Influenza

Question 1

T or F: Influenza causes an acute febrile respiratory disease

Answer 1

TRUE, doesn’t cause the so called “stomach flu”

Question 2

What is the genome of influenza?

Answer 2

made of 8 different pieces of (-)ssRNA which encode several different viral proteins

Question 3

What surrounds the genome of influenza?

Answer 3

core is covered by lipid envelope, with a lining of matrix protein on the inner side of the envelope.

Question 4

What are the 2 most characterized proteins of influenza?

Answer 4

hemagglutinin (H) and neuraminidase (N) glycoproteins. Different types of these are numbered (that how you get H1N1 or H3N2) and are on viral coat

Question 5

How many types of influenza virus are there?

Answer 5

3. Type A, B, and C. Type C cause milk or insignificant illness

Question 6

What is significant about Type A strains?

Answer 6

cause both epidemics and pandemics. Can also infect other animals (horses, seals, swine, and birds)

Question 7

How does influenza nomenclature work?

Answer 7

Virus type/Geographic origin/Stain number/ Year of isolation (Virus subtype). Example A/Moscow/21/99 (H3N2)

Question 8

What is antigenic drift?

Answer 8

gradual changes in the virus that occurs through a slow series of mutations, substitutions, or deletions in amino acids constituting the H and N surface antigens

Question 9

What causes antigenic drift?

Answer 9

point mutations in response to antibodies after virus strain is established in humans.

Question 10

What is antigenic shift?

Answer 10

occurs when a type A influenza with a novel hemagglutinin or neuraminidase gene segment is introduced into humans

Question 11

How does antigenic shift occur?

Answer 11

Gene reassortment can occur when 2 or more influenza viruses infect a single human or animal

Question 12

Why does antigenic shift occur?

Answer 12

segmented genome means gene segments can be swapped between strains

Question 13

What makes pigs so special?

Answer 13

That can be infected by strains from 3 different species: birds, pigs, and humans. This makes pigs great “mixing vessels” for presenting novel influenza to a new species.

Question 14

Where is 2009 H1N1 come from?

Answer 14

multiple reassortments of avian, human, and swine flu in pigs.

Question 15

T or F: Type A and B can go through antigenic shift

Answer 15

FALSE, only Type A can because B only infects humans

Question 16

How is Influenza transmitted?

Answer 16

Respiratory route. Droplet and small particle aerosols. Also can live on fomites for hours to days. Lives on hands for 5 min

Question 17

How does influenza infection present?

Answer 17

acute onset of fever, chills, myalgias, headache, and cough

Question 18

T or F: neonates and infacts are infected much worse with influenza

Answer 18

TRUE, can present with decreased eating, mottling, apnea, GI symptoms, fever, anorexia, fevrile URI, acute laryngotracheobronchitis, bronchititis, and febriel convulsions

Question 19

Treatment of influenza with drugs

Answer 19

matrix protein inhibitors (only if susceptible), and euraminidase inhibitors (only if susceptible)

Question 20

What are the 2 types of licensed seasonal influenza vaccines?

Answer 20

1) Inactivated influenza vaccine (injectable, killed vaccine) 2) Live attenuated influenza vaccine (intranasally)

Question 21

What can you say about the influenza stains in both vaccines?

Answer 21

They both have the same 3 strains of influenza, and the quadrivalent vaccine contains the same 2nd B strain. Reformulated annually to provide best protection for anticipated strains.

Question 22

Whats a “well-matched year”?

Answer 22

When the vaccine strain are guessed correctly and provide protection

Question 23

Whats a “mismatched year”

Answer 23

When the vaccine strain are guessed incorrectly and don’t do shit.

Question 24

Efficacy of TIV/IIV (inactivated vaccine)

Answer 24

70% effecting in preventing influenza. Declines in elderly (30-40%) a 50-60% hospitalization and 80% mortality reduction is seen in elderly.

Question 25

Efficacy of LAIV (FluMist)

Answer 25

more efficatious in children < 5 years of age, especially in mismatched years.

Question 26

Describe who gets the IIV and what it is

Answer 26

has 3 or 4 strains, killed, IM, >6 months of age, (+) pregnancy, (+) immunocompromised.

Question 27

Describe who gets the LAIV and what it is

Answer 27

4 strains, live, intranasal, 2-49 years of age, (-) pregnancy, (-) immunocompromised, costs a bit more

Question 28

Who can’t get vaccinated and how do we protect them?

Answer 28

infants <6 months. Herd immunity, vaccinate the mom

Question 29

When and where was “swine flu” discovered?

Answer 29

April 2009 in Mexico was the first case. Was typed in CA

Question 30

Who had the highest rates of 2009 H1N1?

Answer 30

children and young adults <24 years of age.

Question 31

In whom was 2009 H1N1 less common and why?

Answer 31

older than 65 years. Likely similar to influenza circulating prior to 1957

Question 32

What is the current highly virulent strain of avian flu?

Answer 32

H5N1. outbreak on a goose farm in China. It is also known as HPAI H5N1

Question 33

Who is mostly HPAI H5N1

Answer 33

birds and they die from it. But humans can get it too sometimes

Question 34

Whats the primary risk for infection of H5N1?

Answer 34

close contact to infected birds, but human transfer is quite low.

Question 35

Why is it hard to be infected by HPAI H5N1?

Answer 35

Avian virus binds in analpha 2,3 linkage, human virus binds in an alpha 2,6 linkage. Can mutate to bind in alpha 2,6 linkage. This happened before with the 1918 influenza that killed loads of people

Question 36

How else could avian influenza become pandemic besides mutation?

Answer 36

reassortment just like with H1N1

Question 37

What 3 conditions must be met to define when an influenza pandemic is occuring?

Answer 37

1) emergence of a new influenza subtype. 2) virus must infect humans and cause serious illness. 3) virus must have sustained human-to-human transmission and spread easily (without interuption) amoung humans