Cross Ash Primary School has suffered a double blow of winter sickness with a chicken pox outbreak being followed immediately by suspected Norovirus.

There were reported to be more than 75 staff and pupils absent last week, a staggering 42 per cent of the school population.

Chicken pox is a normal childhood illness and something which hits schools regularly. The more unfortunate outbreak was the suspected Norovirus which, while not dangerous, is highly contageous and extremely disruptive. One person carrying the infection is likely to infect around 14 people.

The first sign of norovirus is usually a sudden sick feeling followed by forceful vomiting and watery diarrhoea. Some people may also have a raised temperature (over 38C/ 100.4F), headaches, stomach cramps and aching limbs.

Symptoms usually appear one to two days after you become infected but they can start sooner. Most people make a full recovery within a couple of days.

Apart from the risk of dehydration, the illness is not generally dangerous and there are usually no long-lasting effects from having norovirus. Symptoms will last for 12 to 60 hours although the patient is still infectious for 48 hours after the symptoms have ceased.

Parents on the school's Facebook forum were concerned about sending their children into school in case they became re-infected, especially those with children who had just spent the week off school with chicken pox.

Due to the highly infectious nature of norovirus, many parents and siblings not attending Cross Ash school have now been infected.

The school's headmistress, Marilyn Balkwill, had no comment to make about the incident but a spokesman for Monmouthshire County Council said: "We are able to confirm that there has been a suspected viral outbreak of Norovirus at Cross Ash school.

"The illness is not serious and many of the affected children are now back at school.

"We carried out a deep clean of the school over the weekend. There have also been a number of cases of chicken pox confirmed."

Mike Fawcett, the deputy head, sent an email to parents on Monday encouraging them to be vigilant for signs of the virus and to wait at least 48 hours after a child has presented their final symptoms before sending them back to school.

So far, there have been no other outbreaks reported in schools in the area.