The relationship between health care and nonhealth care norovirus outbreak settings and norovirus genotype in Victoria, Australia, 2002–2005

Abstract

There is evidence that norovirus genotype is an important factor in determining norovirus epidemiology, but detailed information is lacking. This report examined this question by studying whether the mix of norovirus genotypes associated with norovirus outbreaks in health care settings was different to that in nonhealth care settings. Norovirus outbreaks tested in Victoria, Australia, 2002-2005 were classified as either health care or nonhealth care. Open reading frame 1 nucleotide sequencing analysis was then used to determine the mix of norovirus genotypes in health care and nonhealth care norovirus outbreaks. For the three most common genotypes detected (GI.2, GII.4, and GIIb), the differences between health care and nonhealth care settings were significant. GII.4 was significantly more common in health care settings than in nonhealth care settings, whereas the genotypes GI.2 and GIIb were significantly more common in nonhealth care settings than in health care settings. Norovirus genotype was found to be an important factor associated with norovirus outbreak setting.