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The mass outbreak of a highly-contagious vomiting bug has forced the closure of hospital wards and schools across the UK.
In its early stages, the annual dose of norovirus, or "winter vomiting bug" as it is commonly known, has already struck down some 750,000 people according to figures released by Britain's Health Protection Agency.
Norovirus sufferers typically experience fever, nausea, diarrhoea and vomiting lasting from one to five days.
"People should be vigilant in their hygiene and we would like to remind anyone who has typical symptoms suggestive of norovirus infection to avoid visiting friends or relatives in hospital or care homes," agency spokesman John Harris told British newspaper The Daily Telegraph.
In the first two weeks of December, 43 hospital wards across Britain have been closed to new patients following outbreaks of the rapid-spreading illness, while schools are reporting record numbers of students away "sick".