•1300 England and Germany suffered epidemics.
•In 16th century it was established in all of Europe except for Russia.
•The English settlers, who arrived in the American colonies in 1617, set
off an epidemic making room for other settlers who came from
Plymouth in 1620.
•In the war of 1763, between England and France for the control of
North America, the British intentionally gave blankets contaminated
with scabs from smallpox to the Indians, and led the tribes to move far
•Smallpox was first introduced into South Africa, by a ship docked in
Capetown in 1713, which carried contaminated bed linen from a ship
returning from India. Smallpox was reintroduced once from a ship
from Srilanka in 1755, and again from Denmark 1767.
•First outbreak in the Americas was among African slaves on the island
of Hisponiola in 1518.
The Disease of Smallpox
•Caused of smallpox is a large virus, which can be seen with the light
microscope. But detailed structure requires an electron microscope.
The outer surface called capsid resembles a diamond and its inner
dumbbell-shaped core contains a double-stranded DNA.
•It has about 200 genes, 35 believed to be involved in virulence.
•Other poxviruses that can infect humans are: monkeypox, cowpox,
milker’s node, tanapox, and chicken pox.
•Enters body via droplet infection by inhalation. Can also be acquired
via direct contact or through contaminated fomites such as clothing.
•The infectious material from the pustules can remain infectious for
•The virus multiplies in the mucous membranes of the mouth and nose.
•During first week of infection there is no sign of illness, but it can still
•Virus moves on to the lymph nodes and then to the internal organs via
the blood stream and multiples again.
•The virus reenters the bloodstream, and around the ninth day the first
symptoms appear: headache, fever, convulsions–quite ill.
•A few days later rash appears.
•Richard Preston in The Demon in the Freezer describes smallpox.
•The individual is infectious a day before the rash appears and until all
the scabs have fallen off.
•Many die a few days or week after the appearance.