Croup, also known as laryngotracheobronchitis, is a common childhood illness that causes swelling in the upper airway, leading to a distinctive cough. The virus responsible for COVID-19, SARS-CoV-2, has been definitively linked to cases of croup. While earlier variants were associated with lower respiratory tract issues, the Omicron variant showed a greater tendency to affect the upper airways, especially in young children. This shift resulted in an increase in croup diagnoses coinciding with Omicron surges. A child’s unique airway anatomy makes them particularly susceptible to the effects of this upper airway inflammation.
Understanding Viral Croup
Croup is an infection that causes inflammation and swelling of the voice box (larynx) and windpipe (trachea). This swelling narrows the airway just below the vocal cords, known as the subglottic region. The resulting obstruction produces the characteristic symptoms of the illness.
The most frequent cause of croup is a viral infection, with parainfluenza viruses being the most common culprits. Other typical viruses include respiratory syncytial virus (RSV) and adenovirus. Croup symptoms often begin with signs of a typical cold, such as a low-grade fever and runny nose, before the hallmark symptoms appear. The inflamed airway produces a harsh, brassy cough often described as sounding like a seal’s bark, along with a hoarse voice.
The Mechanism of COVID-19-Induced Croup
The link between COVID-19 and croup is due to the Omicron variant’s propensity for replication in the upper respiratory tract, unlike previous variants that targeted the lower lungs. When SARS-CoV-2 infects the cells lining the upper airway, it triggers an inflammatory response. This inflammation causes the tissues in the larynx and trachea to swell, particularly in the narrow subglottic area of a child’s airway. Because a child’s windpipe is smaller, even modest swelling can restrict airflow. This mechanical obstruction causes the seal-like cough and noisy breathing that defines croup.
Recognizing Severity and Warning Signs
Assessing the severity of croup involves observing a child’s breathing patterns. Mild croup is characterized by an occasional barking cough and hoarseness, with breathing that remains mostly normal. A key indicator of more severe illness is stridor, a high-pitched, harsh sound heard when the child breathes in.
Stridor audible only when a child is crying or active suggests a milder case. However, stridor present when the child is calm and at rest signifies a moderate to severe airway obstruction. Another sign of breathing difficulty is retractions, where the skin between the ribs or at the base of the neck visibly sucks inward with each breath. These retractions indicate the child is using extra muscles to pull air into the lungs. Severe croup is a medical emergency and may also be accompanied by agitation, fatigue, or an unusually fast breathing rate.
Managing Croup and Seeking Care
For mild cases of croup, home strategies can provide comfort and relief. Keeping the child calm is important because crying can worsen the cough and increase airway swelling. Exposure to cool, moist air, such as from a cool-mist humidifier or by briefly stepping outside, can help soothe the irritated airway. Ensuring the child stays well-hydrated by encouraging plenty of fluids is also necessary.
Seek immediate medical attention if a child shows signs of worsening or severe croup. This includes stridor that persists even when the child is resting, struggling to breathe, showing significant retractions, or appearing lethargic. Discoloration of the lips or face (blue or dusky) is an emergency sign indicating dangerously low oxygen levels. Because COVID-19 can cause a more severe form of croup, testing for SARS-CoV-2 should be considered to guide appropriate medical response and isolation procedures.