A SECOND wave of the winter vomiting bug has hit Scotland with greater ferocity this year as sub-zero temperatures continue to grip the country.

Numbers of reported cases of the norovirus bug have taken another hike as the unseasonable temperatures hold on, with the double outbreak potentially being exacerbated by cross-contamination over the holiday weekend given the large numbers of people travelling to visit friends and relatives for Easter.

An estimated one million Scots were struck down with the bug during the first wave of the infection, which was at its most potent between the end of October and mid-January. Now there are concerns there will be thousands of fresh cases in the community, mirroring the significant rise in infection rates among hospital patients.

It is believed socialising and travelling during the spring break could have re-introduced the bug to areas where it had appeared to have peaked.

Professor Hugh Pennington, emeritus professor of bacteriology at Aberdeen University, said although the link is not proven, indoor socialising brought on by bad weather is believed to help feed the virus.

He said: "The connection between the weather and the virus is that in cold weather it is more common and this is when people are spending more time indoors together.

"Socialising is the kind of thing that would cause that type of virus to linger."

He added that "normally at this point in the year we might expect the norovirus season to be coming towards an end".

With nine wards in nine Scots hospitals closed in the past week because of the bug, there are concerns of further pressures on the health service. Even during the expected winter surge – which this year began around Christmas – patients ended up waiting for beds for several hours while on trolleys in accident and emergency departments.

Overcrowding in hospitals could also be aiding the spread of the bug. Latest figures from Health Protection Scotland show 98 laboratory cases of norovirus among hospital patients during one week in mid March. Research has found that for every norovirus case confirmed by a lab there are between 239 and 346 in the community.

Dr Neil Dewhurst, president of the Royal College of Physicians of Edinburgh, warned capacity in hospitals continues to be stretched and earlier called for greater focus on the problem. Health boards insisted they are tackling the issue.

Laboratory cases of hospital patients, which is the only reliable data given that many sufferers do not seek medical help, are generally up this year compared with last.

The provisional total to the middle of March is 875. Up to the same time in 2012 health watchdogs received 756 lab reports of norovirus.

The problem is placing strain on health services across the entire UK this year, with as many as 1.89 million people said to have been hit by the virus this winter, compared with 1.79 million at the same point last year.

Norovirus is a common cause of gastroenteritis, symptoms of which include nausea, vomiting and diarrhoea. Some people may also experience fever and flu-like symptoms.

Norman Provan, associate director of RCN Scotland, said: "We've been raising our concerns for some time about the growing pressures in our hospitals and in health services out in the community. Norovirus is just one of the pressure points. What we're hearing from nurses on the frontline is that there are just not enough staff or enough beds in our hospitals or the resources in the community to cope."