Last updated at 08:12 09 January 2008

More than 3.6million workers have called in sick so far this week, a survey suggests.

A record one in eight staff has been laid low, with the winter vomiting bug, norovirus, cited as the main culprit.

Chronic coughs and colds have also seen workers take to their beds.

Health experts warn that sickness may soon reach pandemic levels with large swathes of the population being struck down.

Aaron Ross, of FirstCare, the absence management firm which produced the figures, said: "This is the worst period of sickness we have ever seen and it comes at a very bad time for employers.

"Most organisations wound down during the unusually long holiday period and they are experiencing real trouble starting up again.

"There has been a lot of press coverage surrounding the norovirus and people are being advised to stay at home for two days after the symptoms have stopped."

Norovirus - which causes uncontrollable projectile vomiting - is said to be costing the economy £ 40million a day in lost productivity.

One hundred hospital wards were closed to admissions last week in an attempt to halt the march of the virus, which is 100,000 times more infectious than salmonella.

Mr Ross said: "Wards are closed, shops and restaurants are limiting their activities, deliveries and service calls will be late.

"All of this will have a knock-on effect on those staff who are at work as they will be put under more pressure to cover absent colleagues.

"The extra stress and strain will, in turn, make these employees more susceptible to falling ill themselves."

He said that 4 per cent of the employees covered by FirstCare had called in sick on Monday with a similar pattern seen yesterday.

"This is the closest thing to a pandemic that employers will have seen for years and it should be a wake up call for businesses that don't have contingency plans for high sickness rates," he added.

The spread of norovirus can be restricted by washing hands regularly and disinfecting much-used items, such as remote controls and telephones.

Other tips include ventilating a room after someone has been sick and not sharing towels, toothbrushes or cutlery.

Norovirus symptoms last for up to three days and it is contagious for another two days or so.

The very old, very young and those already seriously ill with other ailments risk complications from dehydration.

There is no treatment other than drinking plenty of liquid.

Mr Ross said the impact of norovirus showed that firms should prepare for even more serious illnesses such as bird flu.

He claimed that some of the absenteeism could be explained by stress brought on by the cost of the festive period.

"With Christmas credit card bills round the corner and a cold winter approaching we are likely to see continued high sickness rates," he said.

"I recommend that businesses bring forward the pay day for January as well as December because it is a very long month.

"The weather also has a profound effect. It has been a mild winter so far and that is why there have been so many coughs and colds - the weather has not been able to kill them off."