Molecular Changes Associated with Altered Patterns of Norovirus Outbreak Epidemics in Victoria, Australia, in 2006 to 2007

Abstract

Noroviruses (NoVs) are now considered the most common cause of outbreaks of nonbacterial gastroenteritis, but the factors which control the incidence of NoVs are poorly understood. In 2006, the pattern of NoV outbreak epidemics in Victoria, Australia, changed compared to the pattern for 2002 to 2005 and 2007. This study examined molecular correlates of the changed NoV periodicity. For the period of 2002 to 2007, 8,507 fecal specimens from 1,495 gastroenteritis outbreaks were tested for NoV by reverse transcription-PCR, and 1,018 NoV outbreaks were identified. Nucleotide sequence analysis was used to define genotypes and GII.4 variants. For 2002 to 2007, GII.4 was the predominant genotype. For the period of 2002 to 2005 and 2007, a single NoV outbreak epidemic occurred in warmer months of each year, but in 2006 two epidemics occurred in 1 year, one in colder months and one in warmer months of the year. For 2002 to 2007, four major GII.4 variants, “2002 Oxford/Farmington Hills,” “2004 Hunter,” “2006a,” and “2006b,” were identified. Each NoV outbreak epidemic was linked principally to one of these four variants, and there was a time link, a delay of 2 to 6 months, between the first detection of a GII.4 variant and the first outbreak epidemic in which it was the principal variant. The unusual 2006 pattern of outbreak epidemics can then be correlated with the appearance of two GII.4 variants within a short space of time, resulting in two outbreak epidemics in a short space of time, i.e., in the 1 year. This study provides a potentially greater ability to predict the characteristics of NoV epidemics.

Noroviruses associated with outbreaks of acute gastroenteritis in the State of Rio Grande do Sul, Brazil, 2004–2011

“…variants Asia 2003 and Hunter 2004, detected in 2004, 2005,and 2006, showed a pattern of movement similar to that which occurred in other countries[41,42], although they have been detected at low frequency. However, variants of GII.4 characterized in 2006 (Yerseke 2006a and Den Haah 2006b) accounted for 37% of all GII.4.…”

A norovirus intervariant GII.4 recombinant in Victoria, Australia, June 2016: the next epidemic variant?

“…Genotype analysis also made use of the norovirus genotyping tool [ 12 , 13 ]. Information presented on norovirus gastroenteritis outbreak periodicity during 2002 to 2015 ( Figure 1 ) and the associated GII.4 variant information ( Figure 1 , Table ) made use of sequencing information from previous studies in our laboratory [ 11 , 14 ] as well as inclusion of novel data.…”

“…It is notable that in most years an epidemic peak occurred in the latter half of the year (spring–summer in Australia). An epidemic ‘peak’ was considered to be three consecutive months of the highest number of norovirus gastroenteritis outbreaks in a calendar year, except in 2006 where there were two epidemic peaks of similar size [ 14 ]. Black arrows indicate the first detection of a new epidemic GII.4 variant (Farmington_Hills_2002, Hunter_2004, Yerseke_2006a, Den Haag_2006b, NewOrleans_2009 and Sydney_2012).…”

Viral Infections, an Overview with a Focus on Prevention of Transmission

“…Numerous community outbreaks of norovirus have been reported in restaurants, resorts, cruise ships, schools, and nursing homes (Arvelo et al, 2012;Britton et al, 2014;Kuo et al, 2009;Lai et al, 2013;Wikswo et al, 2011). The emergence of a new variant of norovirus, genogroup II, type 4 (GII.4), in Australia, Europe, and North America associated with increased acute gastroenteritis activity has been reported since 2006 (Bruggink and Marshall, 2010;Hasing et al, 2013;Kanerva et al, 2009;Yen et al, 2011).…”