A stomach bug reported to have engulfed up to 500,000 victims, is putting the NHS under massive strain.

NHS trusts, already struggling with the aftermath of the Big Freeze, have had to cancel thousands of operations and ban visitors, witnessing a sharp increase in people being admitted to hospital.

The figures claim that more than 140 hospital wards were forced to close over the weekend in an effort to contain the bug, which causes violent stomach upsets.

Dr Steve Field, chairman of the Royal College of GPs, said, “It seems incredibly serious. We know it peaks twice a year and it looks like we are in the middle of a second serious peak in a few months that could be affecting up to half a million people”.

Norovirus differ from other viruses in the respect that it hangs around and it's very difficult to get rid of. In addition, it demands a lot of cleanliness.

In January 2009, there were 46 ward closures in England caused by norovirus. Over the weekend the situation resulted in the closing of 141 wards.

Experts have augured that the cases of norovirus could witness a further rise in the coming weeks.

The trusts have risen to the scenario and are taking measures such as closing wards to new admissions and exercising strict hygiene controls.