Clinical Features and Outcomes Associated With Parainfluenza Virus-Associated Pneumonia

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Researchers found limited clinical variability between PIV serotypes and substantial overlap in presenting signs and symptoms for PIV and other etiologies.

There are few differences among pneumonia cases by parainfluenza virus (PIV) serotype and no identified clinical characteristics that can reliably distinguish PIV from other pathogen types at presentation, according to study results published in Clinical Infectious Diseases.

Study results also indicated that, in both children and adults, the severity of PIV-associated pneumonia was similar to severity of pneumonia cases associated with other viruses.

In this prospective, population-based active surveillance study, researchers enrolled children and adults with radiographically confirmed community-acquired pneumonia from January 2010 through June 2012 at 8 hospitals in 4 US cities (Memphis, Tennessee; Nashville, Tennessee; Chicago; and Salt Lake City) to determine the clinical features and outcomes associated with PIV-associated pneumonia (PIV-1, PIV-2, and PIV-3) and to compare these among PIV serotypes 1, 2, and 3 as well as pneumonia caused by other viruses as well as atypical and typical bacterial pathogens. Samples of patients were compared with a control group comprised of asymptomatic children and adults without respiratory symptoms in the prior 14 days.

Of the 4651 patients, PIV was detected in 221 patients by nasopharyngeal/oropharyngeal polymerase chain reaction and/or serologic testing (155/2354 children [6.6%] vs 66/2297 adults [2.9%]; P <.001). PIV was the sole pathogen detected in 50% of the cases. Other viruses commonly co-detected with PIV included human rhinovirus (13%), respiratory syncytial virus (12%), and adenovirus (11%). Bacterial pathogens were co-detected with PIV in 16% of patients. Compared with children and adults in the control group, PIV was detected significantly more in children and adults with pneumonia (P <.001 and P =.005, respectively).

Children with PIV-3-associated pneumonia were significantly younger than children with PIV-1-associated and PIV-2-associated pneumonia; 62% of PIV-3 detections occurred in children <2 years, compared with 29% to 32% of PIV-1 and PIV-2 detections. Cough was significantly more common in children with PIV-1 and PIV-3 than in PIV-2 detections (P =.03), and rhinorrhea occurred most commonly in PIV-3 detections (P =.04). In adults, PIV-1, PIV-2, and PIV-3 infections were similarly distributed by age, and there were no differences in clinical characteristics.

In multivariable analysis, children with bacterial pneumonia exhibited increased odds of more severe disease than children with PIV-associated pneumonia exhibited (odds ratio [OR], 8.42; 95% CI, 1.88-37.80). Odds of more severe disease did not significantly differ between PIV and other viruses, atypical bacterial pathogens, or pneumonia with no pathogen detected. Compared with PIV-associated pneumonia, bacterial pneumonia (adjusted hazard ratio [aHR], 0.36; 95% CI, 0.24-0.54) and pneumonia with no pathogen detected (aHR, 0.78; 95% CI, 0.67-0.91) were associated with lower rate of discharge. In adults, PIV-associated pneumonia exhibited similar severity to other pneumonia pathogens. Length of hospital stay, however, differed significantly among groups, with other viral (aHR, 0.77; 95% CI, 0.63-0.95), bacterial (aHR, 0.39; 95% CI, 0.26-0.58), and pneumonia with no pathogen detected (aHR, 0.72; 95% CI, 0.57-0.90) associated with longer length of hospital stay compared with PIV.

Researchers noted that the findings of this study may not represent the full spectrum of clinical manifestations of overall PIV infection, since community-acquired pneumonia is not the most commonly associated respiratory syndrome with PIV infection.

Other study limitations include discordance between polymerase chain reaction and serologic test results, attributable to several factors including test sensitivity, and a reduction in the yield of bacterial cultures due to antibiotic use prior to hospitalization, which may have underestimated the prevalence of bacterial pneumonia.

“While PIV is recognized as an important etiology of respiratory illnesses in children, our findings underscore the importance of PIV as an etiology of pneumonia requiring hospitalization in both children and adults,” the researchers concluded.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Howard LM, Edwards KM, Zhu Y, et al. Parainfluenza virus types 1-3 infections among children and adults hospitalized with community-acquired pneumonia [published online July 18, 2020]. Clin Infect Dis. doi:10.1093/cid/ciaa973