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
What are uncommon resp complications of influenza?
Primary viral pneumonia
Rapid resp failure
What are uncommon cardiac complications?
Myocarditis/pericarditis
What are uncommon complications of CNS?
Transverse myelitis
Guillan-Barre
Myositis and myoglobinuria
What investigations are done for influenza?
Viral nose and throat swabs CXR Blood culture Pulse oximetry Resp rate U&Es FBC CRP
When is a patient at high risk of secondary bacterial pneumonia?
Flu symptoms and fever for >4 days
How is pneumonia severity assessed?
CURB65
What is CURB65?
Confusion Urea >7mmol/l Resp rate >30 Blood pressure .65 years of age
What antivirals should be given for influenza?
Oseltamivir
Zanamavir
Should antivirals be given in therapy?
Yes
