[Clinical features of pneumonia associated with influenza virus infection]
1First Department of Internal Medicine, Kagawa Medical University.
Abstract:
The history of influenza pandemics was reviewed and clinical manifestations of pneumonia associated with influenza virus infections are described. Several types of pneumonia associated with the influenza virus infection have been reported: 1) influenza complicated by secondary bacterial pneumonia, 2) primary influenza virus pneumonia, 3) combined influenza virus and bacterial pneumonia. Secondary bacterial pneumonia often produces a syndrome that is clinically distinguishable from that of primary viral pneumonia. In primary influenza virus pneumonia, chest roentgenography revealed bilateral infiltrations but no consolidation. Histologically, diffuse alveolar damage and hemorrhagic bronchiolitis were frequently observed in primary influenza virus pneumonia, in which case the prognosis was the worst. Although rare, the possibility of bronchiolitis obliterans organizing pneumonia associated with influenza virus infection should be recognized. H. influenzae, S. pneumoniae, or S. aureus were frequently associated with influenza viral infection, and treatment against these bacteria should be considered.
Insights
Influenza virus infections can cause various types of pneumonia, including secondary bacterial pneumonia and primary viral pneumonia. Primary influenza pneumonia has the worst prognosis, often showing diffuse alveolar damage.
Area of Science:
- Infectious Diseases
- Pulmonology
- Virology
Background:
- Influenza pandemics have a significant history, with pneumonia being a major complication.
- Understanding the clinical and histological manifestations of influenza-associated pneumonia is crucial for patient outcomes.
Observation:
- Influenza virus infections can lead to three main types of pneumonia: secondary bacterial, primary viral, and combined.
- Primary influenza virus pneumonia is characterized by bilateral infiltrations on chest X-rays without consolidation.
- Histological findings in primary influenza pneumonia include diffuse alveolar damage and hemorrhagic bronchiolitis.
Findings:
- Primary influenza virus pneumonia presents distinct clinical and radiological features compared to secondary bacterial pneumonia.
- The prognosis for primary influenza virus pneumonia is the most severe.
- Bronchiolitis obliterans organizing pneumonia is a rare but recognized complication of influenza virus infection.
Implications:
- Early recognition of primary influenza pneumonia is vital due to its poor prognosis.
- Co-infections with bacteria like *Haemophilus influenzae*, *Streptococcus pneumoniae*, or *Staphylococcus aureus* are common.
- Empirical antibiotic treatment should be considered in patients with influenza-associated pneumonia due to frequent bacterial co-infections.
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