The flu may be getting a late start this year, but we haven't escaped virus-induced misery. Noroviruses, which cause gastrointestinal illness, appear to be more widespread and severe than usual this winter, federal health officials say.
For those who've succumbed, no explanation is necessary.
Those who haven't are lucky.
Noroviruses -- actually a group of about 40 strains of virus -- cause intense vomiting, diarrhea, abdominal cramps, headache and fever. Although the symptoms usually last only a day or two, some cases can lead to dehydration and hospitalization. The viruses, which are highly contagious and spread swiftly in close quarters, are well known for causing outbreaks on cruise ships.
But this year, outbreaks have also been seen in nursing homes, hospitals, schools, day-care centers, restaurants, hotels and other community settings.
An outbreak involving about 500 inmates and staff members in late December temporarily closed San Quentin prison to new inmates and visitors. Another recently forced the temporary closure of a Hilton hotel in Herndon, Va., where 100 guests fell ill. Still other serious outbreaks have been reported in a nursing home in Sonoma County, where 19 residents became sick, and on the luxury liner QE2, which docked in San Francisco last week with 300 passengers and crew members recovering from the virus.
Although Los Angeles County health officials say the number of outbreaks is running about the same as last year, federal health authorities say cases of the illness are up nationwide, based on informal reports from state health departments.
"We think this year does seem to be worse than previous years," says epidemiologist Marc-Alain Widdowson of the Centers for Disease Control and Prevention. "One of the reasons may be that there is a new strain that is more easily transmitted or that people are more susceptible to."
During a typical year, noroviruses cause about 23 million infections in the United States, with 50,000 hospitalizations and more than 300 deaths, according to the National Institute of Allergy and Infectious Diseases. But a surge similar to this year's was reported during the winter of 2002-03 -- an increase that was ultimately blamed on a new strain.
That outbreak and this year's suggest that the viruses may not be as innocuous as once thought, Widdowson says. Although most people are sick for a couple of days and recover on their own, others are unable to eat or drink for several days and can become dehydrated.
"We're moving away from this idea that norovirus is mild and short-lived," says Widdowson. "It can be quite severe. You shouldn't just brush it off."
Some people, particularly the elderly and people with other illnesses, can remain sick for up to a week, he says. About 10% of people stricken with noroviruses seek medical attention for complications such as dehydration.
"Anyone who feels they can't keep fluids down and keep hydrated needs to seek medical attention," he says.
There is no vaccine or cure for norovirus, although doctors can treat accompanying dehydration and fever.
Noroviruses are nasty because of how contagious they are. The illness spreads via contaminated food or from person to person or by touching contaminated surfaces. Limiting the spread in a household, office, school or any setting requires diligence, experts say. People need to wash their hands with soap and water frequently and disinfect bathroom counters, toilets, door knobs, sinks, faucets and other areas with diluted household bleach. Disinfectants approved by the Environmental Protection Agency specifically for controlling norovirus outbreaks are also available online or from hospital supply stores.
"Vomitus is gross, obviously. But people don't think of it as being infectious," Widdowson says. "But if someone is sick in your house, that area should be disinfected afterward."
The viruses can live on surfaces for weeks, and people who have been ill can remain contagious for as long as two weeks after recovery. It's a good idea to avoid preparing food for three days after recovering from the illness, according to the CDC.
Other recommendations include quickly laundering towels, sheets and clothing that have come in contact with a sick person, says Dr. Jonathan Fielding, director of public health and the health officer for L.A. County's Department of Health Services.
Getting sick with a norovirus doesn't prevent future illness, says Widdowson. Infection with another strain is possible, and people can become reinfected with the same strain even soon after the first infection.