Pupils have been told to stay home and work online and a Christmas concert was cancelled after rats swarmed their school.
Originally bosses at Conwy Council said the building at Ysgol Eirias would remain open, with certain classrooms closing while a pest control experts tackled the problem.
But NorthWalesLive r eports how pupils had been told to work online at home because of "new developments".
Announcing the move to online learning, a letter from the school said: "This is due to new developments learned this afternoon which suggest that isolation may be potentially difficult.
"Despite very limited additional new activity, the school will take no risks until all the details are firmly established."
The school's Christmas concert, which had been expected to happen on Thursday evening, was also cancelled.
The letter said: "The school will be working with the local authority in order to assess risk and plan appropriate actions."
A worried parent claimed the rats had been seen living in "papier-mâché volcanos" and abandoned toilets at the school.
Rats are known to carry numerous harmful diseases, including the hantavirus, leptospirosis, rat bite fever, rat tapeworm, and salmonellosis.
Weil's disease, a form of leptospirosis, can be contracted from the urine of infected rats.
The bacteria can enter the human body through cuts and scratches or through the mouth, eyes, and throat after contact with infected rat urine.
Whilst Weil's disease is rare in the UK, without treatment, the disease can lead to kidney damage, liver failure, meningitis, respiratory failure, and occasionally death.
Two species of rat are found in the UK, the most common being Rattus Norvegicus, otherwise known as the brown rat or common rat.
The other species is Rattus Rattus, often referred to as the black rat or the ship rat, which is much rarer in Britain.
The Mirror reported last month Prisoners in a run-down jail are living in fear of giant rats which come up through the toilets.
Last month The Mirror reported how inmates at HMP Wymott, a prison in Lancashire, had to deal with an infestation of the foot-long rodents when they nipped to the communal loos.
Those using toilets on the A-Wing were most in danger of being surprised by rats, some of which are over 1ft-long from nose to tail.
A report into the prison stated that the rats 'come up' through damaged toilets - peeking their heads up as lags go to the loo.
The report by inspectors from the Independent Monitoring Board (IMB) stated: "There was an infestation of rats in two of the toilets on A wing.
"And, in August rats were seen again, coming through damaged toilets."
