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Smallpox
Smallpox (caused by the variola virus) has its origins in cowpox and/or monkey pox
It likely became a human disease ~4,000 years ago
The disease exists in two main clinical forms:
Variola minor, which is relatively mild and had a modern case fatality rate of ~1%
Variola major, which can be quite severe, and had a modern case fatality rate of ~30%
The incubation period lasts 7-17 days, during which the infective is not contagious
The initial period of the disease echos many other illnesses, and the infective may be
contagious
Pustules and, eventually, scabs form; death may result from high fever
The disease is primarily spread by person-to-person respiratory drop transmission; it can also
(more rarely) be spread by objects
Smallpox in History
There is evidence of smallpox-like pustules on the mummy of Ramses V
Historical accounts of smallpox include:
Athens 430BCE
Rome 165CE
China, Japan, and Korea 300–600CE
By 1100–1300CE, smallpox outbreaks had been recorded throughout the Old World
Smallpox epidemics were recorded in the New World in the 1600s
Smallpox reached the South Pacific in the 1800s
Prior to the 19th Century, smallpox caused ~33% of child mortality; ~400,000 deaths per year
The Columbian Exchange
During the 16th–19th Centuries, the Old World disease pool expanded globally through
Overseas exploration, trade, conquest, and colonization
The arrival of Europeans in the New World introduced exotic species
New animals included horses, cows, sheep, pigs, chickens, and rat
New plants included barley, wheat, oats, and a variety of weed plants
Novel bacteria and viruses were introduced to a “naïve” population: smallpox, influenza,
measles, typhus, malaria, diphtheria, whopping cough, plague, and cholera
Many imported species, without natural predators, out-competed and eventually displaced
indigenous species
New insects included the honeybee, and the mosquitos that transmit malaria
Europe got maize, potatoes, coffee, cocoa, chilies, pineapples, squash, pumpkins, peanuts,
cassava, beans, tomatoes, vanilla, avocados, quinine, turkeys…and tobacco, coca leaf, and
syphilis
Virgin Soil Epidemics
“Virgin soil” epidemics occur in populations with no prior experience of a particular infectious
disease
The population consists of 100% susceptibles
e.g. The Yanomami of the Amazon rainforest, Brazil
A 1968 measles epidemic yielded a death rate of 10%, despite modern medical care by
missionaries and nurses
Between 1968 and 2001, the population of one village dropped from ~3,000 to 200 individuals
Disease Epidemics
Why were there such high death rates of Indigenous peoples due to European diseases?
No epidemic disease experience (perhaps resulting in an extreme immune response)
Everyone gets sick at the same time
There is an inability to nurse the sick, fetch water and firewood, and to harvest crops
No quarantine
Immediate Impacts:
50-90% depopulation over a few years
Famine
The loss of elders and leaders
Psychological numbing, despair, and suicide
Long-term impacts:
Loss of traditional beliefs and conversion to Christianity
Increased reliance on European technology
Social and political disruption; civil wars
Abandonment of homelands and the creation of refugees
Smallpox in the New World
Indigenous populations suffered a 40-60% mortality rate when exposed to smallpox
Major epidemics were recorded in:
1521 (Aztec)
1525 (Inca)
1633 (Northeast)
1838 (Plains)
1862 (Coastal B.C.)
Smallpox and the African Slave Trade
Smallpox contributed significantly to the depopulation of the New World, creating a ‘need’ for
new slave labour
From the 16th to 19th Centuries, approximately 11,000,000 Africans were enslaved
10-40% of those captured died on slave ships
Variolation
Involves inoculation with the smallpox virus
The procedure used dried material taken from scabs; this material was blown or inhaled into
the nose
The weakened virus caused a milder form of the infection
Variolation had a mortality rate of ~2%, as opposed to 30% due to natural exposure
Practiced in China ~1100C.E.; introduced to the Americas by African slaves
Lady Mary Wortley Montagu (British royalty) suggested it be tried on prisoners and orphans in
1721
The experiment was successful and was used on the royal family
As a result, the procedure was fashionable from the 1740s – 1780s
Vaccination
Vaccination involved inoculation with the cowpox virus (now vaccinia virus), pioneered by
Edward Jenner
Widespread in Britain by 1796
In the 1800s, it was employed in Europe and the New World
Vaccination had a very low mortality rate: ~1/100,000 to 1/1,000,000
Vaccination and Public Health
Britain – compulsory vaccination
1799 – soldiers
1840 – free for the poor
1853 – all infants
1871, 1874 – all children
Continental Europe
1816 in Scandinavia and Russia
1902 in France
Compulsory vaccination raised ethical questions:
Individual vs. Collective rights
Prevention vs. Destruction
20th Century outbreaks in New York highlight the risk of low vaccination uptake
These concerns apply to vaccines more generally, as recent outbreaks of measles and whooping
cough suggest
Resistance to Vaccination
The reasons for anti-vaccination movements around smallpox:
Vaccinations were painful and caused smallpox
Compulsory vaccinations represent interference by the state
Vaccinations are against God’s will
The middle class saw smallpox as a disease of the poor; the vaccination scar was a sort of
“branding”
Eradication of Smallpox
North America/Europe: 1949
Smallpox Eradication Program commenced in 1966
Most of Africa by 1970
Asia by 1975
The last natural case of smallpox occurred in Somali in 1977
WHO declared smallpox as eradicated on Dec. 9, 1979
Storage of Smallpox
Samples of smallpox are kept in secure labs at the CDC in Atlanta, and at the Vector Institute, in
Koltsovo, Russia
Why store live smallpox?
Because of the risk of bioterrorism
Because of the potential for an accidental outbreak or mutation of the monkeypox virus
For research into safer vaccines