THURSDAY, April 19, 2007 (HealthDay News) -- Rotavirus, the most common cause of severe diarrhea in children, can cause a systemic infection, not just infection confined to the intestines, a new study confirms.
The finding suggests that children may carry and pass on the bug even if they don't have diahhrea.
That's something experts have suspected for a while. "Until about three years ago, we thought the virus only infected cells in the small intestine," noted lead researcher Margaret Conner, an associate professor of molecular virology and microbiology at Baylor College of Medicine in Houston. "We thought the virus was restricted to the gastrointestinal tract."
In 2003, however, Conner's lab and others reported that rotavirus really appeared to be more of a systemic infection.
Now, Conner and her colleagues from other universities and medical centers have tested samples of blood from children hospitalized with gastroenteritis and compared them with samples from children admitted with noninfectious conditions and from healthy adults.
In all, the researchers tested blood samples obtained from children with gastroenteritis, including 57 youngsters with stools that were rotavirus-positive and 41 with rotavirus-negative stools, 58 children with bronchiolitis (a respiratory tract infection) of known viral origin, 17 with bronchiolitis of unknown viral origins, and 17 children with non-infectious conditions. They also tested 28 healthy adults.
"We looked for an antigen, a marker of whether the infectious virus is there," Conner said. The antigen is actually a protein fragment from the surface of the virus.
They found the antigen was in the blood of 51 of the 57 children with rotavirus-positive stools, in 8 of 9 in children without diarrhea but with rotavirus-positive stool, in 2 of 17 kids with bronchiolitis of unknown viral cause without gastroenteritis and in 5 of 41 children with gastroenteritis but with negative stools. The antigen was not found in the blood samples of any other group.
The findings are reported in the April issue of PloS Medicine.
The new report, Conner said, "adds strength to the idea that rotavirus is systemic." The study also shows that children who don't have diarrhea, in whom doctors wouldn't suspect rotavirus, may be infected. "It shows that even without the diarrhea symptom, kids can be infected [with rotavirus]," the researcher said.
"Our study is the first to show that even if a child does not have diarrhea, you can have rotavirus in the blood," Conner said.
In the United States, an estimated 3.5 million children become infected every year with rotavirus, Conner said. About 55,000 children are hospitalized in the U.S. each year, according to the federal Centers for Disease Control and Prevention.
The incubation period is about two days. Symptoms include vomiting and watery diarrhea for three to eight days, with fever and abdominal pain often occurring. Dehydration is a risk.
The virus is spread by the fecal-oral route. For instance, young kids who didn't properly wash their hands after toileting may play with a ball at school, contaminate it, and give the ball to another child, who may lick the ball and become infected, Conner said.
The virus gets into the intestine, replicates, and then can also escape from the intestine and go into the bloodstream, the new research shows.
Whether it will make kids sicker if it escapes into the bloodstream is not yet known, the researchers said.
Another expert called the study "extremely interesting." The advice for parents who suspect rotavirus doesn't change, even with this new information, said Mary Beth Koslap-Petraco, a certified pediatric nurse practitioner in the Suffolk County Department of Health Services for Long Island, N.Y.
"During rotavirus season, which varies in different parts of the country, parents should be careful about washing their own hands after diaper changing," she said, along with being sure young children wash their hands often.
Koslap-Petraco recommends using waterless cleaners to help kill rotavirus. A vaccine, given to infants, is also available to protect against the bug. Parents should ask their doctor about the vaccine and for details on when rotavirus is circulating in their region of the country, she said.
To learn more about rotavirus, visit the U.S. Centers for Disease Control and Prevention.