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Lecture 6

HLTB21H3 Lecture Notes - Lecture 6: Smallpox, Orthopoxvirus, Ramesses V


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat
Lecture
6

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Disease Origins
-Believed to have appeared around 10,000BC, at the time of the first agricultural settlements in
NE Africa and spread to India by means of ancient Egyptian merchants
-Earliest evidence of skin lesions resembling those of smallpox on Egyptian mummies (1570 -
1085 BC)
-The mummified head of the Egyptian pharaoh Ramses V (died 1156 BC) bears evidence of teh
disease
-Concurrently, smallpox has been reported in ancient Asian cultures, described 1122 BC in
China and is mentioned in ancient texts of India
-Introduced to Europe between the fifth and seventh centuries and was frequently epidemic
during the Middle ages
Effects of Smallpox
-plague of Antonine - decline of the Roman Empire (AD 108)
-Introduction by the Spanish and Portugese led to the decimation of the local population and
was instrumental in the fall of the empire of the Aztees and the Incas
-Eastern coast of North America. the disease was introduced by the early settlers and led to a
decline in the native population
-Biological warfare
-French-indian war (1754-1767)
-Commander of the British forces in North America (Amherst), suggested the deliberate use of
smallpox to diminish the American Indian population hostile to the British
-Slave trade also contributed to the spread of smallpox in N. America
Etiology
-Genus - Orthopoxvirus, family Poxviridae
-Common name - Variola virus
-At least 2 strains exist: variola major (more virulent) and variola minor
-The Orthopoxvirus genus also include the monkeypox, cowpox, camelpox, chickenpox, and
ectromelia (mousepox) viruses
-Variola minor is a milder disease - mortality rate is approximately 1% in unvaccinated person
-Overall mortality rate for variola major is 3% in vaccinated individuals and 30% in
unvaccinated
-Malignant and hemorrhagic forms of variola major develop in approximately 5-10% of infected
people. These forms are almost always fatal; the mortality in the malignant forms is 95%.
-Hemorrhagic smallpox also known as black pox - accompanied by extensive bleeding into the
skin, mucous membranes and gastrointestinal tract
-In the past, serious vaccine complications occurred in approximately 100 per million primary
vaccinations.
Transmission
-Must be continuously transmitted from human to human to survive
-Humans do not become long-term carriers
-Animal reservoirs do not exist
-Spread by direct contact or inhalation of aerosols
-Infectious virus is present in oronasal secretions and in skin scabs
Lecture 6 - Smallpox Feb 10, 2010
1
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