prevention said Thursday that the GII.4 Sydney strain of norovirus was responsible for more than half of outbreaks of the illness during the last four months of 2012. The new norovirus spread amid a particularly harsh flu season that's also causing misery.
Of 266 outbreaks of norovirus between September and December, 141 were caused by the bug that was first detected in Australia in March 2012, according to data from CaliciNet, which tracks norovirus outbreaks. The proportion of outbreaks caused by the new strain jumped dramatically from 19 percent in September to 58 percent in December, the CDC says in its weekly report on death and disease.
"Right now, it's too soon to tell whether the new strain of norovirus will lead to more outbreaks than in previous years. However, CDC continues to work with state partners to watch this closely and see if the strain is associated with more severe illness," said Dr. Aron Hall, a CDC epidemiologist specializing in viruses.
Like the virus that causes the flu, norovirus mutates quickly, resulting in a new strain every few years, Schaffner said. When that happens, people who've already had previous versions of the bug that can cause profuse vomiting and diarrhea are more likely to get it again. "What that means is more of us are susceptible," said Dr. William Schaffner, a infectious disease expert at Vanderbilt University in Nashville, Tenn.
That can be a particular problem in enclosed spaces, such as cruise ships, nursing homes or other gatherings where people share close quarters.
The virus spreads ridiculously easily, often carried in the air after projectile vomiting, or lingering on surfaces where it infects the next victim, Schaffner said.
"It's very contagious," he said. "It takes only a few viral particles." In addition, the general public ought to be aware that the new bug is out there and take precautions including washing hands with soap and water, disinfecting surfaces, rinsing fruits and vegetables, cooking shellfish thoroughly and not preparing food or caring for others while ill.
CDC officials said it's too early to tell whether the new strain will lead to more outbreaks or more serious illness, but they're watching the situation closely.
Facts Behind the Pains of Stomach Viruses
By Anne Harding
Ugh, what could be worse than a stomach bug? The vomiting, diarrhea, stomach cramps and more.
Despite the fact that it's so common-there are at least 20 million stomach-flu cases in the U.S each year-many people don't know much about it. For one, it's not really the flu!
Here are 13 things you need to know about viral gastroenteritis (its true medical name), starting with the fact that it's caused by viruses that attack the stomach and intestines.
A Flu Shot Won't Help
When people say "the flu" they mean influenza, a virus that circulates the globe each year, attacking the nose and throat as it spreads though communities in waves. Flu shots protect against this virus-not ones that cause viral gastroenteritis.
The confusion may be due to some symptom overlap, such as body aches, nausea and low-grade fever, says Gary Rogg, MD, an internist at Montefiore Medical Center in New York City.
But a flu shot won't protect against stomach bugs. There's no such thing as a stomach-flu shot (at least for grown-ups).
Culprit, thy name is norovirus
Stop blaming the flu and instead know the true name of your trouble: norovirus.
This is a family of viruses most often to blame for adult gastroenteritis, although others include adenovirus and astrovirus. (Rotavirus is the most common cause of viral gastroenteritis in babies and young children).
Norovirus can spread like wildfire in any crowded place, causing outbreaks in day care centers, schools, cruise ships, hospitals and nursing homes.
It's Extremely Contagious
Stomach flu spreads via the "fecal-oral route," which is just as gross as it sounds. Basically, viruses from infected feces or vomit find their way into our mouths. Very diligent hand washing is your best defense, according to Dr. Rogg.
Wash carefully if you're changing diapers or cleaning up after a sick child, and grown-ups in the household should clean up after themselves if they can, advises Dr. Ryan Madanick, a gastroenterologist and assistant professor of medicine at the University of North Carolina School of Medicine in Chapel Hill, N.C.
You Can Get It From Food
Viral gasteroenteritis isn't exactly the same thing as food poisoning, which refers to any illness caused by food contaminants, including dangerous toxin-producing bacteria like salmonella. But norovirus is the No. 1 cause of foodborne illness in the U.S.
Viral gastroenteritis can be spread from person to person or by touching a contaminated surface, but you can also get viral gastroenteritis from sewage-contaminated food or water or from meals prepared or handled by an infected person. (Hence all those "wash your hands" signs in restaurant bathrooms.)
These Germs are Tough
Compared to other viruses, noroviruses can be surprisingly hardy and live for days on household surfaces, which is why they spread easily. (That, and very few virus particles are needed to cause an infection.)
Wash your hands with soap and water, which is more effective than hand sanitizers. Avoid food prep if you're sick (you can still be infectious for three days or more after symptoms wane), and wash laundry carefully, using gloves to handle soiled clothing and bedding if you can.
Use a bleach-based cleaner to kill virus particles on hard surfaces.
Symptoms Come On Slowly
Diarrhea, vomiting, and stomach pain don't hit you immediately after you're infected with a gastrointestinal virus, but typically develop gradually, over one or two days, Dr. Madanick explains.
But other types of food poisoning can strike fast and hard-within a few hours after you're exposed to the offending substance-and symptoms tend to be more dramatic, such as explosive vomiting and diarrhea.
It Gets Better on Its Own
Both stomach flu and other types of food poisoning are what doctors call "self-limiting," meaning they play themselves out and rarely require medical treatment.
While norovirus is the leading cause of foodborne illness, germ-for-germ, salmonella and other bugs are more likely to result in hospitalization or death.
If you've got viral gastroenteritis, you should start to feel better after two or three days. While food poisoning due to other causes hits you harder and faster, it goes away faster too; you may be back to normal in a day or two.
Dehydration is the Biggest Risk
It stands to reason that if you're losing lots of fluid through watery diarrhea and vomiting, you need to replace that fluid. But you're also losing sodium, potassium, and other minerals, known as electrolytes, and they also need to be replaced.
You should drink Pedialyte, or similar oral electrolyte solutions that contain salts and sugar as well as water, if you have severe diarrhea. Sports drinks aren't a great choice, because the mix of salts and sugars they contain isn't exactly right in terms of replacing fluid lost to diarrhea and vomiting.
Water Isn't the Best Choice
Try to avoid drinking too much plain water, or beverages like soda or juice that contain sugar, but not enough of the right electrolytes, says Dr. Rogg. "The biggest mistake that people make is just trying to drink a lot of water," he adds. "They understand that they have to prevent themselves from getting dehydrated, but what they're actually doing is wrong."
Putting water into your body without adding electrolytes will dilute the electrolytes that still remain in your body, Dr. Rogg explains, while taking in sugar without salt can make your diarrhea worse.
OTC Tummy Remedies May Help
There is no treatment for viral gastroenteritis, besides time and symptom relief. (Antibiotics are useless, so don't be surprised if you don't get one from your doctor.)
Over-the-counter remedies that contain bismuth subsalicylate (like Pepto-Bismol) may help for simple diarrhea.
Antidiarrheal medications may also help ease cramps and diarrhea, but you should avoid them if you have bloody diarrhea or a high fever as it can make the illness worse, according to the Centers for Disease Control and Prevention.
When to Call Your Doctor
If you see blood in your stool or vomit, call your doctor right away. Diarrhea on its own is not a cause for alarm, but call your doctor if you also experience extreme lethargy, confusion, or otherwise altered mental status, or a lack of urine (or dark and concentrated urine), which are signs of serious dehydration.
Also get help if your symptoms aren't getting better after three days, you have prolonged vomiting that prevents liquid intake, or if you spike an oral temperature over 101.5 degrees Fahrenheit.
The Old, Young, and Sick Are At Greatest Risk
Young children's developing immune systems make it harder for them to fight off viral infections, while their smaller bodies are also at greater risk of becoming dehydrated. Elderly people are also more prone to coming down with viral gastroenteritis, and take longer to recover afterwards, Dr. Rogg says.
Anyone with a chronic illness, such as heart disease, asthma, cancer, or kidney disease, or who has HIV or is taking medications that suppress the immune system, should check with a doctor if they come down with the stomach flu.
Take It Slow on the Road to Recovery
When you stop vomiting and your diarrhea subsides, you're probably going to feel pretty hungry. But wait a few days before you celebrate with a feast, Dr. Rogg warns. "Don't eat as if you were well until you've felt fine for a couple of days," he advises. "Eat smaller meals, and drink in smaller volumes.
Basically, you'll want to avoid eating or drinking in a way that will distend the stomach." Overloading the stomach too soon may make you feel sick all over again, so skip fatty foods and stick to light, easy-to-digest meals.
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