Smallpox Overview

Organism that causes the disease:
  • The organism that causes the disease is the Variola virus. There are two types of the virus; Variola major and Variola minor. Variola major is much more deadly than Variola minor.

Variola virus causes smallpox.

Primary Host:

  • The only host for smallpox is the human. It is transmitted human to human.

Mode of transmission:
  • Smallpox is easily transmittable from person to person. It can be spread through saliva droplets or through bed sheets and clothing, because the virus can survive in these environments for long periods of time. The smallpox virus can stay alive in favorable conditions for up to 24 hours. However, in unfavorable conditions it can survive for only up to 6 hours. Favorable conditions are without sunlight. It is a highly contagious disease that is the most contagious for the first week of symptoms, or until the scabs from the rash fall off.

Organ system affected:
  • The Integumentary Sysytem is the only system affected by smallpox.

Major Symptoms: smalpox.jpg
  • Skin rash
  • Backache
  • Delirium
  • Diarrhea
  • Excessive bleeding
  • Fatigue
  • High fever
  • Malaise
  • Severe headache
  • Vomiting

The main symptom of smallpox is a rash
covering the skin.

Incubation period:
  • The incubation period for smallpox is 12 days. After the 12 day incubation period a rash or the symptoms of smallpox begins to appear. However, over the next 2-3 weeks the rash will consistently worsen and go through different stages.The stages are:
    1. Mascules are tiny, flat red spots that usually first appear in the throat and mouth. They can easily go unnoticed until a rash on the skin appears. Rashes on the skin are most concentrated on the face, feet and hands.
    2. Papules are red spots that turn bumpy. They usually grow to about 0.1 in. in diameter.
    3. Vasicles are lesions that are filled with fluid. Usually, they are about 0.2 in. in diameter.
    4. Pustules are lesions that have become firm, dome-shaped, whitish, and pus-filled. They begin to grow larger with depressed centers. The rash enters this stage usually about 4-7 days after the rash first appears. The bumps remain in this stage from days 5-8.
    5. Crusts are pustules that turn into scabs. These scabs appear about two weeks after the rash appears. The scabs usually fall off 3-4 weeks after the origin of the rash.
  • The following video discusses the incubation period of smallpox the symptoms. It then goes on to explain how smallpox ends:

Mortality rate:
  • In Colonial times smallpox was a major illness where the death rate was 30-35% for people infected with the Variola major virus. The other form of smallpox which is much less deadly is the Variola minor virus which only has a 1% death rate.

Treatment... Colonial vs Modern:

  • MODERN: Smallpox was officially eradicated in 1979. However, until 1979 if you were exposed to smallpox or believed to have it, it was recommended that one get the smallpox vaccine 1-4 days after being exposed because it can lessen the severity of the disease or prevent the disease all together. Along with immediately getting the vaccine, smallpox victims were recommended to be isolated and closely monitored. After the disease was diagnosed there were few treatment options because no drug kills the virus that causes the disease. However, some antibiotics may have shortened the duration of the disease.
  • COLONIAL: During the smallpox epidemic in Colonial times the only form of treatment was variolation. The townspeople set up facilities where people with the disease could go for inoculation through variolation. Variolation consisted of making a small cut in the arm of a healthy person and then applying scabs from a person with smallpox to the cut. John Adams, who spent time in the variolation facility at Castle William in Boston Harbor, writes of his experience to Abigail Adams saying, "They [the doctors] took their Launcetts and with their Points divided the skin for about a Quarter of an Inch and just suffering the Blood to appear, buried a Thread about (half) a Quarter of an Inch long in the Channell. A little Lint was then laid over the scratch and a Piece of a Ragg pressed on, and then a Bandage bound over all." Variolation was safer than getting the disease the natural way. However, variolation disappeared in 1796 when English physician Edward Jenner discovered that the germs from cowpox worked as immunity for smallpox. Based off this discovery vaccinations were created. People also drank large amounts of water that had been in contact with tar for two days.
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John Adams was in a Variolation facility at Castle William in Boston where he was innoculated against smallpox.


Read more at Suite101: Smallpox and Variolation in Colonial Boston: Epidemic in 1764 Brought John Adams to Boston for Inoculation

Possible Complicactions:
  • Arthritis and Bone infections
  • Brain Swelling
  • Eye Infections or Blindness
  • Pneumonia
  • Scarring (especially on the arms and legs)
  • Severe Bleeding
  • Skin infections
  • Death

Demographic affected:
  • In the Colonial times the Native Americans were the main group to get smallpox because they were less resistant to the disease. The pilgrims and travelers from the Old World had a resistance to smallpox because they had developed an immunity to it through generations of exposure.


Native Americans were the main group affected.