RSV Unravels the Mysteries. Who is Most at Risk?

A runny nose, cough, and mild fever don't necessarily indicate the first symptoms of the flu or COVID-19. It could be the respiratory syncytial virus (RSV), especially during the fall and winter months, when we see a rapid increase in cases. Although it usually causes minor respiratory infections, it can also be very dangerous.

We talk to Dr. Agnieszka Sikora-Wiórkowska, a pediatrician and family medicine specialist, about what the RSV virus actually is and who is most at risk of developing a severe form.

Bronchiolitis is an acute infectious disease of the lower respiratory tract caused by a viral infection. The most common etiologic agent is respiratory syncytial virus (RSV). RSV infects the epithelial cells lining the small airways. Infection leads to swelling, increased mucus production, and ultimately, necrosis and regeneration of these cells.

In children up to 2 years of age, viral bronchiolitis is the most common infectious disease of the lower respiratory tract.

How does infection occur in children?

Infection occurs through droplets. The primary source of infection is older siblings attending preschool or school, and less commonly, adults.

Most cases of bronchiolitis are diagnosed in the autumn and winter.

For most previously healthy children, bronchiolitis is a mild, self-limiting illness that can be effectively treated at home. Only 1–2% of children require hospitalization, and a small percentage of these develop respiratory failure.

We know that parents of young children should be most vigilant. What should they pay attention to?

The most common risk factor for hospitalization is age. Most children admitted to the hospital with bronchiolitis are under 1 year of age, and in infants under 3 months of age, the disease may present with apnea and respiratory distress. Another important risk factor for severe bronchiolitis is prematurity.

Other risk factors for a more severe course of bronchiolitis include chronic respiratory diseases, congenital heart defects, neurological diseases, immune disorders, breastfeeding for less than 2 months, attending a nursery, contact with preschool and school-age siblings, and exposure to tobacco smoke.

Doctor, what does RSV infection look like in a child?

Bronchiolitis develops approximately 5 days after exposure to the virus. The course of bronchiolitis is characteristic. Typically, mild symptoms of an upper respiratory tract infection, a runny nose, and a dry cough accompanied by a low-grade fever appear at the onset of the disease. Symptoms develop gradually, usually reaching their peak on the 3rd or 4th day of illness. The cough becomes more severe and productive, which is directly related to the appearance of thick, difficult-to-expect sputum. Symptoms are most often accompanied by shortness of breath and rapid, wheezing breathing. The child flares their nostrils, grunts, struggles while eating, and stops feeding.

How do you diagnose RSV infection? Are laboratory tests necessary?

Physical examination may reveal nasal congestion and obstruction
, cough, rapid breathing, and increased respiratory effort, as indicated by nasal flaring, grunting, and retraction of the intercostal spaces, supraclavicular fossae, and diaphragm. Auscultation reveals signs of airway obstruction, such as generalized, bilateral wheezing, rhonchi, and crackles.

Typically, a medical history and symptoms observed during a physical examination are sufficient to make a diagnosis and assess the need for hospitalization. During the visit, vital signs such as respiratory rate, heart rate, and oxygen saturation are measured.

In some cases, a chest X-ray is performed and blood is drawn for testing. A rapid respiratory syncytial virus (RSV) test can also be performed by collecting a nasal swab.

Antibiotics don't work on the virus, so how are babies suffering from RSV treated?

There is no causal treatment (antiviral). Symptomatic treatment, hydration, and oxygen therapy in the event of decreased saturation are used.

Bronchodilators are used in some cases, but the indications for such treatment vary from case to case. Inhaled or systemic glucocorticosteroids are not routinely recommended. Antibiotic therapy is used in infants with bacterial complications, such as otitis media.

All infants with bronchiolitis should be evaluated for dehydration. Rapid breathing, excessive secretions, fever, and decreased appetite contribute to dehydration.

Respiratory physiotherapy should not be used in the treatment of bronchiolitis. Infection of the endothelial cells lining the narrow airways plays a significant role in the pathogenesis of bronchiolitis. This is a diffuse process that disrupts the balance between perfusion and ventilation, and therefore kinesiotherapy does not affect its course.

Suctioning secretions from the upper respiratory tract improves patient comfort and appetite. However, vigorous suctioning can cause swelling of the nasal mucosa and worsen airway obstruction. It is wise to suction secretions before meals and when there is a large amount of secretions.

To prevent RSV infection, a monoclonal antibody directed directly against the virus is used. Indications for this treatment include only premature infants, those with bronchopulmonary dysplasia, or congenital circulatory defects that cause hemodynamic disturbances.

Therefore, it's crucial to quickly identify the cause of infection. We know what treatment looks like, and how can we protect ourselves from infection?

Due to the route of infection, preventing the spread of the infection includes avoiding sick people, large crowds, and thorough hand washing. Breastfeeding is a natural method of preventing respiratory infections. Furthermore, infants and young children should not be exposed to tobacco smoke, as the harmful substances it contains weaken the immune system.

Most infants experience mild infection and recover within about 2-3 weeks. It's important to remember that subsequent infections caused by RSV can develop.