In London last week there were no paediatric intensive care beds available for a time because so many babies with bronchiolitis had been admitted. At Whipps Cross Hospital all routine surgery on children was cancelled for 10 days because the children's ward was permanently full.
Hospitals in Manchester, Liverpool, Bristol, and Cardiff are also under pressure. A combination of mild weather and poor air quality in recent weeks is being blamed for the crisis and spread of the highly infectious illness.
Babies under six months, premature infants and those with heart problems, or cystic fibrosis are most vulnerable to infection with respiratory syncytial virus (RSV), the cause of most cases of bronchiolitis. Some doctors believe that exposure to RSV sensitises the lungs so that the child is at greater risk of asthma in childhood.
The virus causes inflammation of the tiny tubes in the lungs which become blocked with mucus. The worst affected babies stop breathing altogether and need to be hospitalised and ventilated; others develop pneumonia-like symptoms, and some may need oxygentherapy. Older children tend to become wheezy but otherwise cope well with infection.
The infection is seasonal with cases peaking in winter months but many hospitals say they are seeing many more children than is usual at this time of year. Dr Robert Tasker, a consultant in paediatric intensive care at the Hospital for Sick Children, Great Ormond Street, said "four or five" times more babies had been admitted. "There are few beds for ICU in London. We've been refusing a number of cases of RSV."
Dr Vivienne van Someren, a consultant paediatrician at the Royal Free Hospital said yesterday: "We always expect a peak but it feels worse than usual at the moment."
Dr Alan Goodwin, a consultant paediatrician in Carmarthen, West Wales, with a special interest in bronchiolitis, said that he would expect to see 50-60 children every winter, but there were going to be more this year. "We are having quite an epidemic of acute bronchiolitis. Beds are filling up so quickly that other sick children are not getting admitted."
About 10 per cent of all babies develop bronchiolitis in their first year - about 50,000 - and an estimated 10,000 of them may need to be hospitalised. Most make a good recovery, but there is a mortality rate of about 1 per cent among frail babies. Others suffer recurrent infections and wheeziness in childhood.
Bronchiolitis begins with a runny nose and cough, developing into a fever with rapid breathing and difficulty in feeding. Any young baby who develops shallow, wheezey breathing and can no longer suck should be seen by a doctor, especially if symptoms develop at night. In severe cases babies develop a blueish-tinged complexion because of lack of oxygen.