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Bronchiolitis due to human respiratory syncytial virus (HRSV)

Bronquiolitis aguda Vall d´Hebron

Bronchiolitis is an infection that causes the small respiratory passages in the lungs (bronchioles) to become inflamed and mucus to build up in them. This blocks the flow of air, making it difficult to breathe.

It happens more often in babies because their airways are smaller and more easily blocked than in older children.

Bronchiolitis is not the same as bronchitis, which is an infection in the larger and more central airways that typically causes problems in adults.


Human respiratory syncytial virus (HRSV) is the most common cause of lower respiratory tract infection in babies and small children and it is one of the viruses that causes fever in children.

When it infects the lungs and airways, it is often responsible for bronchiolitis and lung disease or pneumonia in children less than one year old. In fact, the highest incidence of HRSV occurs in babies from two to eight months old.

It occurs more often between the months of October and March. 

Human respiratory syncytial virus (HRSV) is also the most common cause of hospital admission in babies under one.


Signs and symptoms

Bronchiolitis often begins with the same signs as catarrh. Infection can stay in the nose or extend to the ears and lower respiratory tracts.

Babies and small children affected by HRSV may show signs of:

  • Coughing
  • Fever
  • Blocked or runny nose
  • Tiredness when feeding or loss of appetite
  • Signs of breathing difficulty:
  • Breathing irregular, fast, and shallow
  • Nostrils widen and muscles under ribs contract (pull) to get more air in and out of lungs
  • On breathing, they may complain and squeeze tummy muscles
  • They will make a high-pitched, hissing sound - wheezing - as they exhale.
  • If they find it hard to breathe, you may notice a bluish tint around their lips and on their fingertips



Treatment for bronchiolitis due to HRSV basically consists of alleviating the symptoms. Antibiotics, which treat bacteria, are useless because, as we mentioned above, it is caused by a virus.                                                   

It is therefore advisable to:

  • Keep the child semi-upright in bed so that secretions do not build up and they can breathe better.
  • Maintain good hydration (drink plenty of fluids) so they do not get dehydrated and secretions are very fluid.
  • Carry out nasal decongestion with a nasal aspirator or nasal drops with a mild saline solution, especially before meals.
  • Split feedings, offering less volume, but more often, so that the child does not get tired.
  • It is essential to keep breastfeeding because of its protective effect.

Severe cases are treated in the hospital to give humidified oxygen and medication to help the child breathe more easily. In total, the condition usually lasts between one week and ten days, although a residual cough may persist for weeks. Bear in mind that the virus does not give the child immunity; they can become infected twice in the same season and reinfected in subsequent years.



Human respiratory syncytial virus (HRSV) is very contagious. It is spread if you come into direct contact with the nasal and throat secretions of someone who has the disease. This can happen when another child or adult coughs or sneezes nearby and the tiny droplets are inhaled by the baby. Also through hands or objects that have come into contact with infected people and then come into contact with the baby.

The virus can live for half an hour or more on your hands. It can also live for up to five hours on clothing, tissues, toys or furniture. 

Infection can be prevented using several measures:

  • Wash your hands often before touching the child.
  • Avoid close contact with people with symptoms of respiratory illness or fever with other sick babies.
  • Cover your nose and mouth when you cough or sneeze.
  • Clean and disinfect surfaces and objects that have come into contact with infected persons.
  • Use hygiene material exclusively for the child.
  • Keep the house well ventilated.
  • If the child is sick, they should stop attending nursery for at least a week, as it is a source of illness.
  • Avoid enclosed, very stuffy environments or exposing babies to tobacco smoke.

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