All About the Smallpox Virus

Caused by variola virus, GENUS Orthopoxvirus

Basic Knowledge

Smallpox is a highly contagious and sometimes life-threatening disease that was seen as a series of marked blisters around the body. The blisters can become to be filled with pus. Then the blisters begin to crust and within 3 to 4 weeks a scab develops and soon falls off. Other members of the GENUS orthopoxvirus that infect humans are: vaccinia virus, monkeypox virus, and the cowpox virus. There are two clinical forms of smallpox that cause smallpox. Variola major and variola minor. Variola major is the most common and most severe type of smallpox and there are four types of Variola major. The most frequent type of variola major that happens in about 90% of cases is called ordinary. The next type of smallpox is a mild type that can occur in vaccinated people and is called modified. The last two types of variola major are rare but very severe and they are called flat and hemorrhagic. The other clinical form of smallpox is less common, less severe, and the death rates are quite low. That type of smallpox is called variola minor. Researchers have shown that cells infected with the variola virus and the monkeypox virus produced a protein that blocks a wide rang of human infecterons, which are molecules produced by our immune systems meant to stop viral replication. So overall, the variola virus causes smallpox by stopping molecules that are meant to stop multiple virus from replicating.

The Transmission of Smallpox

Smallpox can be transmitted through bodily fluids. Not only that but smallpox can be transmitted from direct contact with contacted objects such as clothing or bedding. It is rare, but smallpox can be spread in the air in enclosed buildings such as a building. Humans are the only hosts for the smallpox virus. Smallpox can not be transmitted to animals or insects.

Distribution/Occurence of the Disease

Evidence suggests that smallpox was found on the face of mummies from the 18th-20th Egyptian dynasties. Also, the disease spread along trade routes in Africa, Asia, Europe because people were coming in contact with new things. The disease eventually reached America in the 1500's during the Colombian Exchange. Smallpox was very prominent during the Colombian Exchange (transfer of goods from the Old World to the New World and vice versa). During the Colombian Exchange, smallpox had a great effect on the Native Americans. The Native Americans were not immune to the disease because before the Colombian Exchange they had no contact with the Old World. Native American populations that were greatly affected by smallpox lost all of their population, while other Native American populations usually lost about 90% of their population. Also, smallpox can effect anyone of any age, gender group, or ethnic group. The virus is less effective in tropical countries, where the heat caused it to deteriorate rapidly.


Those who do not get the vaccination for smallpox, about 30% of those people may die. While those who are vaccinated became immune to the disease. The hemorrhagic form of smallpox resulted in death (uniformly), while the flat form of smallpox caused death with most of the cases. Those who do survive go through many complications such as scarred skin, blindness, arthritis, and osteomyelitis.

by: Alyshia Sykes