The CDC's Respiratory Illnesses Data Channel, updated June 12, 2026, delivered a specific alert that most American parents have not heard about: parainfluenza virus (PIV) is elevated nationally. While influenza is low, RSV is low, and COVID-19 remains at minimal activity, parainfluenza has continued circulating at above-baseline levels — and it is making itself known through one of the most frightening sounds a parent can hear at 2 a.m.: the distinctive, harsh, barking cough of croup.
For parents who have experienced a child with croup, the description is unforgettable. For those who have not, the name "barking seal cough" captures it accurately — a harsh, resonant, metallic cough that sounds entirely unlike a standard respiratory illness cough. It is caused when parainfluenza virus infects and inflames the larynx (voice box), trachea (windpipe), and upper bronchial tubes in young children, whose airways are small enough that even modest swelling produces audible, and sometimes dangerous, breathing restriction. The narrowed airway creates the characteristic sound on inhalation called stridor — a high-pitched, musical wheeze with each breath in — that tells clinicians and experienced parents that a child's upper airway is compromised.
