Poliomyelitis: 10.26.2022. study questions

Question 1

what is the structure of the polio virus? (4)

Answer 1

Icosahedral, nkd, ss+RNA
(enterovirus)

Question 2

true or false: most polio virus infections are asymptomatic or mild

Answer 2

true

Question 3

when does paralytic polio occur?

Answer 3

when a vaccine strain of OPV can mutate to become virulent

Question 4

what are the two types of vaccines to prevent polio?

Answer 4

• OPV
• IPV

Question 5

what does the term VDPV mean? when does it occur?

Answer 5

vaccine-derived poliovirus. this is what happens when a strain of OPV mutates, resulting in vaccine-associated paralytic polio

Question 6

why is OPV crucial for eradication of polio?

Answer 6

to eradicate polio, OPV must be used in regions where the virus in endemic (present) or likely to be reintroduced.

why?

OPV prevents the spread of poliovirus in a population.

prevents reintroduced poliovirus from spreading within the population.

IPV protects people from paralytic poliomyelitis, but does not prevent reintroduced poliovirus from spreading within the population.

Question 7

how does polio virus cause disease?

Answer 7

• enters the body orally
• infects cells that line the throat and IT tract
• then invades the bloodstream
• rarely enters the CNS

Question 8

what does it mean in terms of infections if you see a single case of paralytic polio?

Answer 8

lots of people are infected but not infectious, because it spreads like crazy and 99% of people don’t get sick or have mild symptoms

Question 10

what two types of vaccines are available for polio?

Answer 10

• OPV: oral polio vaccine
• IPV: inactivated polio vaccine

Question 11

pros (3) and cons of OPV

Answer 11

PROS:
- replicate in the recipient’s intestinal tract and are excreted in feces, and can thereby spread to others, immunizing them as well
- less expensive to produce than IPV
- easier to administer because it does not require an injection

CONS:
- vaccine strain can mutate to become virulent, resulting in vaccine-associated paralytic polio

Question 12

pros and cons of IPV

Answer 12

PROS:
- trivalent, so it protects against any type 2 VDPV that might still be circulating

CONS:
- unreliable at eliciting the production of mucosal antibodies

Question 14

which polio vaccine is attenuated?

Answer 14

OPV

Question 15

what does it mean about the prevalence of polio if you see cases of paralytic polio?

Answer 15

lots of people have it and are infectious/spreading it

Question 16

how does good sanitation play a role in polio eradication?

Answer 16

the viral particles can be inactivated by pasteurization and by chlorinating drinking water

Question 18

what is OPV?
what does it contain?
how does it work?

Answer 18

oral polio vaccine.
contains attenuated poliovirus and can be administered as drops on the tongue

Question 19

what is IPV? How is it administered?

Answer 19

inactivated polio vaccine.
given by injection

Question 20

how does OPV help in herd immunity or why was OPV instrumental in eradicating polio? compared to IPV?

Answer 20

when someone who’s received the OPV vaccine ingests poliovirus-contaminated material, mucosal antibodies in the GI tract neutralize the viral particles before they can infect cells and replicate. IPV is unreliable at eliciting the production of mucosal antibodies.

Question 21

why do we use IPV only in the US?

Answer 21

VDPV –> cases of polio in the US

Question 22

what is WPV?

Answer 22

wild poliovirus

Question 23

what does trivalent mean?
it contains all three what?

Answer 23

a polio vaccine that contains all three poliovirus serotypes

Question 24

OPV used to be trivalent. what happened?

Answer 24

type two was eradicated, so the trivalent vaccine was replaced by a bivalent OPV (bOPV) that contains only types 1 and 3. monovalent options against those types are also available.

Question 25

why was the removal of poliovirus type 2 from OPV significant?

Answer 25

most vaccine-associated illness was due to the type

Question 26

what is the characteristic feature of poliomyelitis? what does that result in?

Answer 26

destruction of motor neurons, resulting in paralysis of a group of muscles, such as a heart or leg