Smallpox

Question 1

During the 17th and 18th centuries, how many people died of smallpox

Answer 1

~400,000 annually

Question 2

What is the etiological agent of Smallpox

Answer 2

poxvirus

Question 3

describe the etiological agent of smallpox

Answer 3

Complex and brick shaped, the largest known animal virus, linear double stranded DNA that encodes for 150-250 different proteins

Question 4

what are the distinctive characteristics of the poxvirus

Answer 4

Usually large and complex, DNA genome replicates in cytoplasm using only virus-coded enzymes, replicates in cytoplasmic factories of the cell, and internal envelope not formed by budding but assembled de novo.

Question 5

What is smallpox also known as

Answer 5

Variola Virus

Question 6

Variola Major, classic disease of ancient times, has a mortality rate of ___

Answer 6

10%-30%

Question 7

Variol Minor, the less severe form of smallpox, has a mortality rate of __

Answer 7

~1%

Question 8

How is small pox transmitted

Answer 8

Humans being the only natural host, it can be transmitted by aerosols, physical contact with vesicles, or fomites (bedding or clothing)

Question 9

Describe the pathogenesis of smallpox

Answer 9

Infection of oropharynx via infected aerosols and spreads to regional lymph nodes. An asymptomatic primary viremia via infected macrophages. Virus spreads to spleen, bone marrow, other lymph nodes, and small blood vessels of skin and oropharngeal mucosa. A secondary viremia occurs followed by onset of clinical signs and symptoms, vesicles on skin and oropharynx.

Question 10

About when does the asymptomatic primary viremia occurs

Answer 10

3-4 days after primary infection

Question 11

____ occurs by day 8-12 after primary infection

Answer 11

Secondary viremia

Question 12

When do you normally start to see vesicles form on skin

Answer 12

day 14

Question 13

What is the incubation time for smallpox

Answer 13

12-14 days on average but can range from 7-17 days

Question 14

what is used to distinguish smallpox from other rash illnesses

Answer 14

smallpox has a prodrome phase that appears before onset of rash and lasts 2-4 days.

Question 15

what happens during the prodrome phase

Answer 15

abrupt fever (>101F) headache, nausea, vomiting, and malaise

Question 16

During what time of clinical disease is a person most infectious

Answer 16

during the time there are small red spots on tongue and mouth which ulcerate and release large amounts of virus into saliva.

Question 17

How long does the most infectious stage last

Answer 17

4 days

Question 18

when does the most infectious stage begin

Answer 18

~24 before onset of rash on skin

Question 19

How does the rash spread on the body

Answer 19

in a centrifuge distribution, outward in.

Question 20

what is the clinical progression of disease

Answer 20

by the 3rd day the macules become papules. Then the 4th day the papules become vesicles filled with thick opaque fluid that contains infectious virus. Fever rises again and remains high until scabs from on vesicles to form pustules. Pustules are raised, round, firm to the touch and mature and reach maximum size by 7th-10th day. By day 10 the pustules begin to crust over and scab at the 14th day.

Question 21

how are smallpox distinguished from chickenpox

Answer 21

Smallpox vesicles have a depression in the center, umbilication.

Question 22

why does smallpox lesions have depimentation and pitted scars

Answer 22

because the sebaceous gland (sweat glad) of the skin has been destroyed

Question 23

what is the suspected cause of death in smallpox and when does it usually occur

Answer 23

It’s suspected multiple organ failure due to immunopathogenesis or over whelming viremia and secondary bacterial infections and sepsis; 10-16 weeks of clinical illness

Question 24

the small pox vaccine virus is termed

Answer 24

vaccinia

Question 25

What is vaccinia

Answer 25

it’s a hybrid virus that arose from inadvertent mixing of cowpox virus and variola virus.

Question 26

Why is smallpox called “The Honorable Gentleman”

Answer 26

The symptoms are obvious so it can be diagnosed without lab test. Patients are only most infectious for a short time. there are not carriers or carrier states. An effective vaccine has been developed for >150 years and there is herd immunity

Question 27

When did the World Health Organization declare smallpox eradicated from the world

Answer 27

1977

Question 28

Where are the two known places smallpox is kept

Answer 28

The CDC in Atlanta and State Research of Center of Virology and Biotech Siberia, Russia

Question 29

What are some pros for destroying the smallpox virus.

Answer 29

Must prevent accidental release of virus. Must prevent terrorists from acquiring virus as a biological weapon. The entire genome has been sequenced and exist in plasmids to study

Question 30

What are some cons for destroying the smallpox virus

Answer 30

we may need a reference if smallpox reappears. 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