Poliomyelitis: 10.26.2022. study questions Flashcards
what is the structure of the polio virus? (4)
Icosahedral, nkd, ss+RNA
(enterovirus)
true or false: most polio virus infections are asymptomatic or mild
true
when does paralytic polio occur?
when a vaccine strain of OPV can mutate to become virulent
what are the two types of vaccines to prevent polio?
- OPV
- IPV
what does the term VDPV mean? when does it occur?
vaccine-derived poliovirus. this is what happens when a strain of OPV mutates, resulting in vaccine-associated paralytic polio
why is OPV crucial for eradication of polio?
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.
how does polio virus cause disease?
- enters the body orally
- infects cells that line the throat and IT tract
- then invades the bloodstream
- rarely enters the CNS
what does it mean in terms of infections if you see a single case of paralytic polio?
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
what two types of vaccines are available for polio?
- OPV: oral polio vaccine
- IPV: inactivated polio vaccine
pros (3) and cons of OPV
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
pros and cons of IPV
PROS:
- trivalent, so it protects against any type 2 VDPV that might still be circulating
CONS:
- unreliable at eliciting the production of mucosal antibodies
which polio vaccine is attenuated?
OPV
what does it mean about the prevalence of polio if you see cases of paralytic polio?
lots of people have it and are infectious/spreading it
how does good sanitation play a role in polio eradication?
the viral particles can be inactivated by pasteurization and by chlorinating drinking water
what is OPV?
what does it contain?
how does it work?
oral polio vaccine.
contains attenuated poliovirus and can be administered as drops on the tongue
what is IPV? How is it administered?
inactivated polio vaccine.
given by injection
how does OPV help in herd immunity or why was OPV instrumental in eradicating polio? compared to IPV?
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.
why do we use IPV only in the US?
VDPV –> cases of polio in the US
what is WPV?
wild poliovirus
what does trivalent mean?
it contains all three what?
a polio vaccine that contains all three poliovirus serotypes
OPV used to be trivalent. what happened?
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.
why was the removal of poliovirus type 2 from OPV significant?
most vaccine-associated illness was due to the type
what is the characteristic feature of poliomyelitis? what does that result in?
destruction of motor neurons, resulting in paralysis of a group of muscles, such as a heart or leg
