331 - Parainfluenza Viral Disease

Abstract

Human parainfluenza viruses are important causes of a wide spectrum of respiratory illnesses, including the common cold, otitis media, croup, bronchiolitis, and pneumonia. Four viral serotypes exist, called type 1 through type 4 human parainfluenza virus. In young children, infection often occurs in the first year of life; later, all four types of human parainfluenza virus may cause initial and repeated respiratory infections, most commonly in children in years 2 to 5 but also throughout adulthood. Infection of young children with type 3 human parainfluenza virus tends to present as undifferentiated febrile illness, bronchiolitis, or pneumonia. Infections with type 1 and type 2 human parainfluenza viruses tend to present as croup—an illness characterized by a croupy, barking cough; inspiratory stridor; and respiratory distress. Reinfections are generally less severe and typically present as a common cold with rhinorrhea. However, infections with human parainfluenza virus may be severe among immunocompromised hosts, such as patients with a malignancy or after organ or stem cell transplantation. Diagnosis of human parainfluenza virus infection is best made by reverse transcription–polymerase chain reaction of respiratory tract secretions. Therapy of childhood croup is with oral dexamethasone, given as a one-time dose to reduce the need for hospitalization and intubation. Specific antiviral medications and preventive vaccines for human parainfluenza virus infection are under investigation. Less specific, supportive measures such as aerosolized ribavirin and intravenous immunoglobulin infusion may be considered for severe human parainfluenza virus infection in immunocompromised patients.