influenza Flashcards
What is influenza virus
An RNA virus which is part of the orthomyoxoviridae
What does influenza A infect
mammals and birds
What does influenza B and C infect
Only humans
What are the 2 main antigens on influenza
hAEMAGGLUTIN AND NEURAMINIDASE
What does haemagglutin do
Facillitates the viral entry into the host cell and attachment
What is the function of neuraminidase
Aids in the virus proteins being released from the host cells
What is antigenic drift
Gradual changes to the virus over time via mutations which can change the antigenic properties in a way that the immune system will not recognise the antigen
What is antigenic shift
Abrupt major change resulting in new haemagglutin and neuraminidase combinations
This is what allows strands to jump between species
What is required for a pandemic to be classified
It has to be able to infect humans
It has to be a new virus and undergone antigenic shift or drift so that the population is succeptible
It should be transmissible between humans
What is the incubation period for influenza
2-4 days
What are the symptoms of influenza
Sudden fever over 38 which lasts 3 days
cough, sore throat, rhinorrhoea (runny nose), myalgia, headache and malaise
Nausea, vomiting and diarrhoea are less common symptoms
What stage is influenza most infective
vIRAL SHEDDING - FIRST 4 DAYS
what are common resp complications of influenza
Acute bronchitis
Secondary bacterial pneumonia - appears 4-5 days after influenza
What bacteria commonly causes the pneumonia which appears after flu
staph aureus
What are the investigations and diagnosis for Influenza
Viral nose and throat swab - then PCR
Chest X-ray
blood culture
resp rate
U&Es, FBC nad CRP
When should antiviral therapy be started influenza
Within 48 hours of symptoms onset
Which antivirals are used in influenza
Oseltamivir - oral - side effects nausea, vomiting, abdo pain and diarrhoea - first line
Zanamivir - inhaled or IV - side effects bronchospasm - 2nd line
Can oseltamivir be used in pregnancy
Yes, it is not a teratogen
What antigen do the antivirals target
Neuraminadase
What do the vaccines target
The haemagglutinin
