Influenza Flashcards
What makes up Influenza virus?
Different segments of RNA
How many main types of influenza are there?
3 (A,B,C)
What does influenza A act on?
Humans and animals, causes pandemics
What does influenza B act on?
Human, doesn’t cause pandemics
What does influenza C do?
Mild disease
What are the 2 surface proteins that are targets for neutralization?
Hemaglutinin
Neuraminidase
How many hemaglutinins are there?
15
How many neuraminindases are there?
10
Why does Influenza have a high mutation rate?
They are RNA viruses
What changes in Influenza from year to year?
Sequence of H1 and N1 proteins
Changing surface proteins from year to year is called what?
Antigenic drift
How many genes are encoded on one strand of RNA
1
How do viruses gain new genes?
During virus envelope formation gene segments from other viruses can incorporate themselves.
What is it called when new hemagglutinin or neuraminidase genes are obtained?
Antigenic shift
Animal responsible for origin and spread of influenza to other animals?
Duck
Where did spanish flu come from?
Bird to human
Next anticipated pandemic?
Novel H1N1
How long will a strain of influenza circulate?
Unpredicatable
How is influenza transmitted?
Large droplets like sneezes and coughs
Limiting factor of transmission?
Large droplets don’t stay in air so close contact needed
Does it remain on surfaces?
Not important for transmission
Can you get influenza from pork or chicken meat?
No
How does influenza present?
Fever, headache, myalgia, and fatigue
What are not typical features of influenza?
Nausea, vomiting, and diarrhea
What causes Reye’s syndrome?
Giving aspirin to kids
Most common causes for secondary bacterial infection pneumonia?
Step pneumonia and staph aureus
Most common cause of death in Spanish Flu?
Bacterial pneumonia
What happened with vaccines made from killed bacteria used on Spanish Flu?
it helped (improved mortality rates)
Who does the “Bird Flu”/H5N1 affect?
Children and young adults
Presentation of H5N1?
Respiratory illness, but also diarrhea and neurologic problems
Who was affected by Avian Influenza H7N9 in 2013?
Elderly
How do you diagnose Influenza?
Rapid antigen tests
Gold standard for diagnosis?
Viral culture, but takes days
What is the best diagnostic test?
RT-PCR, expensive
Which antiviral is used for treatment?
None of them work great
Why aren’t Amantadine or Rimantadine used anymore?
All strains are resistant to it
New treatments?
Neuraminidase inhibitors Oseltamivir and Zanamivir
When do these neuraminidase inhibitors need to be given by?
within 48 hours of symptom onset, reduces symptoms by 1-2 days
How is Zanamivir given?
Oral inhalation, but IV available
How is it determined which strains will be predominant in upcoming flu year?
Educated guesses
How long does it take to make vaccines?
9 months
Where are vaccines grown?
Eggs
What is done with egg containing virus?
Purified and virus inactivated with formaldehyde
What constitutes a “split” vaccine?
Vaccine that separates Hemagglutinin and neuraminidase surface proteins in vaccine for less side effects
What is a trivalent vaccine?
Vaccine with two A strains and 1 B strain
Quadrivalent strain?
Vaccine with two A strains and 2 B strains
What complication was noticed with vaccines in 1976?
Guillain-Barre
What do you give for people allergic to eggs?
Cell culture based vaccine
Does live attenuated vaccine give better protection?
Not proven
Who are vaccines most effective for?
Least effective?
Children
>65 elders
