Parents have been warned about a possible winter vomiting bug outbreak following suspected cases across the Fylde coast.
A number of schools have sent letters to parents, urging them not to send youngsters into class if they show signs of the norovirus, which is highly contagious, causes sickness and diarrhoea, and has no known treatment.
At least one nursery said it could be forced to shut its doors if the bug spreads to staff, while community organisations such as junior football clubs and dance groups have also issued alerts.
Although reports of a widespread outbreak were played down, with both Blackpool Council and Lancashire County Council saying they had not been alerted to a surge in cases, some schools said they have noted unusually high sickness rates.
Health bosses confirmed they aware of "pockets of norovirus" due to the number of youngsters seeking urgent treatment.
Neil Hartley-Smith, a resort GP who is also a clinical director for NHS Blackpool and NHS Fylde and Wyre Clinical Commissioning Groups (CCGs), said: “Due to a number of young people being taken to the urgent treatment centres on the Fylde Coast, we are aware of some pockets of norovirus in the area.
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“We would strongly urge anyone suffering from this condition to remain at home and wait for the symptoms to pass. This is a highly contagious illness for which there is no medical treatment available.
“If you or your child is suffering from the bug, drink lots of fluids and take paracetamol to ease any discomfort. Symptoms should pass within two days.
“If you are particularly concerned about the symptoms you or your loved one is experiencing, please call 111 for advice.”
Graeme Dow, headteacher at Anchorsholme Academy, said staff have noticed "a number of pupil absences in the last two weeks", like "many" other schools on the Fylde coast, though he said they had been unable to confirm whether they are linked to the bug, which also causes nausea, a fever, a headache, and aching arms and legs.
And Graham Warnock, headteacher at St George's in Marton, said more pupils were off than normal today but added: "However, I couldn't say for sure if this is linked to the norovirus. Apart from today, absence rates have followed a normal pattern, so currently it is not a problem."
Karen McCarter, headteacher at Norbreck Primary Academy, said: "We have only had two parents ring to say their child has norovirus, and that is just parental opinion.
"So here at Norbreck, no outbreak and no letters sent home... yet."
Julie Allison, headteacher at Thames Primary Academy in South Shore, added: "We haven't had any notable increase in the number of children off with sickness and therefore haven't sent any letters home warning parents about the norovirus.
"We will continue to monitor and act accordingly should the need arise."
St John Vianney's Catholic Primary School in Blackpool shared a norovirus guide for schools on its website.
It contains tips on how to prevent the spread of the virus, and a print-out to give to parents. It said: "There is no cure for norovirus, so it has to be left to run its course. The symptoms are unpleasant and can initially be quite disturbing, but they shouldn't last for more than a couple of days.
"Adults and children with norovirus symptoms should avoid visiting GP surgeries or hospitals to prevent the further spread of the virus.
"Because the virus is highly contagious, children who have symptoms must remain off school or nursery for 48 hours after the last episode of vomiting or diarrhoea to stop the spread of the infection to other children and staff."
The school did not respond to a request for comment.
St Teresa's Catholic Primary School in Cleveleys said it had noted a "greater level of absence than expected for this time of year" in a newsletter sent to parents on Friday.
Though it did not state the cause, it thanked parents for "following guidance issued by Public Health England".
It added: "It has been key this year to protect the well-being of all our community to make sure that children have been symptom-free when returning to school."
Around 60 schools in the north east have been hit by a suspected outbreak of norovirus, it has been reported, with some schools forced to close to undergo a 'deep clean'.
Nationally, infection rates are around 26 per cent higher than they usually are at this time of year, Public Health England data suggested.
Three hospital wards in the north west have been been closed as a result, though the department was unable to provide figures for Lancashire.
Blackpool Victoria Hospital has not been affected, a spokesman there told The Gazette.