Respiratory Syncytial Virus (RSV)

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Learn About RSV

The respiratory syncytial virus (RSV) is a common respiratory virus that affects people of all ages. In older children and adults it causes mostly upper respiratory symptoms (“colds”) but it can cause a serious infection in the lungs (acute bronchiolitis and/or pneumonia) among the very young infants as well as in infants and adults with serious underlying medical problems (e.g. congenital heart disease, neuromuscular disorders etc.).

Key Facts

• Almost all children will get infected by RSV during the first 2 years of age
• RSV related infections in children less than 5 years of age account for more than 2 million visits to the doctor or to the emergency room
• It is the leading cause for hospitalization for infants less than 1 year of age

What is RSV

RSV is a virus transmitted only between humans. There are two different strains (A & B) that may be causing disease of different severity. It is transmitted through infected droplets from secretions of the mouth or nose. It can survive for at least a half hour on the hands and for several hours on infected surfaces. RSV causes epidemics every year usually during the winter and early spring; however, the actual timing and the duration varies between different regions.

How it Affects Your Body

RSV can affect any part of the respiratory tract (nose, throat, larynx, the breathing tubes (bronchi)) and the rest of the lung causing intense inflammation.

The infection is most serious when it affects the small breathing tubes (bronchioles) causing what is called “acute bronchiolitis”. It can also cause pneumonia, that is an infection in the rest of the lung. Because it is often difficult to separate the two, physicians often use the term lower respiratory tract infection (LTRI). RSV is the most common cause of LTRI in infancy.

RSV bronchiolitis is causing intense inflammation inside the breathing tubes. There is irritation and swelling of the epithelium (the inside lining of the breathing tubes) and eventually destruction of its cells including those that are responsible for the clearance of mucus from the lungs. The build-up of the mucus that is mixed up with the destroyed cells “clog-up” the breathing tubes, thus making breathing difficult and preventing oxygen from getting into the alveoli (air-sacs). This decreases the amount of oxygen that enters the bloodstream and is available for the rest of the body.

The inflammation also causes spasm of the muscles that are around the breathing tubes (bronchospasm) and make breathing even harder. Because the affected infants breathe much faster and much harder than usual, they lose a lot of fluid through the lungs and can become easily dehydrated.

How Serious is RSV Infection

Most people (including infants) usually develop only mild disease similar to that of a common cold with a congested and runny nose, and some cough. About 25% to 40% of the affected infants and children will develop symptoms of bronchiolitis or pneumonia, and about 5% to 20% of them will require hospitalization, including admission to the Pediatric Intensive Care Unit (PICU). The majority of the children who require hospitalization and especially those who need admission to the PICU, are usually younger than 6 months of age. The elderly and adults with chronic heart of lung disease or with weakened immune systems are at high risk fro developing severe RSV disease if they are reinfected. Because people do not form long-lasting immunity to RSC, they can become infected repeatedly over their lifetime.

RSV Bronchiolitis: Symptoms, Causes, and Risk Factors

RSV causes a wide variety of symptoms ranging from very mild to life-threatening. The type and severity of symptoms depend on multiple factors including the particular strain of the virus and whether the patient has other underlying medical problems.

Signs & Symptoms of RSV Bronchiolitis

• Nasal congestion, runny nose, mild cough, low grade fever are typical initial symptoms of both mild and more severe forms of the disease
• Barking cough suggests significant swelling in and around the vocal cords
• Fever, either low grade (less than 101°F or ~38.3°C)** or high (more than 103°F or ~39.5°C)*

*In small prematurely born infants even a temperature above 100°F (rectally) is probably abnormal
** Very sick infants may actually have low temperature (less than 99.5°F or 37.5°C) despite warm clothes and blankets

• Difficulty breathing with one or more of the following:
  • Tachypnea (fast breathing). The respiratory rate (number of breaths per minute) varies according to the child’s age. However, when infants (even the very young ones) breathe more than 60 breaths/min it is abnormal. For patients who are tachypneic even when they are well (e.g. infants with chronic lung disease of prematurity), tachypnea is defined as 10-20 breaths above their usual respiratory rate.
  • Chest wall retractions (“caving-in” of the chest in between the ribs and under the ribs)
  • Nasal flaring (“speading-out” of the nostrils with every breath)
• Wheezing (a high-pitched whistling sound as the patient breathes-out)
• Difficulty drinking
• Lethargy or irritability
• Cyanosis (bluish color around the mouth, lips and fingernails)
• Apnea (stopping breathing) is a common symptom of RSV bronchiolitis among very young infants, especially those born prematurely

What Causes RSV?

RSV infection is caused by a virus and spreads when an infected person coughs or sneezes. The virus enters the body through the nose or mouth or very often through the eyes (when people rub their eyes with a hand that has touched infected secretions).

Risk Factors

• Crowded places with people who may be infected
• Exposure to other children (eg, in daycare) or to older siblings attending school at home

Populations at increased risk for severe disease:

• Infants less than 6 months (and especially less than 3 months) of age
• Infants born prematurely
• Infants with congenital heart disease
• Infants with neuromuscular disorders (e.g. Spinal Muscular Atrophy)
• Infants, children or adults with weakened immune system either due to a condition (e.g. primary immunodeficiency) or due to a therapy (e.g. patients who receive chemotherapy)
• People with immunodeficiency, including those with certain transplanted organs, leukemia, or HIV/AIDS
• Adults with asthma, congestive heart failure, or chronic obstructive pulmonary disease (COPD)
• Patients with Down syndrome

When to See Your Doctor

You should call your doctor if you or your child is having trouble breathing, has a poor appetite or decreased activity level, cold symptoms that become severe, or a shallow cough that continues throughout the day and night.

Diagnosing and Treating RSV infection

RSV infection is often diagnosed clinically but specific laboratory tests for the diagnosis of RSV infection do exist but in a large number of cases the diagnosis is clinical.

What to Expect

In addition to the symptoms caused by the infection itself, RSV can complicate other conditions such as asthma, COPD, etc.

How It’s Diagnosed

The mild RSV infections are usually causing problems mostly limited to the upper respiratory tract (nose, throat). The symptoms of a mild RSV infection are the same with the symptoms of a common cold and they do not require any type of testing. The diagnosis of LTRI (acute bronchiolitis/pneumonia) is usually made on the basis of the history and of the findings on physical examination. The typical cases start as an upper respiratory illness that gets worse over the next few days with increasing difficulty in breathing, wheezing and crackles in both lungs.

RSV bronchiolitis should be suspected during periods when there are outbreaks of the disease in the community. Although the illness can occur at any time, it is much more likely during the cold months of the year. However, the exact timing of the RSV season differs between different regions of the country. This information can be obtained from the Centers for Disease Control or from the local health departments.

In severe cases requiring hospitalization, specific testing for the detection of the virus is useful so the patients can be properly isolated and the infection does not spread to other patients.

There are currently several testing methods with pretty high accuracy that can give reliable results within a few hours. The testing is done on a small amount of secretions from the nose.
Patients who develop severe disease require additional tests to make sure that there are no other complications. These tests include:

1. Chest X-ray to make sure that there are no signs of pneumonia that will require treatment with antibiotics
2. Blood tests to check for signs of a bacterial infection and very importantly to make sure that the infant is properly hydrated
3. Blood and urine cultures may be necessary when the infant is very sick (in the very young infants, RSV bronchiolitis can be present with a urinary tract infection)
4. Pulse oximetry (a bandaid-like probe with a red light wrapped around the finger or toe of the infant/child) to make sure that there is enough oxygen into the blood

How It’s Treated

There is no specific therapy for RSV bronchiolitis especially at home. The basic management consists of keeping the infant comfortable, and controlling the fever with acetaminophen. Clearing the nose from secretions with the use of a bulb syringe, may improve temporarily the breathing. It is often useful to be done just before feedings so the infant can drink more easily.

Depending on the severity of illness various treatments may be tried. None of them treats the infection itself but by treating the symptoms and preventing complications they can improve the patient’s condition.

Such treatments may include one or more of the following:

• Hydration: Infants, especially the very young ones can become dehydrated very easily. At home, breast or bottle feeding should continue but they may need to be given in frequent small amounts. Inability to drink is an indication for admission to the hospital for intravenous hydration or by a feeding tube.
• Oxygen: Hypoxemia (decreased oxygen levels) is one of the typical symptoms of RSV bronchiolitis. Oxygen given through small prongs in the infant’s nostrils not only provides the necessary oxygen but decreases the work that the infant has to do for his/her breathing and prevents respiratory muscle fatigue.
• Bronchodilators, may be given either by a nebulizer or by a metered dose inhaler via a spacer in patients with significant wheezing. Certain patients benefit from the medication but others show little or no improvement. Nevertheless, the treatment is benign enough and therefore it is worth trying.
• Racemic Epinephrine: this a medication given by a nebulizer that may temporarily decrease the swelling in the airways
• Systemic Corticosteroids (Prednisone, Dexamethasone): they may decrease the inflammation but they do not change the course of the infection.
• Antibiotics do not affect the RSV infection. However, they may be necessary when there is also a bacterial infection such as otitis media (ear infection), pneumonia, or urinary tract infection.
• Ribavirin: It is the only approved specific anti-viral medication that is given via continuous nebulizations. Because giving the medication is quite cumbersome and its therapeutic benefit relatively low, it is given only to select very high risk patients.

Living with RSV

RSV is an infection from which otherwise healthy patients are expected to fully recover. However, it can be severe, life-threatening, or even fatal among high risk groups.

What to Expect

The time from exposure to the virus to the appearance of symptoms (incubation period) is between 2 to 8 days (usually 4 to 6). The acute illness lasts about 3 to 7 days. The recovery time varies depending on the severity of the acute episode and the overall health of the patient.
Patients are contagious for about 8 days. However some patients (e.g. those with weakened immune system) may be contagious for several weeks.

Prevention

RSV is highly contagious. Thus, it is extremely important to take all the necessary precautions to prevent its spread to other infants as well as to other adults.

The most effective means of protection are some of the simplest as well:

• Avoid crowded places;
• Avoid close contact (e.g. kissing) with infected people
• Avoid sharing cups, bottles or toys that may have been contaminated with the virus (it can live on surfaces for several hours)
• Thorough handwashing with soap and water for 20 sec after coming into contact with an infected person

High risk patients can receive monthly injections with the drug “Palivizumab” that prevents the development of severe RSV disease but it has no effect after the disease has started.

Long-term Effects

There is evidence associating RSV infection during the first 6 months (and especially the first 3 months) of life and the development of wheezing and asthma later in life. The exact mechanism is not known but there may be a genetic predisposition for it.

Questions to Ask Your Doctor about RSV

• Is my baby at risk for severe RSV infection?
• Is my baby a candidate for palivizumab?
• What is the duration of the “RSV season” in our city/state?
• Does my baby need any medications (e.g. bronchodilators) with “colds”?
• Is my baby allowed to drink while he/she is sick?
• Can my other children get sick too?
• Should I allow my parents kiss the baby?
• My baby was diagnosed with RSV. Can we still go to his cousin’s birthday party?
• My baby has RSV but he is not very sick. Is it OK to take him to see my mother who is being treated with chemotherapy for breast cancer?
• My baby had RSV bronchiolitis when she was 6 months old. Is she going to be an asthmatic as she grows older?

 

Author

Anastassios C. Koumbourlis, MD, MPH

Date Last Reviewed

December 2016