Respiratory viruses in laryngeal croup of young children

Area of Science:

• Pediatric Infectious Diseases
• Virology
• Respiratory Illnesses

Background:

• Acute laryngeal croup is a common respiratory illness in children, characterized by hoarseness and inspiratory stridor.
• Identifying the specific viral etiologies of croup is crucial for understanding disease pathogenesis and guiding clinical management.

Purpose of the Study:

• To identify the viral causes of acute laryngeal croup using sensitive molecular diagnostic methods.
• To include recently identified viruses in the etiological analysis of croup.

Main Methods:

• Polymerase chain reaction (PCR) was used to test nasopharyngeal swabs from children with croup (n=144) and age/season-matched controls with wheezing illness (n=76).
• A comprehensive panel of respiratory viruses and Mycoplasma pneumoniae was analyzed, including rhinovirus, enterovirus, coronavirus, RSV, PIV, influenza A and B, human bocavirus, and human metapneumovirus.

Main Results:

• Viral infections were detected in 80% of croup patients and 71% of controls.
• Parainfluenza virus types 1 and 2 were significantly more frequent in croup cases (31% and 6%) compared to controls (4% and 0%).
• Respiratory syncytial virus (RSV) was less common in croup (15%) than in controls (28%), while rhinoviruses and enteroviruses were equally prevalent in both groups (21-25%).

Conclusions:

• Acute laryngeal croup is primarily associated with parainfluenza virus (PIV), respiratory syncytial virus (RSV), rhinovirus, and enterovirus.
• Rhinoviruses and enteroviruses were found with similar frequency in both croup and wheezing illnesses, particularly during late fall.
• These findings highlight the diverse viral landscape of pediatric croup and the importance of sensitive detection methods.