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Welcome to the first Monday Micro post for 2013. Hope you all had a lovely festive season. Here in New Zealand we are enjoying our summer holidays, unlike the UK which is currently in the midst of its ‘winter vomiting virus’ season. The agent responsible, human norovirus (HuNoV) is the leading cause of viral gastroenteritis in humans, affecting all ages, including the fit and healthy. Like the All Blacks who got a taste of HuNoV during their trip to the UK in November.

A recent press release from the UK’s Health Protection Agency (HPA) says they have had 3,877 laboratory confirmed cases of the HuNoV between July to December 2012. Last year there were 2,255 cases so that’s an increase of over 70%. In December alone, there were 99 norovirus outbreaks in hospitals in the UK. The HPA go on to explain that the numbers they report are just the tip of the iceberg as the vast majority of those affected do not see their doctor. In fact, sick people are advised to stay home so as not to infect anyone else. It is estimated that for each confirmed HuNoV case, there are 288 unreported cases. That’s over 1.1 million infections in the UK this season alone!

HuNoV refers to a group of highly infectious single-stranded RNA, non-enveloped viruses in the Caliciviridae family. HuNoV is transmitted through contaminated food or water, by person-to-person contact, or via contaminated surfaces. Outbreaks usually occur in places like hospitals, care homes, prisons and cruise ships. Infection is characterised by nausea, projectile vomiting, watery diarrhoea, and abdominal pain. Fortunately, HuNoV infection is usually self-limiting, and severe illness is rare.

H/T to Michelle Sipics via Ed Yong who tweeted a link to this article about vomiting Larry, a robot developed so that researchers can study just where HuNoV might land after someone projectile vomits. There is a great interview with Prof Ian Goodfellow of the University of Cambridge who explains a little more about HuNoV and shows some excellent shots of Larry ‘vomiting’. I love that Prof Goodfellow describes HuNoV as:

“The Ferrari of the virus field”

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When reading around the topic, oysters and berries cropped up as most commonly associated with food-borne outbreaks of HuNoV. In an article out last year in the journal Current Opinion in Virology (behind a paywall – boo!), authors Françoise Le Guyader, Robert Atmar and Jacques Le Pendu discuss why this might be for oysters [1]. For a long time it was thought that oysters accumulated HuNov through filter feeding. Instead it has been found that the same proteins the virus uses to bind to human cells enables some HuNoV strains to bind to the guts of oysters too. How convenient!

Reference:
1. Le Guyader FS, Atmar RL, Le Pendu J (2012). Transmission of viruses through shellfish: when specific ligands come into play. Curr Opin Virol. 2(1):103-10. doi: 10.1016/j.coviro.2011.10.029. (Pay-walled)