Croup

Croup is a viral respiratory infection most common in young children, usually caused by the parainfluenza virus. It results in the inflammation of the larynx and trachea, which leads to a characteristic barking cough, hoarseness of voice, and inspiratory stridor. The diagnosis is usually clinical, but can need an x-ray for confirmation. When done, X-rays show a steeple sign, which is subglottic narrowing.