Noroviruses (NoV) are important human pathogens and a major public health threat. Noroviruses are non-enveloped, single-stranded, positive sense RNA viruses that cause acute gastroenteritis in humans (1-4). Noroviruses have been referred to as ‘cruise ship viruses’ from well-publicized cruise ship outbreaks although these outbreaks account for less than 1% of all outbreaks worldwide (5). The symptoms and illness associated with Norovirus infections is often referred to as ‘stomach flu’, despite little resemblance to the influenza virus. Noroviruses are responsible for 21 million infections and over 70,000 hospitalizations annually in the USA, and account for 10-15% of severe cases of gastroenteritis in children less than 5 years old (6). In
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The genera include Norovirus, Lagovirus, Sapovirus, and Vesivirus. Caliciviruses infect a variety of animal hosts including, bovine, ovine, murine, canine, feline, marine animals, and swine, among others (10-16). The symptoms associated with calicivirus infections can vary drastically. Aside from the Norovirus genus, symptoms of caliciviruses range from upper respiratory tract infection, lesions, stomatitis, and hemorrhagic sypmtoms (10). The Norovirus infections display acute gastroenteritis in humans but are mainly asymptomatic in animal hosts (4).
Within Norovirus, five genogroups (GI-GV) have been recognized with a more recent addition of a sixth genogroup that infects canines (GVI) (4, 17, 18). The human Noroviruses belong to GI, GII, and GIV with the majority of outbreaks worldwide caused by GII strains, especially the GII.4 genotype (4, 19, 20). To improve reporting measures, the CDC and State partners have developed the CaliciNet reporting system and they determined that 73% of norovirus outbreaks from Oct. 2009 through May 2010 were from the GII.4 genotype (21). Norovirus outbreaks can occur at any point throughout the year but have been reported to be concentrated in the winter months (22, 23). Due to the dominance of the GII.4 genotype, it appears that epidemics are occurring as result of the rapid evolution of the GII.4 genotype, possibly driven by population immunity
The genera include Norovirus, Lagovirus, Sapovirus, and Vesivirus. Caliciviruses infect a variety of animal hosts including, bovine, ovine, murine, canine, feline, marine animals, and swine, among others (10-16). The symptoms associated with calicivirus infections can vary drastically. Aside from the Norovirus genus, symptoms of caliciviruses range from upper respiratory tract infection, lesions, stomatitis, and hemorrhagic sypmtoms (10). The Norovirus infections display acute gastroenteritis in humans but are mainly asymptomatic in animal hosts (4).
Within Norovirus, five genogroups (GI-GV) have been recognized with a more recent addition of a sixth genogroup that infects canines (GVI) (4, 17, 18). The human Noroviruses belong to GI, GII, and GIV with the majority of outbreaks worldwide caused by GII strains, especially the GII.4 genotype (4, 19, 20). To improve reporting measures, the CDC and State partners have developed the CaliciNet reporting system and they determined that 73% of norovirus outbreaks from Oct. 2009 through May 2010 were from the GII.4 genotype (21). Norovirus outbreaks can occur at any point throughout the year but have been reported to be concentrated in the winter months (22, 23). Due to the dominance of the GII.4 genotype, it appears that epidemics are occurring as result of the rapid evolution of the GII.4 genotype, possibly driven by population immunity