Norovirus is difficult to diagnose definitively. The test that can confirm the virus is costly and time consuming, Payne said, so there have not been good data on how many children are affected by it each year.
To get a better idea of how prevalent this infection really is, the researchers collected samples from hospitals, emergency departments and outpatient clinics from children under 5 years old who had acute gastrointestinal symptoms. The children were from three U.S. counties: Monroe County, N.Y.; Davidson County, Tenn.; and Hamilton County, Ohio. The samples were collected in 2009 and 2010, and were tested for both norovirus and rotavirus.
Norovirus was detected in 21 percent of children under 5 in 2009 and 2010. Rotavirus was found in 12 percent of children in the same age group. Norovirus was also found in 4 percent of healthy children tested in 2009 .
The study authors estimated that nationally, these data would mean that 14,000 youngsters under 5 would be hospitalized each year because of norovirus, and another 281,000 would visit the emergency room. About 627,000 young children would visit their doctor due to norovirus, according to the study. The cost of all of this medical care would exceed $273 million a year.
"This study doesn't mean that norovirus is increasing, only that proportionately, norovirus is responsible for more of the gastrointestinal illnesses out there," said Dr. Kenneth Bromberg, chairman of pediatrics and director of the Vaccine Research Center at Brooklyn Hospital Center, in New York City.
"This is the virus that's so contagious that when you flush your toilet, it flies all over the room," said Bromberg, who said these findings may even be an underrepresentation of the actual number of children sickened by this virus. He said because norovirus is so contagious, it's likely many of their parents were sickened a
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