Influenza Flashcards
How many main groups of influenza are there?
3
A + B + C
What are the different Influenza surface proteins?
H - 18 different (3 in humans) - viral attachment and entry
N - 11 different - viron to be released
What is antigenic drift vs. shift?
Drift = small change over time
Shift = abrupt major changes - jump from one animal to another
What are influenza clinical features?
Incubation = 2-4 days
Fever which lasts about 3 days
+cough, myalgia, headache and fever
Less common = nausea, vomiting and diarrhoea
What are the swine flu symptoms?
Sudden fever and cough
Tiredness, chills, headache, sore throat, diarrhoea, LOA, muscle and joint pain
How can infection be transmitted?
Airborne
Contact
-Direct
-Indirect
What is virus shedding?
First 4 days of illness
Longer in children and immunocompromised
How long can a virus survive?
24-48hrs on non-porus surface
8-12hrs on porous surfaces
What are common complications of influenza?
Acute bronchitis
Secondary bacterial pneumonia (4-5 days after flu starts)
What are less common complications of influenza?
Primary viral pneumonia
Myocarditis / pericarditis
Transverse myelitis / Guillaine-Barre
Myositis
What is encephalitis lethargica?
Fever, headache, lethargy, sleep reversal
25% mortality
Serology = flu A
What are the diagnosis and investigations of encephalitis lethargica?
Viral nose and throat swabs CXR Blood culture Pulse oximetry Resp rate U+E, FBC, CRP
What is secondary bacterial pneumonia?
Severity = CURB-65
Patients with flu like symptoms and a fever for >4 days = urgent CXR
What is antiviral therapy in influenza?
Use in 48hrs of onset
Neuraminidase inhibitors
Tamiflu + relenza
When is an individual non-infectious in influenza?
24hrs after last flu symptoms
Or when anti-viral therapy is completed
