Influenza Flashcards
When does season influenza occur in the northern hemisphere?
Dec-Feb
What type of virus is influenza?
RNA virus
What are the 3 main groups of influenza?
Influenza A
Influenza B
Influenza C
What types of influenza can infect humans?
B and C
What is antigenic drift?
Mechanism of genetic variation in the virus - occurs continually over time, small on-going point mutations
What is antigenic shift?
Abrupt major change in the virus which enables a flu strain to jump from one species to another
What is the difference between seasonal and pandemic flu?
Pandemic occurs sporadically and has more serious complications
What are requirements for pandemic flu?
Human pathogenicity
Virus undergone antigenic shift
Efficient person-person transmission
What are clinical features of influenza?
Incubation period of usually 2-4 days Abrupt fever up to 41 lasting 3 days 2 of - cough, sore throat, rhinorrhoea, myalgia, headache, malaise Predominance of systemic symptoms Rarely - nausea, vomiting, diarrhoea
How is influenza like illness defined?
Fever>38 AND cough+onset within the last 10 days
What are symptoms of swine flu excluding fever and cough?
Tiredness/chills Headache Sore throat Runny nose Sneezing Diarrhoea/stomach upset loss of appetite Aching muscles, limb, joint pain
How is influenza transmitted?
Airborne - person
Person - person via droplets
Contact
How long can influenza survive?
24-48 hours on non-porous surfaces
Who is at high risk of highly complicated influenza?
Neuro/hepatic/renal/pumonary/chronic cardiac disease Diabetes mellitus Severe immunosuppression Age over 65 years Pregnancy Children under 6 months Morbid obesity (BMI>40)
What are common resp complications of influenza?
Acute bronchitis
Secondary bacterial pneumonia
