Influenza Flashcards
What is influenza?
Acute febrile respiratory viral infection
Influenza is characterized by sudden onset of symptoms and is primarily caused by influenza viruses.
When do influenza outbreaks usually occur?
Annual outbreaks, primarily in late autumn and winter
Endemics typically occur during these seasons.
Which types of influenza are responsible for most deaths?
Influenza A, less commonly influenza B
Influenza-related deaths are predominantly due to influenza A.
What factors contribute to zoonotic influenza outbreaks?
Close proximity of humans to swine or poultry
These outbreaks are more prevalent in specific regions.
What is the pathophysiology of influenza?
Attaches to epithelium of bronchi and trachea, leading to replication and destruction of epithelial cells
Epithelial cells take 3-4 weeks to regenerate.
List the four types of influenza viruses.
- Influenza A
- Influenza B
- Influenza C
- Influenza D
Which types of influenza cause seasonal epidemics?
Influenza A and B
These viruses are responsible for the typical annual outbreaks.
What type of influenza is associated with pandemics?
Influenza A
Influenza A is known for causing widespread pandemics.
What are common symptoms of influenza?
- Sudden onset of fever
- Chills
- Rigours
- Headache
- Myalgia
- Lethargy
- Dry cough
- Sore throat
- Nasal discharge
- Hoarse voice
- Nausea
- Vomiting
- Diarrhoea
- Cervical lymphadenopathy with tenderness
What are signs of complicated influenza presentation?
- Significant exacerbation of underlying conditions
- CNS involvement
- Lower respiratory tract infections (LRTIs)
- Myositis
How is influenza typically diagnosed?
Clinical diagnosis during peak incidence seasons; gold standard is lab tests
Lab tests include rapid molecular assays and RT-PCR.
What are some laboratory tests used for influenza diagnosis?
- Rapid molecular assays
- Reverse Transcription PCR (RT-PCR)
- Nucleic Acid Amplification Tests
- Rapid influenza diagnostic tests (RIDTs)
- Immunofluorescence
- Viral cultures
What is the management approach for uncomplicated influenza?
Usually resolves spontaneously; antivirals can be prescribed for at-risk individuals
Antivirals are particularly important for immunocompromised patients.
What are the first-line antivirals for influenza?
- Neuraminidase inhibitors
- Oseltamivir
- Zanamivir
- Peramivir
When should antivirals ideally be started for influenza?
Within 2 days of influenza onset
Early treatment is crucial for effectiveness.
