Smallpox I. Introduction In 1518, the Aztec Empire included about 30 million people. By 1568, the estimates are that only 3 million people remained in the area covered by the Aztec Empire. What happened? - In 1519, Hernan Cortes landed in Mexico, followed by more Spaniards from Cuba a year later. - An African slave who came in 1520 had smallpox. - Cortes actually first beat up the second group of Spaniards (from Cuba), and then turned inland. - One of his soldiers contracted the disease. - In fighting with the Aztecs, the Spanish eventually had to retreat (glossing over lots of details here), but the infected soldier died. - The Aztecs contracted smallpox from the dead soldier. - It took Cortes some time to return to the Aztec capital. In the meantime a Spanish priest left a description of what happened: "As the Indians did not know the remedy of the disease…they died in heaps, like bedbugs. In many places it happened that everyone in a house died and, as it was impossible to bury the great number of dead, they pulled down the houses over them so that their homes become their tombs." - This left the Aztec army in tatters, and Cortes easily defeated the remmants. - His soldiers said they couldn't walk through the streets without stepping on the bodies of victims. Some years later, the same thing happened to the Inca's. Between 60% and 90% of the population died. In North America smallpox wiped out 90% of the Native American population on the Massachusetts coast (1617-1619). Overall, some estimates say that 90 - 95% of the native population of the New World died due to smallpox. And it's not just the new world: The Plague of Athens in 430 B.C. may have been smallpox (33% mortality rate) The Antonine plague may have been smallpox (killed between 2000 and 5000 people a day in

Rome during it's height. (Incidentally - this seriously weakened the Roman Empire when it most needed men to fight off invaders)). In India, around 400 a plague was described as coming with pustules & boils. In the 18th century smallpox killed about 400,000 people every year (including 5 reigning monarchs) The Franco-Prussian war triggered an outbreak that killed 500,000 people from 1870 - 1875. Smallpox has a 30% mortality rate (in those with some resistance). II. Causes A virus belonging to the poxviridae - a double stranded DNA virus. Closely related viruses cause cow pox, monkeypox & vaccinia III. Spread and infection Spreads through inhaling of the virus. It's highly contagious. This usually comes the mouth, nose or pharynx of an infected person. - Being around someone (face to face) who's infected is a good way to spread smallpox. - Also spreads through contact with bodily fluids or contaminated clothing. It's most contagious 7 - 10 days after rash first appears (more on that soon), but stays contagious until rash disappears. Humans are the only known hosts of smallpox (though monkeys have been infected in a lab setting). After infection, the virus spreads to the mouth and throat areas, and local lymph nodes. Eventually it spreads into the bloodstream. IV. Symptoms There are two clinical forms of smallpox: Variola minor: a rarer manifestation of smallpox. Symptoms are much milder and mortality rate is less than 1%. Variola major: the most severe form of smallpox, most common: Usually symptoms show up 10 to 12 days after infection. Initial symptoms are very similar to the flu (or even the cold):

- fever - muscle pain - malaise - headache - prostration (can't get up) - nausea/vomiting - backache This is followed by more classic symptoms: - lesions appear in mouth, throat, tongue, etc. - fever drops - lesions rupture, releasing large amounts of virus into saliva About two days after this: - skin lesions appear. Usually start on forehead, then spread to face, trunk, etc. fairly quickly (1 - 1 ½ days). Disease then takes one of several different courses: 1) Typical: - lesions become raised “papules”, filled with fluid - this is tissue debris, not