A 48-Year-Old Previously Healthy Man Presenting with Acute Respiratory Distress Syndrome (ARDS), Negative Tests for SARS-CoV-2, and Positive Serology for Parainfluenza Virus Type 3 (PIV-3).

BACKGROUND Human parainfluenza viruses (PIVs) belong to the Paramyxoviridae family. PIVs cause lower respiratory tract infections in children and the elderly. In addition, severe pneumonia due to PIVs has been reported in immunocompromised adults. However, no reports have described PIV infections leading to acute respiratory distress syndrome (ARDS) in immunocompetent hosts. CASE REPORT A 48-year-old otherwise healthy man was transported to our hospital due to worsening dyspnea. On arrival, strong effortful breathing was observed and results of arterial blood gas analysis revealed severe hypoxia. On the basis of the clinical presentation, we intubated the patient for mechanical ventilation. However, mechanical ventilation provided inadequate oxygenation. Finally, veno-venous extracorporeal membrane oxygenation was initiated. Pneumonia was considered to be a cause of the ARDS, based on the patient's history and blood examination. Repeated reverse transcription-polymerase chain reaction tests for the novel coronavirus were performed, and endotracheal aspirate specimens were cultured for bacteria and fungus; however, the results were all negative. On day 2, the PIV-3-specific antibody titer was elevated. Two weeks later, the PIV-3-specific antibody titer had increased 4-fold. On the basis of these results, we diagnosed pneumonia induced by PIV-3 infection. CONCLUSIONS ARDS can occur because of severe pneumonia induced by PIV-3. In cases of unexplained severe pneumonia or ARDS, PIV infection should be included in the differential diagnosis.