Severe acute respiratory distress syndrome associated with human metapneumovirus infection in a morbidly obese adult.

Human metapneumovirus (hMPV) is a recognized cause of respiratory tract infections and can occasionally lead to severe pneumonia and acute respiratory distress syndrome (ARDS) in adults. However, reports describing the clinical course and management of hMPV-associated ARDS in adults remain limited. We report a case of severe ARDS caused by hMPV infection in a morbidly obese adult who achieved a favorable outcome with standard ARDS management. A 58-year-old man with morbid obesity (body mass index 36.6 kg/m²) was admitted to a previous hospital with fever and cough. Due to rapidly progressive hypoxemia, he was transferred to our hospital. On arrival, he exhibited severe hypoxemia (PaO₂/FiO₂ ratio of 90 mmHg) and was diagnosed with severe ARDS based on the global definition of ARDS, requiring invasive mechanical ventilation. Respiratory multiplex polymerase chain reaction testing identified hMPV on hospital day (HD) 2, and systemic corticosteroid therapy was discontinued because bacterial infection was considered unlikely. Standard ARDS management, including a low tidal volume strategy and prone positioning under neuromuscular blockade, resulted in rapid improvement in oxygenation. The patient was extubated on HD 5 and subsequently managed with high-flow nasal cannula oxygen therapy and noninvasive positive pressure ventilation. He was discharged on HD 11 without supplemental oxygen. This case highlights that hMPV infection can cause severe ARDS in morbidly obese adults and underscores the importance of early etiological diagnosis using respiratory multiplex PCR testing, as well as appropriate implementation of standard ARDS management, even in severe ARDS.