Researchers identify new vaccine opportunity to help combat dreaded stomach flu
CHAPEL HILL — Researchers at the University of North Carolina School of Public Health are suggesting a vaccine for the "stomach flu" may be possible, upon discovering that the norovirus that causes stomach flu mutates genetically, similar to the virus that causes influenza.
"One of the mysteries of medicine has been why do they keep infecting people when you'd think we'd be developing immunity," stated Lisa Lindesmith, one of the lead authors of the study, published Wednesday in the online medical journal PLoS Medicine. "What we've found is that the GII.4 arm [of the noroviruses] keeps changing. Whenever we're seeing big outbreaks of norovirus, we're also seeing genetic changes in the virus."
Noroviruses are the leading cause of viral acute gastroenteritis. They are highly contagious, often causing epidemic outbreaks in families and communities, on cruise ships, in hospitals and in assisted living facilities. The viruses are especially hard on the elderly. In 2006 19 deaths were associated with norovirus acute gastroenteritis in long-term care facilities in the United States. Often, infection can mean many miserable hours, with time lost from work, school and other activities. There is no treatment to stop the infection.
The virus, first isolated from an outbreak in an elementary school in Norwalk, Ohio, in 1968, is common worldwide. The researchers analyzed the relationship among the sequences of certain genes encoding the GII.4 norovirus strains that have been isolated over the past 20 years. They found that the virus evolved irregularly, and when new strains emerged, they often cause epidemic outbreaks.
"Noroviruses are very contagious," Lindesmith said. "It may only take one or two viral particles to become infected. Good hand washing is critical when the virus is present. A vaccine may someday have an important role, too, especially among the elderly and other people particularly vulnerable to the effects of the illness."