What are the clinical manifestations of parainfluenza virus (PIV) pneumonia?

Updated: Mar 24, 2021
  • Author: Zab Mosenifar, MD, FACP, FCCP; Chief Editor: John J Oppenheimer, MD  more...
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Clinical manifestations of PIV infection can range from mild upper respiratory tract infections (mainly in immunocompetent patients) to severe croup, bronchiolitis, or life-threatening pneumonia in the setting of immunosuppression. Incubation is 1-3 days. The classic croup symptoms of barking cough, hoarseness, and stridor commonly seen in children is less commonly seen in adults. In adults who are immunocompromised, cough is the hallmark.

PIV-1 and PIV-2 produce croup in children that initially manifests as an upper respiratory tract infection followed by a barking cough, dyspnea, stridor, and chest-wall retractions. PIV-2 infections tend to be milder than PIV-1 infections. PIV-4 causes mild upper respiratory tract infection in both adults and children.

PIV-3 is the main strain that causes pneumonia and bronchiolitis. The signs and symptoms are nonspecific, more prominent in children, and similar to, but milder than, those of RSV pneumonia. They include fever, cough, coryza, dyspnea with rales, and wheezing.

Immunosuppression promotes the development of PIV pneumonia. Situations leading to immunosuppression include the following: BMT, solid-organ transplantation (with mild forms), severe combined immunodeficiency in children, or therapy with etanercept.

PIV infection may appear as giant-cell pneumonia. This form is most frequent in immunocompromised patients (after BMT or umbilical-cord transfusion) and rarely associated with alveolar proteinosis. The mortality rate approaches 100% in children, with a better prognosis than this in adults.

PIV pneumonia may mimic other lung infections most commonly encountered in an immunocompromised host. Several clinical findings tend to distinguish PIV or RSV lung infection from CMV or other opportunistic forms of pneumonia: upper respiratory infection before lung infection, clinical and imaging evidence of sinusitis, and wheezing.

As many as one third of children with PIV infection can have bacterial superinfection. Even if long-term sequelae are uncommon, cryptogenic organizing pneumonia is described after PIV infection.

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