Influenza Flashcards
what was a consequence of getting swine flu shots in the 1970’s?
Guillan Barre
-hundreds of cases
why is it so easy for influenza to mutate?
segmented RNA genome
- can swap out genes really simply
- can have genes from different virus
main type of influenza
type A (epidemics) Type B (non-epidemic)
what are the neutralizing targets for influenza?
hemagglutinin
neuraminidase
since influenza is RNA viruses, what does that mean?
high mutation rate
antigenic drift
- change their sequences of H1 and N1 proteins from year to year in process of antigen drift
- ensures host wont have neutralizing antibodies to future stains
antigenic shift
causes pandemic
- each gene of influenza is encoded on a separate strand of RNA
- when virus enveloped is formed, gene segments from different viruses that have infected the same cell can be incorporated into virus
- acquires new hemagglutinin or neuraminidase genes
transmission of influenza
need large droplets
- sneezing, coughing
- large droplets dont stay suspended in hair-> close contact
clinical illness of influenza
fever headache myalgia fatigure cough sore throat nasal discharge fatigue weakness
not typical symptoms of influenza
N&V, diarrhea
Complications for Influenza
Viral pneumonia
Bacterial pneumonia-> strep p. and staph aureus
Myositis and rhabdomyolysis
Myocardial infarction
Encephalitis, encephalopathy
Reyes syndrome-> aspirin not used anymore really except to prevent heart attacks
Unique things to Spanish flu
infected started out fine but then got worse
-bacterial pneumonia most common cause of death
Unique to “Bird” flu
- affects primarily in children and young adults
- very high mortality
- respiratory illness
- diarrhea and neurological components
- little person to person transmission
Avain influenza H7N9
-china
elderly
severe respiratory illness
H3N2 variant influenza
Indiana state fairs
- close contacts with pigs
- mild disease
- no sustained transmission
- 2009 H1N1 and pig H3N2 strain
Diagnosis of influenza
- rapid flu tests-> ELISA, look for antigen for strain
- only 60% sensitive
Best test for diagnosis
RT-PCR, very sensitive (90%)
Expensive
Gold standard of diagnosis
Viral culture-> takes too long though
Treatment
- antiviral doesn’t work
- resistant to amantadine and rimantadine
New drugs that influenza not resistant too
-inhibit neuraminidase-> stop spread throughout the body
oseltamivir
zanamivir
when does medication need to be taken by?
Within 48 hours of symptoms onset
-at best reduces symptoms by 1-2 days
Zanamivir
- oral inhalation
- IV form
how does antigenic drift effect vaccines?
-have to make new vaccines every year
How do they guess what new vaccines to make?
-educated guess
Trivalent vaccine, but three in there: usually 2 A strains and 1 B strain
