Croup and RSV (Respiratory Syncytial Virus)

DR. Z,

What is Croup and RSV?


What is it?


Croup and RSV (Respiratory Syncytial Virus) are common childhood viral illnesses that predominate during late fall, winter, and early spring. Croup, by definition, is an upper respiratory tract infection that results in inflammation and increased mucus production in the larynx, trachea (windpipe), and bronchial tubes. It is this swelling around the vocal cords that provides the characteristic “barking cough” of croup.

RSV is another virus that causes infections of the lungs and respiratory tract. RSV is so common that most children have been infected by the age of two. For the majority of those affected, RSV causes only mild cold-like symptoms but it is also the most common cause of bronchiolitis and pneumonia among infants and children under the age of one.


What causes it?


The vast majority of upper respiratory tract infections are viral in nature. Croup is most often caused by the parainfluenza virus.

Both of these infections are highly contagious as the virus enters your body through your eyes, nose or mouth. It spreads easily through respiratory secretions such as those from coughing and sneezing or direct contact, such as shaking hands. Virus particles can survive for hours on toys, countertops, and other surfaces. If your child touches a contaminated surface and touches his or her mouth, nose, or eyes, an infection may follow.

Who gets it?


Croup most commonly affects children between the ages of six months and three years. This common viral illness is estimated to occur in 5% of children between the ages of 1-2 years and is the most common cause of stridor (upper airway wheezing when a breath is taken) in this age group. Because the symptoms of croup are caused by inflammation and swelling of the vocal cords, it makes sense that younger children with smaller airways are the ones more often affected. In contrast, older children will often develop minor cold-like symptoms because their larger breathing passages (trachea and larynx) can accommodate the inflammation without producing symptoms.

By contrast, RSV can affect people of all ages, but is much more common in children. The vast majority of infants and children have been infected by the virus by the age of two and while RSV is leading cause of pneumonia in children under one year of age, the majority of hose infected experience only mild signs and symptoms. In adults and older, healthy children, the symptoms of RSV are mild and typically mimic the common cold.

What are the signs and symptoms?

Infections of croup usually occur about two to six days after exposure. In most cases, croup begins with a cold, cough, and low-grade fever, with a relatively abrupt or sudden onset of symptoms. The distinctive barking cough is usually present by day 3 and is more likely to be worse at night. Another common symptom of croup is inspiratory stridor, which is a loud, high-pitched, harsh noise that children with croup often have when they are breathing in. This is caused by the inflammation in the larger airways and vocal cords.

Signs and symptoms of RSV infection typically appear about four to six days after exposure to the virus. In adults and children older than three, RSV usually causes mild cold-like signs and symptoms such as:

  • Congested or runny nose
  • Dry cough
  • Low grade fever
  • Sore throat
  • Mild headache
  • A general feeling of unease and discomfort (malaise)

In children younger than three, RSV can lead to more serious lower respiratory tract infections such as pneumonia and bronchiolitis (an inflammation of the small air passages entering the lungs). These signs and symptoms may include:

  • High fever
  • Severe cough
  • Wheezing (a high-pitched noise, usually heard when breathing out)
  • Rapid breathing or difficulty breathing, which may make the child want to sit up rather than lie down
  • Bluish color of the skin due to lack of oxygen

How is it diagnosed?

Both of these infections are typically diagnosed based on a physical exam and pattern of your child’s symptoms. In both cases, the doctor may listen to your child’s lungs and examine your child’s throat. In some suspected RSV cases your doctor may use:

  • Painless skin monitoring to assess the level of oxygen available in your child’s bloodstream
  • Blood tests to check white blood cell counts and/or the presence of the virus
  • Chest x-rays to check for pneumonia
  • At MY DR NOW we use a rapid RSV test to notify our patients of an RSV infection, which takes just a few minutes

How is it treated?

For the majority of croup infections, and mild RSV infections, treatment for these illnesses is self-care at home. Children with croup may benefit from breathing humidified air which is thought to help with the coughing and stridor. Taking the child outside while dressed warmly on a cold day for a few minutes may help as well. Children’s Tylenol may be given for fever and some children benefit from sitting up straight for ease of breathing. In more severe cases of croup, steroid therapy may be given to decrease any associated inflammation caused by the infection.

In mild cases of RSV, many of the same measures may apply: Children’s Tylenol for any fever, good hygiene such as hand washing and avoiding any harmful irritants such as cigarette smoke. In severe cases, hospitalization may be necessary to provide IV fluids and oxygen. Antibiotics, which doctors prescribe to treat bacterial infections, are of no use against RSV and croup because they are both viral infections. However, your doctor may prescribe antibiotics if there’s a bacterial complication, such as a middle ear infection or bacterial pneumonia.

If your child has any of the above mentioned symptoms, or if you are concerned about a potential infection, don’t hesitate to visit your local medical clinic for further evaluation and treatment.

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