Respiratory Syncytial Virus Bronchiolitis

Respiratory syncytial virus bronchiolitis is a viral infection that affects the smallest airways in the lungs of infants and young children, often turning what seems like a simple cold into a serious breathing problem requiring urgent medical attention.

Table of contents

• What is respiratory syncytial virus bronchiolitis?
• What causes this condition?
• Signs and symptoms
• Who is at higher risk?
• How doctors diagnose this condition
• Treatment and care
• Prevention

What is respiratory syncytial virus bronchiolitis?

Bronchiolitis is a common lung infection that occurs in infants and young children under the age of two years. It causes inflammation and swelling in the smallest airways of the lungs, called bronchioles. When these tiny tubes become infected and inflamed, they fill with mucus and make breathing difficult^[1].

Respiratory syncytial virus, known as RSV, is the most common cause of bronchiolitis. In fact, RSV causes between 45% and 90% of all bronchiolitis cases^[1][2]. Almost all children get infected with RSV at least once by the time they turn two years old^[3][2].

Most children with RSV bronchiolitis have mild illness and recover at home within one to two weeks. However, some infants develop severe breathing problems that require hospital care^[2][4].

What causes this condition?

RSV bronchiolitis happens when the respiratory syncytial virus infects the cells lining the small airways deep inside the lungs. The virus causes these cells to die and break apart. The dead cells and thick mucus then clog the bronchioles, which are the tiny breathing tubes that carry air in and out of the lungs^[2][4].

This blockage leads to two main problems: some parts of the lung become over-inflated with trapped air, while other parts collapse because air cannot reach them. The result is difficulty breathing and the characteristic wheezing sound that doctors hear when listening to the child’s chest^[2].

RSV spreads very easily from person to person. A child can catch the virus through close contact with an infected person, by breathing in droplets when someone coughs or sneezes, or by touching surfaces that have the virus on them and then touching their eyes, mouth, or nose^[3][2]. The virus can survive on hard surfaces like toys and furniture for several hours^[6].

RSV infections typically occur during autumn and winter months, with the highest number of cases usually happening between December and March in the United States^[2][3].

Signs and symptoms

Children with RSV bronchiolitis typically start with symptoms that look like a common cold. For the first two to four days, the child may have a runny nose, congestion, cough, and sometimes fever^[2][1].

After these initial symptoms, the infection can move deeper into the lungs, causing lower respiratory symptoms. At this stage, parents may notice their child developing^[1][2]:

• Wheezing, which is a high-pitched whistling or purring sound when breathing, especially when breathing out
• Rapid breathing, with the child taking more than 40 breaths per minute
• Working hard to breathe, with visible effort to push air in and out
• Increased coughing, sometimes bringing up very sticky mucus

In very young infants, especially those under six months old, the symptoms may look different. These babies might be unusually fussy or irritable, less active than normal, eat or drink much less than usual, or have pauses in breathing^[1].

Some warning signs mean a child needs emergency medical care right away. Parents should seek immediate help if their child shows^[1][6]:

• Severe trouble breathing or struggling for each breath
• Bluish color on the lips, face, or fingertips
• Chest muscles and skin pulling inward with each breath (called retractions)
• Nostrils flaring or spreading out when breathing
• Short, shallow, or very fast breathing, or pauses in breathing

Who is at higher risk?

While any infant or young child can develop RSV bronchiolitis, certain children face a much higher risk of severe illness that requires hospitalization^[2][4]:

• Infants under three months of age, with the highest hospitalization rates occurring in the first 90 days of life
• Babies born prematurely, especially those born before 32 to 34 weeks of pregnancy
• Children with chronic lung disease, such as those who had lung problems from being born very early
• Children with heart disease, particularly those born with heart defects
• Children with weakened immune systems
• Children with neuromuscular disorders (conditions affecting nerves and muscles), especially if they have difficulty swallowing or clearing mucus

In the United States, about 2% to 3% of infants younger than 12 months require hospitalization for RSV infection each year. This represents more than 58,000 to 80,000 hospitalizations annually in children under five years old^[2].

How doctors diagnose this condition

Doctors can usually diagnose bronchiolitis by listening carefully to the child’s symptoms and examining the child. During the physical exam, the doctor uses a stethoscope (a medical tool for listening to sounds inside the body) to listen to the child’s lungs and check for wheezing or other abnormal breathing sounds^[2][10].

Bronchiolitis is considered a clinical diagnosis, which means doctors can identify it based on symptoms and physical findings without needing laboratory tests. Current medical guidelines state that routine testing is not necessary for most children with suspected RSV bronchiolitis^[2].

However, in certain situations, doctors may order additional tests^[10][2]:

• A nasal swab to test for RSV or other viruses. A healthcare provider gently inserts a soft-tipped stick into the child’s nose to collect a mucus sample
• A chest X-ray to check for pneumonia or other complications
• Blood tests to measure oxygen levels in the bloodstream or check for signs of infection
• Tests to check if the child is dehydrated from not drinking enough fluids

These tests are more likely to be done if the child is at high risk for severe illness, if symptoms are getting worse, or if the doctor thinks there might be another problem causing the symptoms^[10].

Treatment and care

There is no specific medicine that kills the RSV virus. Treatment for RSV bronchiolitis focuses on supportive care, which means helping the child stay comfortable and supporting their body while it fights off the infection^[2][10].

For children who can be cared for at home, treatment includes^[10][12]:

• Offering plenty of fluids to prevent dehydration (not having enough water in the body). Babies should continue breastfeeding or taking their usual formula
• Using a cool mist humidifier to help keep the air moist and ease breathing
• Suctioning the nose with a bulb syringe and saline drops to clear mucus and help the child breathe and feed better
• Keeping the child’s head slightly elevated during sleep
• Giving fever-reducing medicine like acetaminophen if recommended by the doctor. Parents should never give aspirin to children
• Watching carefully for signs that the child is getting worse

Some children need hospital care. Doctors typically hospitalize infants who are younger than three months, were born prematurely, have heart or lung disease, show signs of severe breathing difficulty, or cannot drink enough to stay hydrated^[8].

In the hospital, treatment may include^[10][2]:

• Extra oxygen through a mask or small tubes in the nose to help maintain proper oxygen levels in the blood
• Fluids given through an intravenous line (IV, a thin tube inserted into a vein) or through a tube placed through the nose into the stomach
• Regular suctioning to remove mucus from the airways
• In rare, severe cases, mechanical ventilation using a breathing machine

Current medical guidelines recommend against routinely using several treatments that were previously common. These include bronchodilators (medicines that open airways), corticosteroids (anti-inflammatory medicines), and antibiotics (medicines that fight bacteria), because research has shown they do not help most children with RSV bronchiolitis^[2][10]. Antibiotics are only used if doctors confirm or strongly suspect a separate bacterial infection.

Most children improve with supportive care and are well enough to go home within a few days. The illness typically lasts one to two weeks, though symptoms occasionally continue longer^[10][7].

Prevention

Parents can take several steps to reduce the risk of their child getting RSV^[2]:

• Wash hands frequently and thoroughly, especially before touching or feeding the baby
• Keep the baby away from people who are sick
• Avoid crowded places during RSV season, especially with very young infants
• Clean and disinfect toys and surfaces regularly
• Do not let anyone smoke around the baby
• Keep babies who were born prematurely or have health problems away from other young children during RSV season

For children at high risk of severe RSV disease, doctors may recommend immunoprophylaxis, which means giving medicine to prevent infection. Two options are available^[2][8]:

• Palivizumab, a medicine given as a shot once a month during RSV season. This is recommended for certain high-risk infants, including those born very prematurely (before 29 weeks), infants with chronic lung disease from prematurity, and infants with certain heart problems
• A newer preventive medication available for all babies before or during their first RSV season

Additionally, pregnant women and adults over 60 can receive RSV vaccines to protect themselves and, in the case of pregnant women, help protect their newborns^[3].

Parents should discuss with their child’s doctor whether their baby would benefit from preventive treatment, especially if the baby was born early or has ongoing health problems.