The Silent Threat of Human Metapneumovirus: Clinical Challenges and Diagnostic Insights from a Severe Pneumonia Case

Abstract

Background: Human metapneumovirus (hMPV) is a respiratory pathogen that has gained increasing recognition due to advancements in molecular diagnostic tools, which have improved its detection and characterization. While severe disease manifestations are traditionally associated with pediatric, elderly, or immunocompromised patients, hMPV-related pneumonia in immunocompetent adults remains underexplored.

Methods: This case report describes a 68-year-old male who developed severe community-acquired pneumonia (CAP) caused by hMPV despite being immunocompetent and having no significant comorbidities. The diagnosis was confirmed via multiplex RT-PCR, excluding bacterial and viral coinfections. Laboratory and imaging findings supported a viral etiology, while empirical antibiotics were initially prescribed due to diagnostic uncertainty.

Results: The patient presented with respiratory symptoms that progressed to hypoxia, productive cough, and fatigue, requiring hospitalization. Imaging revealed bilateral ground-glass opacities and consolidations typical of viral pneumonia. Molecular diagnostics enabled accurate pathogen identification and guiding appropriate management, and the patient fully recovered with supportive care.

Conclusion: This case underscores the importance of rapid molecular diagnostics for hMPV, reducing unnecessary antibiotics and enhancing management. Routine incorporation of hMPV testing into clinical protocols could improve the diagnosis and resource use. The development of vaccines, such as the IVX-A12 in phase II trials, offers hope for targeted prevention, underscoring the need for further research and therapeutic innovations.

Keywords: community-acquired pneumonia (CAP); emerging respiratory viruses; human metapneumovirus (hMPV); immunocompetent adults; rapid molecular diagnostics.

Figure 1

Timeline of symptom progression and clinical events leading to hospital admission. The diagram illustrates the patient’s clinical course from symptom onset (Day 0) to hospital admission (Day 7). The patient’s recent domestic trip to a resort in Angra dos Reis, located two hours by car from Rio de Janeiro, was uneventful and posed no risk of tropical or endemic infections. Key events highlight the progression from mild respiratory symptoms to severe disease, marked by hypoxia and fatigue, necessitating hospitalization. Therapeutic interventions and diagnostic milestones are also described.

Figure 2

Axial computed tomography (CT) image of the thorax. The image shows bilateral ground-glass opacities with a reticular pattern interspersed with focal areas of consolidation and peripheral bronchiolar filling. The red arrows highlight specific areas of consolidation surrounded by ground-glass opacities, which are more prominent in the peripheral and lower lung regions. These findings suggest a diffuse inflammatory or infectious process involving the pulmonary interstitial and peripheral airways (acinus and bronchioles), which is consistent with viral pneumonia.

Figure 3

Computed tomography (CT) image of the paranasal sinuses in the sagittal plane. The image shows mucosal thickening and partial opacification in the frontal sinus (highlighted by the superior red arrow) and ethmoid air cells (highlighted by the inferior red arrow). Narrowing of the sinus drainage pathways is also evident. These findings are consistent with those of acute and subacute sinusitis.