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Bio 3021 Infectious Disease & Society > Measles-Small Pox > Flashcards

Measles-Small Pox Flashcards

1
Q

Historical Perspective

A

In ancient times, measles often confused with other skin diseases, especially smallpox

First identification of measles as distinct disease separate from smallpox was made in 10th Century A.D.

Distinction between measles and smallpox was then lost for several centuries

Distinction again made in 17th Century

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2
Q

Measles resembles….

A

The Plague

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3
Q

How does measles resemble the plague

A

due to a rash common to both diseases

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4
Q

Measles is caused by what type of virus?

A

enveloped RNA-containing virus

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5
Q

What virus causes measles?

A

paramyxovirus

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6
Q

What is the meaning of paramyxovirus?

A

para(alternate)
myxa(mucus)
virions bind to mucoproteins

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7
Q

Virion components of Measles?

A

Envelope derived from plasma membrane
Coiled helical nucleocapsid
Diameter 150 - 300 nm (filaments

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8
Q

Genome components of Measles?

A

Linear single stranded RNA (negative sense)

single segment

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9
Q

(3) genus of the subfamily paramyxovirinae?

A

paramyxovirus
Rubulavirus
morbillivirus

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10
Q

(1) genus of the subfamily pneumovirinae?

A

pneumovirus

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11
Q

The clinical disease caused by measles virus is known as…

A

rubeola

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12
Q

How is measles transmitted?

A

Respiratory Route via respiratory droplets

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13
Q

Where does initial site of infection occur for measles? Incubation?

A

epithelial cells of the respiratory tract

9 to 11 days

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14
Q

What are the clinical symptoms of measles?

A

sudden onset of sneezing, congestion, cough, rapidly increasing fever, redness of the eyes, and photophobia

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15
Q

Where does the virus spread during measles?

A

local lymph nodes and into the blood where a viremia is established in macrophages

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16
Q

Koplik spots

A

tiny bluish white spots on a red base that appear within the mouth within 2 to 4 days after infection

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17
Q

What part of the skin does the virus infect?

A

endothelial cells of small blood vessels

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18
Q

(3)What does the skin rash indicate?

A

Onset of rash coincides with appearance of cellular immunity
Rash is due to action of CD4+ DTH cells that recognize virus-infected endothelial cells
Destruction of virus-infected endothelial cells results in tiny hemorrhages that appear under the skin resulting in rash characteristic of measles

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19
Q

What is the pathogenesis for the rash during measles?

A

appears first on forehead and behind ears
within 24-48 hours; spreads to face, neck, trunk, and limbs
persists for next 10 days
recovery accompanied by life- long immunity to re-infection

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20
Q

What does SSPE stand for?

A

Subacute Sclerosing Panencephalitis

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21
Q

What is unique about multiple sclerosis?

A

it has a unique north-south geographical gradient

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22
Q

Upon migration studies what can you infer about multiple sclerosis?

A

migration prior to 15 years of age- same risk as native born

migration after 15 years of age- same risk as birthplace

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23
Q

What type of vaccines were licensed in the US in 1963?

A

both killed & live attenuated measles

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24
Q

Why was the formalin-fixed killed vaccine withdrawn from the market?

A

recognition of “atypical” measles in recipients associated with encephalitis

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25
Why was live attenuated Edmonston B vaccine withdrawn?
High rate of fever and rash in recipients
26
Which vaccine is used today for measles?
moraten vaccine which was developed from Edmonston B vaccine strain
27
MMR vaccine
3 live attenuated viruses for immunization against measles, mumps, and rubella
28
When is MMR first administered? second?
between ages of 12-15 months; at childhood before starting school
29
When is MMR contraindicated?
Defects in cellular immunity (HIV/AIDS) and in pregnant women
30
(4) Outcome of MMR vaccine
The incidence of measles has fallen sharply in the United States after immunization was introduced Measles-associated encephalitis occurs at the same rate as nonvaccinated persons Subacute sclerosing panencephalitis (SSPE) is reduced by a factor of 10 in vaccinated persons Possible effect on incidence of multiple sclerosis unknown
31
Why could measles be eradicated from the world? How?
aggressive vaccination program | MMR vaccine contributes to autism has resulted in an increase in the incidence of measles in the UK
32
Smallpox has been known as what type of disease for 2000 years?
generalized severe human disease
33
Who spread smallpox?
though Europe from 1096-1291 AD with crusaders returning & spainards spread the disease to central america
34
What virus causes smallpox?
poxvirus
35
Meaning behind poxvirus..
pox (pocks) | referring to blistering skin lesions
36
(4) Virion components of Smallpox?
complex, ovoid or brick shaped largest known animal virus surface tubules internal core & lateral bodies
37
Genome components of Smallpox?
linear double-stranded DNA molecule
38
(4) Distinctive Characteristics of Poxvirus?
Unusually large and complex virus DNA genome replicates in cytoplasm using exclusively virus-coded enzymes Replicates in cytoplasmic factories of the cell Internal envelope not formed by budding but assembled de novo
39
Reservoir Hosts for the following virus; | Variola, Vaccinia, Cowpox, Monkey pox?
Humans Unknown Rodents Humans, Monkeys & Squirrels
40
Variola Major
classic disease of ancient times | mortality rate of 10% to 30%
41
Variola Minor
less severe form of smallpox | mortality rate of ~1%`
42
Who are the only natural hosts for smallpox?
Humans
43
Transmission of smallpox?
aerosols face-to-face contact via vesicles fomites (bedding & clothing)
44
During SSPE what happens at the age between 8-10 years old?
onset of neurologic disease
45
Pathogenesis of smallpox?
1. infection of the oropharynx via infected aerosols, virus spreads to lymph nodes 2. Asymptomatic primary viremia via infected macrophages occurs on day 3 or 4 after infection 3. Virus spreads to spleen, bone marrow, other lymph nodes, and small blood vessels of the skin and oropharngeal mucosa 4. A secondary viremia occurs by day 8 to 12 after primary infection, followed by onset of clinical signs and symptoms 5. Vesicles on skin and oropharynx appear at about day 14
46
What distinguishes smallpox from chickenpox?
papules that become vesicles filled with thick opaque fluid that contain virus
47
(2) Although death is unclear for smallpox what may be involved?
Multiple organ failure due to immunopathogenesis and/or over- whelming viremia and soluble virus antigens Secondary bacterial infection and sepsis
48
Origin of smallpox vaccine?
Edward Jenner observed that milkmaids who contracted cowpox appeared resistant to smallpox infection
49
COWPOX+ VARIOLA=
vaccinia
50
Rash formation in smallpox?
macules> papules>vesicles
51
Vaccine used against smallpox?
vaccinia
52
Vaccinia has the high rates of what?
adverse reactions
53
In 1958, the WHO embarked on a program for worldwide...
eradication of smallpox
54
When did WHO declare smallpox was eradicated?
1977
55
In 1977, what happened?
Smallpox virus escaped from a lab in England causing the death of a photographer who worked above the lab
56
(2) Known repositories of smallpox in the world?
CDC, Atlanta | State Research Center of Virology & Biotechnology, Russia
57
Smallpox genome can be used for
introduction of foreign genetic materials; bioterrorism (Ebolavirus)
58
(3) Pros to destroy lab virus smallpox?
Must prevent accidental release of virus from two isolation facilities Must prevent terrorists from acquiring virus as an agent of biological warfare The entire genome has been sequenced and sequences now exist in plasmids for study
59
(3) Cons to destroy lab virus smallpox?
We may need a reference virus if smallpox reappears (monkeypox?) The complete virus is needed for studying in detail its pathogenesis at the molecular level We do not have the right to destroy a life-form and cause extinction of the smallpox virus
60
(5) Conclusions regarding smallpox?
``` there is herd immunity an effective vaccine has been available there are no carriers or carrier states pts are most infectious for only a short time after clinical symptoms appear can be diagnosed w/o lab test ```

Bio 3021 Infectious Disease & Society (4 decks)

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