Influenza

Question 1

What is the etiological agent of influenza

Answer 1

Orthomyxovirus

Question 2

Describe the etiological agent of influenza

Answer 2

spherical or filamentous particle, helical nucleocapsid, enveloped, has 6-8 different segments that codes for 1-2 proteins each

Question 3

what does orthomyxovirus mean

Answer 3

Correct mucus, virions bind to mucoproteins

Question 4

what are the distinctive characteristics of influenza virus

Answer 4

replicates in the nucleus, undergoes reassortment by exchanging genome segments b/t strains, and reassortment generates new viruses that cause pandemics due to changed surface antigens

Question 5

How many types of influenza viruses are there

Answer 5

3

Question 6

what are the different types of influenza viruses

Answer 6

Influenza A, B, and C

Question 7

describe Influenza A

Answer 7

Found in humans, swine, avian, equine, and marine mammals. may cause large pandemics. Significant morbidity and mortality

Question 8

Describe Influenza B

Answer 8

Only found in Humans. Not associated with pandemics/ only epidemics. Cause mild disease

Question 9

Describe Influenza C

Answer 9

Found in humans and swine. not associated with pandemics and cause mild disease

Question 10

The major host for Influenza A is what

Answer 10

Wild Ducks

Question 11

Hemagglutinin serves as what in Influenza

Answer 11

It is a major surface antigen that serves as site of attachment to host cell and initiates infection

Question 12

How many HAs have been identified

Answer 12

15 antigenically distinct HAs (H1-H15)

Question 13

what does HA stand for

Answer 13

Hemagglutinin

Question 14

Which HAs have been identified for human influenza A

Answer 14

H1,H2, and H3

Question 15

What purpose does Neuraminidase serve during Influenza

Answer 15

It is a major surface antigen that acts as an enzyme that cleaves sialic acid from glycoproteins

Question 16

What major role does NA play in infection

Answer 16

Is important during the replication (maturation) of virus

Question 17

What does NA stand for

Answer 17

Neuraminidase

Question 18

How many NAs have been identified

Answer 18

9 antigenically distinct NAs

Question 19

Which NAs have been identified for human influenza A

Answer 19

N1 and N2

Question 20

What unique feature of influenza A explains why it causes major epidemic and pandemic diseases in humans

Answer 20

The frequency with which they can change antigenically, Antigenic variation

Question 21

What are the two degrees of an antigenic variation

Answer 21

Drift and shift

Question 22

When there is a small change antigenically, its called

Answer 22

a drift

Question 23

when there is a major change antigenically, its called

Answer 23

a shift

Question 24

Briefly describe an Antigenic Drift

Answer 24

minor changes that occur every year that are associated with variation in HA that cause epidemics. Epidemics occur on avg every 2.4 yrs

Question 25

Briefly describe an Antigenic Shift

Answer 25

Major changes in HA and NA that produce a new virus strain that the population has no herd immunity for and results in pandemic. These are unpredictable but occur every 10 to 12 yrs

Question 26

Describe the genome of Influenza A

Answer 26

consists of 8 distinct segmented pieces of single-stranded RNA. 4 pieces encodes for HA and 6 encodes for NA.

Question 27

How does the new strains or variations occur

Answer 27

When two unrelated viruses infect the same cell, 16 RNA segments are released and genetic reassortment may yield progeny virus

Question 28

How is Influenza transmitted

Answer 28

the virus spreads by respiratory droplets and may be involved in transmission

Question 29

How long can the virus remain infectious in environment

Answer 29

Virus remains infectious for >24 hrs after aerosolization and 1-2 days on hard nonporus surfaces

Question 30

Describe the Pathogenesis of Influenza

Answer 30

Initial site of infections is the respiratory tract mucosa and shedding begins ~1 day before onset of illness which presents abruptly with prominent systemic illness and respiratory syndromes. Virus induced cytopathology and apoptosis contributes to illness. Shedding last 3-7 days. Fever and systemic complaints end on day 7. Slow recovery w/ cough and malaise last for 2-4 weeks

Question 31

What usually causes death with Influenza

Answer 31

Pulmonary complications such as secondary bacterial infection, excessive expression of cytokines (cytokine storm), or excessive hemorrhaging when lungs are more involved and could drown and suffocate

Question 32

How many people die in the US from Influenza

Answer 32

36k each year ranging from 17-52k

Question 33

Influenza is usually associated with a ______ epidemic curve and mortality is generally highest in ________

Answer 33

U-shaped; young and older adults

Question 34

How long does it take Influenza to infect you?

Answer 34

1- 5 days

Question 35

Excess morbidity and mortality are particularly high in who

Answer 35

Those with cardiovascular or pulmonary conditions, chronic metabolic disease, or HIV/AIDS

Question 36

Death rates are as high as __ per year in nursing home residents

Answer 36

2.8%

Question 37

How is Influenza treated

Answer 37

Four antiviral drugs available ; Amantadine, Rimantadine, Zanamivir, and Oseltamivir (Tamaflu)

Question 38

When is the antiviral therapy shown to be non beneficial

Answer 38

after 48 hrs or more after appearance of clinical symptoms

Question 39

When is treatment most beneficial

Answer 39

When its started in the first 24 hrs of clinical symptoms

Question 40

How does amantadine and rimantadine take action

Answer 40

they prevent the uncoating of virus

Question 41

How does zanamivir and oseltamivir take action

Answer 41

they prevent maturation of virus

Question 42

Briefly describe the mechanism of action for Amantadine

Answer 42

It targets the M2 (channel) protein of virus by blocking the entry of H+ inons into virion and thereby prevents the release of RNA/nucleoprotein complexes into cytoplasm

Question 43

briefly describe the mechanism of action for Zanamivir and Oseltamivir

Answer 43

It competes with sialic acid for binding to NA preventing sialic acid cleavage and prevent the release of virus

Question 44

Are there any vaccines for Influenza

Answer 44

There is a Live attenuated vaccine that induces mucosal immune responses (IgA) that closely mimics natural response and a killed vaccine that is grown in chicken eggs and contain influenza subtypes A and B

Question 45

The first epidemic of Influenza was described in _____

Answer 45

Europe in 1510

Question 46

What were the names of Influenza in the 16th Century

Answer 46

the new acquaintance and the gentle correction

Question 47

What were the names of Influenza in the 17th Century

Answer 47

The new delight, the jolly rant, and la grippe

Question 48

What were the names of Influenza in the 18th Century

Answer 48

the influenza and Influenza

Question 49

When did the great influenza Pandemic occur

Answer 49

1918-1919

Question 50

_____ persons died worldwide with a fatality rate of _____ worldwide during the pandemic

Answer 50

20-100 million ; 4-20%

Question 51

Influenza has killed more persons in __ than ____ has killed in ____ and accounted for ___ of US war deaths

Answer 51

one year; HIV/AIDS; 28 years; 80%

Question 52

The Great Influenza Pandemic came in 4 waves which were

Answer 52

1st wave Jan. 1918, 2nd wave Aug. 1918 (most virulent), 3rd wave Dec. 1918, and ended Mar. 1919