Influenzae Flashcards
There are 3 main types of influenza
A, B, C
Influenza A infects
humans and animals; pandemics
Influenza B infects
infects human; no pandemics
Influenza C results in
mild disease
2 surface proteins of Influenza
Hemaglutinin and neuraminidase
Serological types of hemaglutinin
H1-H15
Serological types of neuraminidase
N1-N10
Influenza nucleic acid
RNA
Results of having RNA as nucleic acid
-higher mutation rate
Definition of antigenic drift
Slow change of the presentation of H and N proteins of the surface
Definition of antigenic shift
Sudden incorporation of new piece of RNA from different influenza viruses.
One animal that is the true carrier of influenza
Ducks
Transmission of influenza can occur among which species
ducks to humans, pigs, poultry, horses, whales/seals
H1N1 colloquially known as
1918 spanish influenza
1957 asian influenza a combination of
H2N2 avian virus + H1N1 human virus = H2N2
1968 hong kong influenza
H3 avian virus + H2N2 human virus = H3N2
Timeline of influenza
H1N1 => H2N2 => H3N2 and H1N1
-normally one major strain circulating at one time
Transmission of influenza
- need large droplets from sneezing and coughing
- close contact
- contaminated surfaces not important for transmission
- no transmission through meat
Clinical illness
- fever most common with headache, myalgia, fatigue
- URI symptoms follow; cough, sore throat, nasal drip
- fatigue and weakness may last for pure
Symptoms that are misconstrued as classic influenza symptoms
nausea, vomiting, diarrhea
Complications of influenza
- viral pneumonia
- bacterial pneumonia; Strep pneumoniae, S.aureus
- myositis and rhabdomylosis
- MI
- encephalitis, encephalopathy
- Reye’s syndrome(hepatic encephalopathy, necrosis)
Unique to spanish flu
- infection started with typical symptoms, worsened
- bacterial pneumonia most common cause of death
- aspirin given high doses
Unique to bird flu
- primarily children and young adults
- high mortality rates, 60%
- diarrhea and neurologic components
Avian influenza H7N9
- primarily occurred in china 2013
- elderly more affected
- severe respiratory illness
- no evidence about human transmission
Mortality of influenza
- 3000 deaths
- severe years or pandemics: 45k deaths
Diagnosis of influenza
- rapid antigen test with moderate sensitivity
- viral culture
- serology not helpful
- PCR highly sensitive
Treatment of influenza
- no antivirals work great
- Amantidine and Rimantadine; all current strains resistant
- Nueraminidase inhibitors; Oseltamivir and Zanamivir
- best reduce symptoms by 1-2 days if taken within 48hrs
Zanamivir
- oral inhalation
- iv form possible
Concept of influenza vaccine
- new vaccines every year due to antigenic drift
- educated guesses
- 9months to develop vaccine
Production of vaccine
- grown in eggs
- 1 egg for every shot
- vaccine are purified and virus is inactivated with formaldehyde
Current components of vaccines
- 2 A strains and 1 B strain, an H3N2 strain and an H1N1 strain
- 2 A and 2 B strains
- current contains H1N1 2009
Side effects of vaccine
- not possible to get flu from vaccine
- Guillain barre syndrome
Vaccine effectiveness
- vaccines most effective in children
- in those >65, vaccines not very effective
