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 caused by inflammatory casts that result from allergic diseases. In type 2 PB, mucinous casts are produced in association with congenital heart disease. PB is also associated with viral respiratory infections, particularly the influenza A (H1N1) pdm09 virus, which is the most common pathogen affecting pediatric patients. Herein, we report a case of severe type 1 PB caused by human bocavirus (HBoV)1 in a child. Multiplex polymerase chain reaction (PCR) of a nasopharyngeal swab revealed the presence of respiratory syncytial virus and human parainfluenza virus 3. However, no viruses other than HBoV1 were detected in mucus casts by real-time PCR. Consequently, we suggest that HBoV can cause PB in pediatric patients, and direct and comprehensive PCR of bronchial casts may be useful for identifying the etiologic agents.