Class Notes (1,100,000)
CA (630,000)
UTSC (30,000)
HLTB21H3 (200)
Lecture 6

lecture 6


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat
Lecture
6

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Smallpox
Æ
History
- 10 000 BC; first agricultural settlements in NE Africa and spread to India through
Egyptian merchants
- skin lesions on mummies (1570-1085 BC)
- Egyptian pharaoh Ramses V (died 1156 BC) shows to have died of smallpox
- Europe in 5th - 6th century
Æ
effects of smallpox
- Plague of Antonine - decline of Roman Empire @ 108 AD
- fall of Spanish/Portuguese population and Aztec empire
- decline in native population in North America
- biological warfare
-- 1754-1767 French-Indian War -- suggested the deliberate use of smallpox to
diminish the American Indian population
- slave trade spread the disease
Æ
Etiology
- Orthopoxvirus -- family of Poxviridae -- variola virus (also responsible for monkey
pox, cowpox, camelpo, chickenpox, and extremely (mouse pox))
Æ
variola major (more virulent)
- mortality rate is 3% in vaccinated and 30% in unvaccinated
- malignant and hemorrhagic forms develop in ~5-10% of infected people --
almost always fatal, 95% mortality rate in malignant
- hemorrhagic smallpox
Æ
black pox, with extensive bleeding into the skin,
mucous membranes, and gastrointestinal tract
Æ
variola minor
- milder disease - mortality rate is ~1% in unvaccinated persons
- mortality is generally higher when individual is under a year old
- serious vaccine complications occurred in ~100 per million primary vaccinations
Æ
Transmission
- most 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 (close contact)
- infectious virus is present in oronasal secretions and in skin scabs
- potential for long distance aerosol spread is controversial -- under certain
conditions such as in hospitals
- transmission on fomites (e.g. contaminated clothing or bedclothes) is possible for
short periods of time
- virus remains viable for up to two days outside of human host
- average incubation period of 12-14 days
Æ
Clinical manifestation
- acute onset-initial clinical signs: fever, malaise, rigors, vomiting, headache,
backache, occasional delirium
- after 2 - 3 days, skin lesions appear
- lesions are most common on the face and extremities
- ~8 - 14 days after first symptoms -- pustules develop scabs and heal
- severe scarring may occur
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