influenza Flashcards
what are the different types on influenza virus ?
A - mammals and birds
B, C - only humans
RNA virus, 8 genome
what are the different surface proteins for influenza ?
Haemagglutinin (H) 18 types - facilitates vial attachment and entry to host cell
Neuraminidase (N) 11 types - enables new vision to be released form host cell
what is the process that causes major change and forms new subtypes of flu ?
antigenic shift
what are the requirements for a pandemic ?
human pathogenicity
new virus - antigenic shift
efficient person-person transmission
what are the clinical features of influenza ?
incubation 2-4 days abrupt fever up to 41 plus 2 or more of: cough, throat symptoms, myalgia, headache, malaise predominant systemic symptoms less common - N+V, diarrhoea
how is influenza spread ?
airborne - large droplets
contact
virus survives 24-48 hours on non-porous surface
8-12 hours on porous surface
who is at risk of complicated influenza ?
chronic diseases DM severe immunosuppression age >65 pregnancy children under 6 months morbid obesity
what are common respiratory complications of influenza ?
acute bronchitis
secondary bacterial pneumonia
what are less common complications of influenza ?
primary viral pneumonia - avian flu
cardiac - myocarditis/pericarditis
CNS - GBS, myositis
how do you investigate influenza ?
viral nose and throat swab - PCR chest X-ray blood culture oximetry - <92 need ABG + O2 FBC, U+Es, CRP
how do you treat influenza ?
antivirals
tamiflu (oseltamivir)
zanamivir
what are side effects of tamiflu ?
nausea, vomiting, abdo pain, diarrhoea
less common - headache, hallucinations, insomnia, rash
renal dose needed
when is someone non-infectious ?
24 hours after last symptoms
when anti-viral therapy is complete
what is in the seasonal flu vaccine ?
2 type A and 1 type B virus
grown in chick egg embryos, so contraindicated in egg allergy
