Plastic bronchitis of human bocavirus 1 detected by comprehensive polymerase chain reaction of mucus casts.

Plastic bronchitis (PB) is a rare and severe respiratory disease characterized by the formation of branching mucus casts, resulting in airway obstruction. PB can be divided into two types. Type 1 PB is primarily due to inflammatory casts caused by allergic diseases. In type 2 PB, mucinous casts are produced in association with congenital heart diseases. PB is also associated with viral respiratory infections, particularly influenza A (H1N1) pdm09 virus, which is the most common pathogen affecting pediatric patients. Herein, we report a severe case of PB type 1 caused by human bocavirus (HBoV) 1, affecting a child. Multiplex polymerase chain reaction (PCR) with a nasopharyngeal swab revealed the presence of respiratory syncytial virus and human parainfluenza virus 3.However, no viruses other than HBoV 1 were detected from mucus casts via real-time PCR. Consequently, we suggested that HBoV can cause PB in pediatric patients; direct and comprehensive PCR with bronchial casts may be useful for identifying etiologic agents.