(JAMA) - Throughout the year, but especially during the winter months, outbreaks of norovirus, commonly referred to as the "stomach flu," can occur.
Symptoms may include abdominal cramps, vomiting and diarrhea. Outbreaks often occur in closed and crowded environments like nursing homes.
A new study examined whether norovirus outbreaks were associated with increased risk of hospitalizations and death among nursing homes residents.
Tarak Trivedi, a fourth year medical student at the University of Chicago Pritzker School of Medicine and co-authors examined 308 nursing homes in Wisconsin, Pennsylvania and Oregon.
All of these homes experienced at least one norovirus outbreak between January 2009 and December of 2010.
"In nursing homes, during times of norovirus outbreak we actually had an increase of about nine percent in the rates of hospitalization as compared to non-outbreak times,” Trivedi said.
The study, released online first, is published in JAMA, Journal of the American Medical Association.
"There was an 11 percent increase in the number of deaths that were occurring in nursing homes during norovirus outbreaks as compared to all other times,” Trivedi said
Researchers also examined whether daily registered nurse hours were related to these increases.
"When we looked at nursing homes that had higher number of nurse hours per patient per day we didn't see these increased deaths during norovirus outbreaks. However, we didn't see the same association with hospitalizations,” Trivedi said.
Increased rates of both hospitalization and death were concentrated in the first and second weeks of the outbreaks, suggesting that identifying the virus early is important. For health care workers, thorough hand washing with soap and water is recommended after patient contact. This helps reduce the spread of infection.
"For health care workers who become infected with norovirus we recommend that they stay home from work and not participate in patient care for at least 48 hours until after they've actually recovered from their illness,” Trivedi said.
Nursing home residents often have other underlying health issues. Researchers say it is difficult to assess whether the outbreak is actually causing death or hospitalization or whether it is happening simultaneously during another illness.
Researchers say because diagnostic testing of sporadic illness is lacking, outbreaks may provide the best opportunities for identifying the association between norovirus and deaths.