skin 4: smallpox

Question 1

smallpox (Variola major) is ??

Answer 1

A large dsDNA virus that replicates in the cytoplasm of infected human cells.

Question 2

Variola major belongs to ??

Answer 2

Orthopox virus group that includes:
Vaccina
Cowpox
Monkeypox viruses

Question 3

Variola major morality ??

Answer 3

30%

Question 4

Reasons why smallpox was eliminated:

Answer 4

Humans are the only host and sole reservoir.
There is no carrier state (no persistently infected but asymptomatic individuals).
Readily recognizable with only a rare subclinical case
Long incubation – vaccination can protect contacts of infected
Highly effective vaccine

Question 5

variola virus is transmitted:

Answer 5

• Via respiratory droplets: talking, coughing and sneezing
• From skin lesions to mucosa –rarely intact skin
• Fomites, i.e., clothes or bed linens of person with smallpox.
• During prodromal period but less efficiently than during the exanthem

Question 6

variola major spreads quickly or slowly ??

Answer 6

Spreads slowly within a community. Primary attack rate- 20 and 40% but has been shown to vary between 2 and 80%. Variations depend on
Severity of the index case
Population density
Susceptibility of the community as a whole

Question 7

variola major may be contagious even before ??

Answer 7

s/s appear. Persons are contagious until all lesions have healed (pox have separated and fallen off)

Question 8

Clinical manifestations smallpox: there are multiple forms but ?? is the most common

Answer 8

Variola major is the most common form of smallpox.

Question 9

Variola incubation is ??
During this period, there is replication of the virus in the ??
followed by spread to the ??

once replication occurs here, there is a ??

Answer 9

7-17 days
respiratory mucosa
draining lymph nodes.

minor viremia in
which the virus spreads to the liver, spleen, lung, bone marrow, etc.

Question 10

Once replication occurs in the organs, there is a ?? with seeding of the skin with virus during this phase.

Answer 10

major viremia

Question 11

The smallpox major viremia gives rise to an acute onset days of prodromal symptoms during which, the pt. may be infectious:

Answer 11

high fever (40oC / 104oF) with chills
severe headache
back pain
delirium
prostration

Question 12

The fever may wanes after 2-4 days and the ?? begins to appear as the fever declines.
There is often an ?? one or two days before the appearance of the 1st?

Answer 12

exanthem

enanthem

The smallpox exanthem and enanthem are painful!

Question 13

smallpox enanthem/exanthem

Answer 13

enanthem: over tongue, mouth and oropharynx
exanthem: centrifugal pattern first appears on first on the face, concentrated on extremities, palms of the hands and soles of the feet.
Rash progresses from macules to papules, then vesicles, then pustules to scabs (Pustules will umbilicate)
Lesions (pox) are in the same stage of development are deep within the dermis. It may take 8-13 days before scabbing occurs.
Patient is contagious until all scabs separate fall off!

Question 14

other smallpox virus associated symptoms

Answer 14

Pneumonia or pneumonitis – enanthem in lungs

Vomiting – enanthem in g.i. tract.

Question 15

smallpox complications

Answer 15

arthritis in children; variola keratitis, encephalitis, Secondary bacterial infection and/or bacterial superinfection of skin or respiratory tract (bacterial pneumonia)

Question 16

smallpox immunity

Answer 16

T-cell and antibody

Question 17

smallpox dx

Answer 17

clinical presentation. There are several lab tests but most do not distinguish between smallpox and other orthopoxviruses.

• The presence of eosinophilic intracytoplasmic inclusions (Guarnieri bodies) on smears and biopsies of lesion material or black intracytoplasmic inclusions on silver stains may confirm the clinical diagnosis.
• PCR (experimental)
• Electron microscopy
• Immunodiffusion (gel) tests.

Question 18

smallpox tx

Answer 18

Cidofovir (Vistidetm) is a nucleoside phosphonate DNA polymerase inhibitor.

Question 19

smallpox ppx

Answer 19

the smallpox vaccine - vaccina virus vaccine.
Can be administered both pre- exposure and, if provided in a timely fashion, post-exposure
The basis for its protection is that there is a high degree of antigenic similarity (cross-reactivity) between it and the smallpox virus

Question 20

smallpox vaccine

Answer 20

Multiple vaccine preps available and in development. Not a benign vaccine

Administered with a bifurcated needle using scarification. Three stabs to nonimmune (not
previously immunized) and 15 stabs to immune (previously immunized) individuals.

Question 21

“normal” responses to smallpox (vaccina) vaccine

Answer 21

Local infection and lesion formation - scar.
Other “Normal”responses:
Pustular lesion at the injection site leaving a depigmented scar
Flu-like symptoms of fever, malaise, headache, etc.
Regional lymphadenopathy
Satellite lesions

Question 22

Adverse side effects of the vaccina vaccines:

Answer 22

-Est. 1,250 persons/million vaccinated will have an adverse reaction: 1 person/million vaccinated will die of some side effect.
-Progressive vaccina or vaccina gangrenosa – very rare necrotic
manifestation in individuals with occult immunosuppression.
-Eczema vaccinatum - local or systemic infection in persons with a history of eczema.
-Vaccina encephalitis
-Recent vaccination has yielded evidence of pericardiomyopathy
-The immunosuppressed & unvaccinated persons inadvertently infected by
vaccinated persons are at higher risk for adverse reactions.
-Most adverse reactions are due to autoinoculation (e.g. eye) and can be prevented by education while others can be prevented by rigorous screening and exclusion criteria.

Question 23

with all the complications, should we use vaccina virus vaccine ??
and if yes, for whom ??

Answer 23

regardless of potential adverse reactions, it is recommended that all persons exposed to a known source of smallpox (e.g. infected patient) should be vaccinated.

Question 24

It is estimated that solid protection lasts ?? following immunization and partial immunity (infection possible but with significantly modified disease course) is assured within ??

Some indication that vaccination at any point in life is likely to provide at least some partial immunity??

Answer 24

3 to 5 years
10 years

3% vs. 30% mortality rate!

Question 25

variola vs. varicella: incubation period

Answer 25

small: 7-17 days
chicken: 14-21 days

Question 26

variola vs. varicella: prodrome

Answer 26

smallpox: 2-4 days

chicken pox: Minimal if present (adults and adolescents)

Question 27

variola vs. varicella: distribution

Answer 27

smallpox: centrifugal

chicken pox: centripetal

Question 28

variola vs. varicella: palms and soles?

Answer 28

smallpox: YES

chicken pox: NO

Question 29

variola vs. varicella: evolution

Answer 29

smallpox: synchronous

chicken pox: asynchronous

Question 30

variola vs. varicella: pock penetration

Answer 30

smallpox: deep dermis

chicken pox: superficial

Question 31

variola vs. varicella: scabs form in ??

Answer 31

smallpox: 10-14 days

chicken pox: 4-7 days

Question 32

variola vs. varicella: scabs separate in ??

Answer 32

smallpox: 14-28 days

chicken pox: less than 14 days

Question 33

variola vs. varicella: no longer contagious when ??

Answer 33

smallpox: after separation of scabs

chicken pox: after scabbing