Fact-sheet: Flu - influenza pneumonia
Updated on 09/17/2021 at 12:16 PM
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Definition
Acute viral disease, highly contagious, occurring in epidemic form.
The causative agent is Myxovirus influenzae, an RNA virus of the Orthomyxoviridae family.
Three major, clearly distinct types are recognized (A, B, C).
The main characteristic of this virus is its marked genetic lability.
Transmission is direct human-to-human, via the airborne route.
Clinical features
A distinction is made between common influenza in the healthy adult, with an incubation period of 24-72 hours; after the invasion phase (high fever, malaise), the established phase is characterized by intense general symptoms (fever, tachycardia, asthenia...) and a relative paucity of physical findings.
Complicated influenza, occurring mainly in debilitated patients, most often corresponds to bacterial superinfection by H. influenzae.
Malignant influenza, a direct manifestation of the virus, presents as lesional pulmonary edema.
CT
Findings may present, in order of frequency:
- Focal ground-glass opacity, most often peripheral or diffuse.
- Areas of alveolar consolidation, segmental or non-segmental
- Pleural effusion
- Bronchiolitis
- Occasionally normal imaging
Management
Treatment remains primarily symptomatic