Researchers are now working to find out what causes the condition, bronchiolitis, which is a severe lung disease.

Each year, in the UK around 20,000 infants under one have to be treated in hospital for the condition, making it the most common reason for hospital admissions in that age group.

As our understanding of RSV bronchiolitis develops, so does the likelihood of new treatments and an all-important RSV vaccine.

Professor Rosalind Smyth

The Mori poll for the medical charity Action Research found only 4% of people knew bronchiolitis affected babies and children.

One in 10 confused it with the better-known lung infection, bronchitis.

Asthma link

Researchers have studied fluid taken from the lungs of babies critically ill with bronchiolitis in intensive care units.

They discovered that babies born full-term have more inflammation in the lungs than premature babies, indicating the disease works in different ways in their lungs.

The way it affects the lungs of full-term babies is very similar to inflammation seen in the lungs of older people with asthma.

University of Liverpool researchers believe this might help to explain the link between bronchiolitis and wheezing in later childhood.

They are set to carry out further research into the condition, funded by Action Research, who have put more than £140,000 into the study.

Breathing problems

Bronchiolitis is a respiratory disease in which the lower airways in the lungs become inflamed and swollen.

Most cases are caused by Respiratory Syncytial Virus (RSV).

RSV is a highly contagious, though usually mild and harmless, virus which causes cold-like symptoms.

Almost all children will have had RSV by the time they are two.

About a third go on to develop bronchiolitis, which infects the bronchioles - the tiny air passages deep in the lungs - leading to breathing difficulties.

Around 3% of have to be treated in hospital, with 2 to 3% of those babies needing intensive care treatment. Around one in 10 of these critically ill infants will die.

Professor Rosalind Smyth, Professor of Paediatric Medicine for the department of child health, is leading the research.

Professor Smyth, who is based at Alder Hey Children's Hospital, said: "Every winter, without fail, there is a huge cohort of babies with bronchiolitis being cared for on ICU.

"But there is much that we don't know about RSV infection, not least why it causes life-threatening chest infections in some infants but trivial symptoms in others."

Protection

She added: "'We know that some babies are susceptible to developing bronchiolitis, such as pre-term infants and those with underlying diseases such as congenital heart problems.

"But why should well-nourished, vigorous and healthy babies develop it?"

"As our understanding of RSV bronchiolitis develops, so does the likelihood of new treatments and an all-important RSV vaccine.

"The development of such a vaccine, that is given to babies soon after birth, or even to mothers during pregnancy, offers the best practical solution to protecting these vulnerable infants."