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MMI 415 > Eradicating viruses > Flashcards

Eradicating viruses Flashcards

1
Q

What are the animal equivalents of the following viral diseases: smallpox, measles, and polio?

A
  • small pox –> camel pox
  • measles –> rinderpest virus
  • polio –> enteroviruses
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2
Q

what virus causes small pox?

A

variola virus

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3
Q

what are the two forms of smallpox?

A
  • variola major
  • variola minor
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4
Q

how does smallpox spread?

A

aersols and through fomites

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5
Q

describe the disease course of variola major

A
  1. incubation period: 1-2 weeks
  2. prodrome: few days, not very contagious, high fever, malaise, headache
  3. early rash: 4 days, highly infectious, lesions appear all over
  4. pustular rash: 5 days, contagious, lesions become postules
  5. postules and scabs: 5 days, contagious, pustules scab over
  6. resolving scabs: 6 days, contagious, scabs retain some virus
  7. scabs resolve: no longer infectious, scarring
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6
Q

what are the other types of small pox?

A
  • modified smallpox: mild, usually previously vaccinated with poor take, low mortality
  • flat smallpox: severe, sunburn like features, high mortality
  • hemorrhagic smallpox: few lesions, extensive hemorrhagic manifestations, inflammatory shock, 100% lethal

flat and hemorrhagic are probably due to pre-existing immune deficiences including pregnancy

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7
Q

what’s the difference between monkeypox and smallpox?

A
  • smaller mortality
  • fewer lesions
  • differential diagnosis: PCR, serology
  • endemic to central/west africa
  • zoonotic, small rodent reservoir, bushmeat trade
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8
Q

describe the sequelae of smallpox

A
  • pock marks, scarring
  • blindness
  • limb deformities
  • lifelong resistance
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9
Q

describe the biology of variola virus

A
  • poxvirus (orthopoxvirus family)
  • large dsDNA virus
  • encodes immunosuppressive virulence factors
  • large brick-shaped viruses – can be seen under a light microscope
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10
Q

what is the smallest orthopoxvirus?

A

variola virus (VARV)

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11
Q

how has smallpox shaped faith?

A

many religions have gods devoted to smallpox

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12
Q

where did smallpox originate from? what about variola minor?

A
  • possibly Nile valley, fertile crescent, rome’s granary
  • minor: spread from africa to the americas by the slave trade
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13
Q

how did we date the emergence of smallpox?

A

using a molecular clock and DNA from a 370 year old lithuanian mummy

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14
Q

describe the course of smallpox in Peru: 1524

A
  1. 1524: smallpox arrives
  2. 25: smallpox kills the inca, huayna capac, and his heir dies soon afterwards –> civil war
  3. 33: Pizzaro exploits the chaos and brutally conquers the territory
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15
Q

what plagues caused the destruction of central and south american civilization

A
  • smallpox
  • measles
  • typhus
  • influenza
  • yellow fever
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16
Q

what was the Great Dying in Austrailia?

A
  • british colonists brought smallpox on arrival day
  • an endemic ensued
  • children and pregnant women were especially vulnerable
  • waves of disease moved westward over the 19th century, traveleres encountered scarred and blinded survivors
17
Q

how did the great dying cause a little ice age?

A

epidemics killed 100 million people in the 16th-17th century, the forests grow back on abandoned fields –> CO2 was absorbed by the new forests and the world cools

18
Q

what factors favour elimination of smallpox

A
  • cheap, safe, and effective vaccine producing long-lived immunity (no cold chain needed)
  • easily detected/reported
  • no persistent infections or permanent reservoir
19
Q

why did the american campaign against quebec fail?

A
  • british forces were routinely variolated, americans not so
  • american troops got sick and their campaign failed
20
Q

which virus, discovered by Jenner, was ultimately used to eradicate smallpox?

A

vaccinia virus

21
Q

what is the origin of vaccinia virus?

A

likely a horsepox and not a cowpox

22
Q

how and why was Jenner’s vaccine improved upon?

A
  • jenner’s vaccine was originally passaged in humans –> spread other diseases like syphillus
  • vaccine farms arose and “calf lymph” was used throughout the eradication era
23
Q

when was smallpox declared eradicated? how did we achieve eradication?

A
  • 1979
  • world-wide mandatory vaccination campaigns plus aggressive search and discovery tactica
  • late stages: ring vaccination plus bounties for new cases
24
Q

what are practical challenges to vaccination?

A
  • wars
  • corruption
  • incompetence
  • religious and tribal feuds
  • mistrust
  • individual versus community rights
  • poverty
25
Q

what are the special rules for handling variola virus?

A
  • only two sites are allowed to store and study variola virus: BSL4 requirements, archives are stored frozen with armed guards
  • centers must report what they are doing every year to WHO
  • only research relating to drug, vaccine and/or diagnosistic development is allowed
  • no lab can retain clones or DNAs comprising >25% of the genome
  • engineering variola genes into other poxviruses is illegal
  • in canada, possession of variola is a criminal offence under the pathogens and toxins act
26
Q

what are the two labs with variola now?

A

CDC Atlanta, US
VECTOR, Russia

27
Q

what type of virus in rinderpest?

A

(-)ssRNA virus

28
Q

describe the disease caused by rinderpest

A
  • respiratory virus
  • highly contagious
  • causes oozing sores in the mouth, eyes, respiratory, and urogenital tracts
  • symptoms include diarrhea, dehydration and death
  • young animals are the most sensitive and immune for life
  • affects cattle, sheep, goats, and wild game
  • 90% mortality
29
Q

why was it feasible to eradicate rinderpest?

A
  • vaccine protects from all three lineages
  • Ro was lowerish, so herd immunity suffices
  • high impact disease –> encourages cooperation
30
Q

what was the original method used in europe to control rinderpest?

A

mass slaughter

31
Q

what were the special tactics used to help eliminate rinderpest?

A
  • PCR helped track origins of outbreaks
  • serological testing measured vaccination and infection rates
  • isolated reservoirs in ethiopia, sudan, yemen, pakistan and india were picked as priority targets
  • UNICEF partnership helped recruit community liason officers – trained as vaccinators and vets, gaining trust and providing access to confict zones
32
Q

when was rinderpest declared eradicated it, what were some challenges to eliminating it?

A
  • 2011
  • wildlife reservoirs
  • mistrust
  • tribal feuds
  • wars
  • poverty
33
Q

where is rinderpest being held now?

A
  • AU-PANVAC, ethiopia
  • National institute of animal health, japan
34
Q

describe some general featurs of poliovirus: disease, family, route of transmission. who’s at risk, seuquelae

A
  • causes poliomyelitis
  • picornaviridae
  • oral-fecal route
  • can estabilsh carrier stages
  • children under 5 are at greatest risk
  • can cause permanent paralysis
35
Q

what are the two polio vaccines?

A
  • sabin: live attenuated, oral vax
  • salk: killed injectable vax
36
Q

what polio strains are circulating today, which is the major one?

A
  • wt
  • cVDPV1
  • cVDPV2 (most)
37
Q

how many mutations are requred to create a cVDPV2 polio strain, how long does this take?

A

6 mutations –> about a year

38
Q

what recent change to the polio vaccine makes it much harder for it to revert?

A

CpG codons were used to replace synonymous codons in the capsid genes + 5’UTR was altered –> makes it hard to revert

39
Q

what is the next virus we are looking to eliminate?

A

peste des petite ruminants (PPR)

MMI 415 (13 decks)

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