Noroviruses spread several metres by air: study

Noroviruses, a group of viruses responsible for over 50 per cent of gastroenteritis or infectious diarrhea cases globally, can spread by air up to several metres from an infected person, a new study has warned.
The study by researchers from Universite Laval in Canada suggests that measures applied in hospitals during gastroenteritis outbreaks may be insufficient to effectively contain this kind of infection.
Gastroenteritis or infectious diarrhea is a common condition where the stomach and intestines become inflamed.
The team led by Caroline Duchaine, professor at Universite Laval's Faculty of Science and Engineering and researcher at the Quebec Heart and Lung Institute (IUCPQ) Research Centre, conducted the study at 8 hospitals and long-term care facilities affected by gastroenteritis outbreaks.

Researchers gathered air samples at a distance of 1 metre from patients, at the doors to their rooms, and at nursing stations.
Noroviruses were found in the air at six of the eight facilities studied. The viruses were detected in 54 per cent of the rooms housing patients with gastroenteritis, 38 per cent of the hallways leading to their rooms, and 50 per cent of nursing stations.

Virus concentrations ranged from 13 to 2,350 particles per cubic metre of air. A dose of 20 norovirus particles is usually enough to cause gastroenteritis.
According to Duchaine, this previously unknown mode of norovirus propagation could explain why gastroenteritis outbreaks are so hard to contain.

"The measures applied in hospital settings are only designed to limit direct contact with infected patients. In light of our results, these rules need to be reviewed to take into account the possibility of airborne transmission of noroviruses," said Duchaine.
"Use of mobile air filtration units or the wearing of respiratory protection around patients with gastroenteritis are measures worth testing," she said.
The study is published in the journal Clinical Infectious Diseases.