Influenza Flashcards
Major community acquired resp viruses
1) orthomyxovirus = influenza A, B, C
2) paramyxovirus = parainfluenza virus 1-4, RSV A, B
3) picronavirus = coxsackie
4) herpes virus
5) adenovirus
6) corona virus
7) papilloma virus
epidemiology pattern of outbreaks
1) distinct outbreaks every year
2) outbreaks begin abruptly for 2-3 weeks and last 2-3 months
why does influenza cause disitnct outbreaks every year
1) periodic changes in envelope glycoproteins (hemagglutinin, neuraminidase)
distinguish antigenic shifts v. antigenic drifts
antigenic shifts = major change in glycoproteins
= epidemics and pandemics
antigenic drifts = minor change in glycoproteins
= localized outbreaks
distinguish between IFN A vs. IFN B
1) IFN A = H1, H2, H3 and N1, N2
2) IFN B = less propensity for antigenic changes only drifts in hemagglutanin
Pathogenesis of influenza
1) Initiation = IFN hemagglutanin binds sialic acid on respiratory epith cell surface glycoproteins
2) after viral replication, progeny virions also bound to host cell membrane
3) neuramindase cleaves links to liberate new virions and spreads infection
Symptoms of respiratory virus
1) fever,
2) runny nose, sore throat
3) coughing, wheezing
4) n/v/d
which patient population is most affected by mortality with influenza
elderly and infants
complications of influenza infection (4)
1) primary IFN pneumonia
2) secondary bacterial pneumonia
3) myositis/rhabdomyolysis
4) CNS involvement
Diagnosis of influenza
1) Rapid antigen test
2) immunofluorescence
3) PCR
4) 48 hr viral culture
5) serologic testing
Prevention of influenza
Flu vaccine targets who?
1) 6 months - 18 yrs
> 50 yrs
2) nursing homes/chronic care
3) chronic diseases
4) pregnancy
5) healthcare
Treatment of influenza
2 classes of antivirals
1) neuramindase inhibitors = active against IFN A and B
(oseltamavir and zanamivir)
2) adamantanes (amantidine and rimantidine)
when to give antivirals
within 24-30 hrs
