THURSDAY, Jan. 3 (HealthDay News) -- The highly contagious norovirus, often called the stomach flu, can be passed from one person to another through contact with commonly shared items such as computer keyboards and computer mice, U.S. health officials report.
The virus, which is common in winter and is the most frequent cause of outbreaks of vomiting and diarrhea in the United States, is often contracted in schools, at work and on cruise ships.
On Thursday, the U.S. Centers for Disease Control and Prevention reported on a norovirus outbreak at a Washington, D.C., elementary school last February in which some of the victims picked up the virus from contaminated computer equipment.
"There is evidence that shared objects and surfaces help transmit disease," said Dr. Shua Chai, a CDC epidemiologist and co-author of the report, published in the Jan. 4 issue of the CDC's Morbidity and Mortality Weekly Report.
"This is the first time that we have demonstrated that keyboards and computer mice can be a source of transmission of norovirus," he added.
Of the 314 students and 66 staffers at the D.C. school, 103 came down with the illness -- 79 students and 24 staff members. To find the sources of contamination, samples were taken from various surfaces around the school. In one first-grade classroom, a computer mouse and keyboard tested positive for norovirus, according to the report.
The virus can live on surfaces for several days, Chai said. To prevent infection with the virus, people should wash their hands after using shared objects, and computer keyboards and mice should be disinfected regularly with diluted bleach, he said.
"In addition, people who are ill should stay home for one to three days after they have had their last symptom, because they continue to shed the virus and can still contaminate objects," Chai added.
One infectious disease expert said norovirus is a common infection, second only to the common cold.
"These outbreaks are extremely common, and they occur in a variety of settings," said Dr. Pascal James Imperato, distinguished service professor, chairman of the department of preventive medicine and community health, and director of the master of public health program at the State University of New York Downstate Medical Center, in New York City.
Most outbreaks are food-borne, Imperato said. "A smaller percentage are due to person-to-person contact, and an even smaller proportion are water-borne," he said. "Outbreaks in schools account for about 12 percent of all the outbreaks."
Contamination of surfaces such as computer keyboards is fairly common, Imperato added.
Norovirus causes severe vomiting and diarrhea that can last for several days. The virus is usually not serious, and most people get better without treatment. However, it can be life-threatening to infants, older people and those with weakened immune systems.
In New York City, an outbreak of norovirus has been ongoing since November. Some 500 infected people have been showing up each day at emergency rooms around the city, health department officials said.
"The best way to stop the spread of norovirus is to wash your hands regularly with soap and stay home from work or school if you are sick," Dr. Sharon Balter, director of enteric disease for the New York City Health Department's Bureau of Communicable Disease, said in a prepared statement. "Norovirus is common at this time of year and is not serious for most people, but it is important to take these steps to keep others from getting sick."
Imperato agreed. "Hand-washing remains the foundation of preventing the spread of norovirus," he said.
For more on norovirus, visit the U.S. Centers for Disease Control and Prevention.
SOURCES Shua Chai, M.D., epidemiologist, U.S. Centers for Disease Control and Prevention, Atlanta; Pascal James Imperato, M.D., distinguished service professor, and chairman, department of preventive medicine and community health, and director, master of public health program, State University of New York Downstate Medical Center, New York City; news release, New York City health department; Jan. 4, 2008, CDC's Morbidity and Mortality Weekly Report