Habal: Influenza and Pertussis

Question 1

What is the most common season for flu in temperate areas? In tropical regions?

Answer 1

Winter; year-round

Question 2

What type of virus is influenza?

Answer 2

Orthomyxoviridae, -ssRNA, segmented

Question 3

What is the problem with RNA viruses, and even more so with segmented RNA viruses?

Answer 3

RNA is more prone to mutations during replication because it lacks DNApol. So it’s hard to make a vaccine. This is even more so the case with segmented RNA viruses.

Question 4

Which type of influenza is most virulent?

Answer 4

Influenza A (infects humans, birds, swine, etc)

Question 5

Which influenza is only found in humans?

Answer 5

Influenza B (mild)

Question 6

What virulence factor in influenza facilitates attachment to siacilic acid?

Answer 6

Hemagglutinin

Question 7

What virulence factor in influenza cleaves sialacic acid residue and promotes entry of the virus into the cell?

Answer 7

Neuraminidase (Sialidase)

Question 8

Is Antigenic Drift or Antigenic Shift responsible for new yearly strains?

Answer 8

Drift

Question 9

What is the difference between drift and shift?

Answer 9

Antigenic drift: small, constant point mutations; leads to EPIDEMICS; seen in all 3 types.

Antigenic Shift: substation of gene segments from another influenza virus –> REASSORTMENT; only in type A; causes PANDEMICS.

Question 10

Explain what’s in the name of each influenza strain.

Answer 10

Host origin/geographic location of first isolate/strain number/year (hemagglutinin and neuraminidase subtypes)

i.e. A/California/7/2009 (H1N1)

Question 11

What does influenza infect?

Answer 11

respiratory epithelial cells

Question 12

When in the influenza virus no long detected in a patient?

Answer 12

5-10 days after symptoms

Question 13

What is the key clinical manifestation of influenza?

Answer 13

Sudden Rapid Onset

Question 14

Complications of influenza?

Answer 14

PBR!

Pneumonia, Bronchitis, Reye Syndrome

Question 15

Treatment on influenza?

Answer 15

Zanamivir (Relenza), Oseltamivir (Tamiflu): Both target neuroaminidase (works on A, B)

Question 16

What do annual vaccinations of influenza have?

Answer 16

the yearly dominant three strains (2 type A and 1 type B) –> Trivalent vaccine

(**No effect on limiting pandemics)

(inactivated via IM; 6m or older)

Question 17

When does vaccination begin each year?

Answer 17

Oct - Jan

Question 18

Can you get Influenza Type A via person-person contact?

Answer 18

rare; usually from a bird

Question 19

What is the natural host of pertussis?

Answer 19

Humans are the only natural host.

Question 20

How can you culture pertussis?

Answer 20

Bordet-Gengou or Regan-Lowe agars

Question 21

What are the 5 main virulence toxins in pertussis?

Answer 21

1. Polysaccharide capsule
2. Outer membrane protein for adhesion
3. Tracheal cytotoxin that destroys ciliated epithelial cells (causes host cells to make IL-1 –> NO–> death of resp cells –> ciliostatic
4. Filamentous Hemagglutinins (FHA): RBC agglutination. Bacteria attaches to epithelial cells
5. Pertussis AB Toxin

Question 22

Main MOA of Pertussis?

Answer 22

Blocks G(inhibitory) and stimulstes G(stimulatory) –> huge increase in cAMP –> electrolytes and water leave the cell, leading to cell death

PERTUSSIS EXOTOXIN:
INHIBITS: chemotaxis, phagocytosis, superoxide generation
INDUCES: apoptosis in MPs; IgE synthesis

Question 23

What are the 4 stages and characteristics of pertussis?

Answer 23

Incubation (7-10d): no sx.
Catarrhal (1-2w): rhinorrhea, fever
Paroxysmal (2-4w): whooping cough, vomiting, leukocytosis
Convalescent (3-4 w): diminished paroxysmal cough BUT with development of worse vary complications (pneumonia, seizures, encephalopathy)

Question 24

What type of vaccine does the US use?

Answer 24

Acellular (no longer use whole killed cell)

It’s recommended to get Tdap for adults every 10 years instead of just tetanus.