A recent case study published in the journal Microorganisms highlights a case of severe community-acquired pneumonia (CAP) caused by human metapneumovirus (hMPV) in an older adult male. This case underscores the growing recognition of hMPV as a significant respiratory pathogen, emphasizing the need for accurate diagnostics and targeted interventions.
First identified in 2001, hMPV is increasingly acknowledged as a respiratory virus with substantial health implications. It is associated with a spectrum of respiratory illnesses ranging from mild upper respiratory tract infections to severe lower respiratory tract disease. Symptoms caused by hMPV often overlap with those of other respiratory viruses, complicating diagnosis and treatment. Transmission occurs primarily through sneezing, coughing, close contact, or contact with contaminated surfaces, making healthcare settings particularly vulnerable to outbreaks. The virus remains transmissible for up to a week after symptom onset, posing significant challenges for infection control.
Severe hMPV infections are more common among young children, older adults, and immunocompromised individuals. However, while pediatric cases are well-documented, adult population data remains scarce. CAP remains a leading cause of morbidity and mortality worldwide, with bacterial CAP incidence declining due to vaccination programs. Despite this progress, significant knowledge gaps persist regarding viral etiologies of severe CAP requiring hospitalization.
Costa-Filho and colleagues in their study in Brazil described the case of a 68-year-old immunocompetent male with severe pneumonia caused by hMPV. The patient had a history of mild systemic arterial hypertension, dyslipidemia, and chronic aspirin use. It was noted that he was physically active, a non-smoker, and without obesity, diabetes, or other comorbidities. The case highlights that even individuals with minimal risk factors can develop severe disease.
The patient initially presented with intermittent dry cough and mild odynophagia on day one (D1). By day two, symptoms had progressed to nasal congestion, rhinorrhea, nocturnal sweating, and allodynia. A self-administered nasopharyngeal swab test for SARS-CoV-2 was negative. Despite receiving amoxicillin-clavulanate, prednisone, and clarithromycin, his condition worsened, with symptoms such as intense coughing, bronchospasm, myalgia, fatigue, and headache prompting emergency department admission on day seven (D7).
Laboratory tests revealed elevated inflammatory markers, including C-reactive protein (7.6 mg/dL) and D-dimer (870 ng/mL), mild thrombocytopenia, and normal procalcitonin and leukocyte levels, suggesting a viral etiology. Thoracic computed tomography (CT) scans showed significant pulmonary involvement, including mild bilateral pleural effusions, ground-glass opacities, and areas of consolidation, consistent with viral pneumonia. Molecular testing using a multiplex reverse-transcription polymerase chain reaction (RT-PCR) panel identified hMPV as the sole pathogen.
The patient received nebulization with oxygen, intravenous moxifloxacin, salbutamol, ipratropium bromide, and physiotherapy during hospitalization. Stabilization occurred within 24 hours, and he was discharged on oral moxifloxacin. Full recovery was achieved by day 14 post-discharge. Hematological markers showed minimal fluctuations, and platelet levels normalized within the day of admission.
This case underscores the potential for hMPV to cause severe pneumonia even in immunocompetent adults with no significant comorbidities. Radiological findings, such as ground-glass opacities and bilateral consolidations, are characteristic of viral pneumonia, supporting the diagnosis. Despite molecular testing identifying hMPV as the sole pathogen, antibiotic therapy was initiated, reflecting diagnostic uncertainties in distinguishing bacterial from viral infections. Emphasizing the need for rapid diagnostics to optimize management is important. The global underdiagnosis of hMPV calls for increased clinician awareness, integration of hMPV testing into routine diagnostics, and investment in therapeutic strategies, including promising vaccines like the bivalent IVX-A12 targeting hMPV and RSV, to improve preventive measures and clinical outcomes.
Reference
- Costa-Filho RC, Saddy F, Costa JLF, Tavares LR, Castro Faria Neto HC. The Silent Threat of Human Metapneumovirus: Clinical Challenges and Diagnostic Insights from a Severe Pneumonia Case. Microorganisms. 2025 Jan;13(1):73.