Cases of enterovirus D68 (EV-D68), which has no known cure or vaccine, have more than doubled in the last year.
Linked to cases of very young children being left unable to walk, the virus can leave kids fighting to breathe or swallow.
The public are advised to take good hygiene precautions when sneezing and coughing, wash their hands and avoid close contact with people with colds and flu-like illnesses.
It is understood four young victims have been hospitalised in the UK, with a boy and primary-aged girl in the Edinburgh area in intensive care for more than a month.
The outbreak follows one in Wales during the winter of 2014-15.
Public Health England has now published a risk assessment stating the virus is associated with ‘polio-like’ neurological symptoms.
Last year only 14 cases of EV-D68 were detected in the UK, but this year has already seen 38 lab-confirmed infections.
Most young patients have been admitted to hospital with respiratory problems, with some suffering neurological issues.
While doctors have been notified, affected families fear too little has been done to alert the public.
One source, speaking to Mail Online, said: “There’s a real concern the spread of this virus isn’t being made public.
“GPs need to know this virus is out there so they can recognise symptoms and make quick referrals. Symptoms seem to start with a sore throat but, within a day or so, they are left unable to breathe as their muscles stop working and they become floppy.
“It’s a terrifying disease that leaves a lot of the children permanently paralysed. Health officials seem to be really keen this is kept secret but parents and doctors need to know.”
NHS Lothian incident management team chair Dr Kate Templeton confirmed: “We have been investigating a possible cluster of patients infected with enterovirus D68. The patients are all now testing negative for the virus.”
EV-D68 is linked to a phenomenon called acute flaccid paralysis that causes patients’ muscles to rapidly weaken.
If the muscles needed to breathe fail, patients can die.
Children are more vulnerable because they have not built up immunity to such viruses.
An outbreak of EV-D68 in the US killed 14 people and infected 1,153 between August 2014 and January last year. Public Health England has confirmed the virus is circulating but said cases are in line with expected numbers.
Many people who contract the virus only ever have mild cold-like symptoms and do not suffer paralysis.
The public are advised to take good hygiene precautions to minimise the risk of infection.