3. The Organism
# Caused by Variola virus
# Double stranded DNA virus
# Genus: Orthopoxvirus
# Variola major or minor
# Stable outside host(retains infectivity)
4. Microbiology
Variola major
– Classic smallpox
– Predominant form in Asian epidemics
– Highest mortality (~30%)
Variola minor
– Causes milder disease
– Discovered in 20th century
– Started in S. Africa
– Was most predominant form in N. America
5. Microbiology continues
• All ages and genders affected
• Incubation period
• From infection to onset of prodrome
• Range 7-17 days
• Mortality
• 30% overall in unvaccinated population
• Infants, elderly greatest risk (>40%)
• Dependent on virus strain
• Dependent on disease variant
6.
7. First Case of Smallpox
No animal reservoir and no
human carriers.
First certain evidence comes
from the mummified remains
of Ramses(1157 B.C.).
8. Pathophysiology
Virus lands on respiratory/oral mucosa
Macrophages carry to regional nodes
Invades reticuloendothelial organs
White Blood Cells infected
Systemic inflammatory response
9. Stages of Smallpox
Three stages of disease:
• 1. Incubation
• Asymptomatic
• 2. Prodromal
• Nonspecific febrile illness,
flu-like
• 3. Eruptive
• Characteristic rash
13. Symptoms & Signs
• The first symptoms of smallpox usually appear
12 to 14 days after you're infected.
• During the incubation period of seven to 17
days, you look and feel healthy and can't
infect others.
16. Diagnosis
• Physical examination and blood
tests. Fever and the distinctive,
progressive skin rash will indicate
smallpox.
• Smallpox and monkeypox virions
may be indistinguishable.
17. Prevention
• The smallpox vaccine is the only known way to
prevent smallpox in an exposed person. The smallpox
vaccine helps the body develop immunity to
smallpox.
18. Treatment
Variolation
• Inoculation with infectious smallpox
• Scabs or pustular material
• 3% mortality
• Immunized were infectious - outbreaks
• Provided full immunity
• Originated in Eastern countries in ancient
times
• Started in U.S. by Rev. Cotton Mather 1721
19. Vaccination
Edward
Jenner
develops
vaccine
1796
Freeze-dying
technolog
y
1940’s
Licensure
of
bifurcate
d needle
1965
Attenuated
1975 strains
Vaccine
removed
from
civilian
market
1983
20. Vaccine Administration
Jet gun
• Rapid
• High maintenance
Bifurcated needle
• High efficacy, sterilizable, rapid
(1500/day)
• Uses less vaccine
• Mainstay for the WHO
eradication campaign
23. • Exposure to a case
patient after fever
onset
• Contact with
secretions or
• Face-to-face contact or
• In nosocomial setting
with a case
• Includes all hospital
patients and staff
Carefully
identify
true
contacts:-
Management of Case Contacts
24. Outbreak Management
Contact to Contact
Contact to Case
Case
Fig: Ring vaccination
Strategy
in
outbreak
• All confirmed or
suspected cases
• All contacts of
confirmed/suspected
cases
• All hospital
personnel of
hospitalized cases
• All other patients in
hospital with cases
27. The End of Smallpox
• Oct 26, 1977, last case of smallpox.
• May 8, 1980, official declaration by WHO - Smallpox
Eradicated!
Last case
of Variola
minor,
Somalia
1977
Last case of
Variola
major,
Bangladesh
1975
28. Factors That Allowed Smallpox
Slow spread
Effective,
relatively safe
vaccine
No
animal/insect
vectors
International
cooperation
Prior infection
gives lifelong
immunity
Infectious
only with
symptoms
Eradication
29. Variola viruses
do not exist in
nature.
Some nations are
suspected of
having active
bioweapons
programs.
North Korea
Syria
Iran
Israel
Russia
Some may have
kept smallpox
stocks hidden.
The world is ill-prepared
for
smallpox.
Vaccination is
no longer
routine.
Thus, a large
susceptible
population.
Smallpox as a Biological Weapon
