Smallpox Facts: Diseases of the World

Smallpox is an infectious disease that is caused by either Variola major or Variola minor viruses.

Smallpox is an infectious disease that is caused by either Variola major or Variola minor viruses. Scientists believe that smallpox was first transmitted to human beings from a terrestrial African rodent between 16,000 to 68,000 years ago in Egypt. This is before the emergence of agricultural practices in ancient Egypt. This is evident from the mummified body of Pharaoh Ramses which had pustular rashes. The diseases killed large number of people during the last quarter of the 18th century with the most affected age group being children. After the success of the smallpox vaccination, the World Health Organization declared that the infectious disease had been eradicated in 1980. The last case of naturally occurring smallpox was recorded in October 1977.

Sign and Symptoms

After contracting smallpox, a victim may take around 12 to 14 days to manifesting the signs and symptoms. Immediately after inhalation, the Variola major begins to attack the mouth, throat, and the respiratory tubules. The virus then multiplies rapidly as it moves around the body cells. All this happens in the incubation period without any visible sign. The virus then gets into the bloodstream, spleen, and in the bone marrow. The initial symptoms resemble those of other common viral diseases such as influenza and the common cold. The victims experience high fever, muscle pain, prostration, severe headaches, and malaise. As the virus proceeds to affect the digestive system, nausea, vomiting, and frequent loss of appetite are experienced. The most distinct symptom of smallpox is a rash which appears all over the body. The virus attacks the skin cells leading to the formation of rashes. The rashes first appear on the forehead before spreading to the rest of the face, then the entire body. In extreme cases, smallpox has caused blindness and death to the victims.

Mode of Transmission

The smallpox causing virus is mainly transmitted through inhalation. The airborne variola gets into the body through the mouth or the nasal cavity. Transmission occurs through face-to-face contact with an infected person. The virus is highly contagious. It can be transmitted from an infected person who is within a range of 2 meters. Contact with infected body fluids like saliva can also transmit the virus. Infected objects like clothing can transmit the virus as well. The virus is more prone to spreading at the stage when the rash is developing. Generally, the virus causing smallpox spread slowly but widely compared to other viral diseases. In temperate regions, smallpox has been observed to be common during winter and spring. In tropic regions, smallpox has affected people all year round.


The earliest known prevention of smallpox was known as inoculation. Inoculation produced lasting immunity against the virus. In simpler terms, inoculation is the induction of an artificial immunity in the body meant to prevent smallpox infection.

The smallpox vaccine that is modernly used has been a great success. The smallpox vaccine developed by Edward Jenner has gone a long way in the eradication of the disease. Through the vaccination, a live virus is introduced into the body. The vaccine will fight the variola virus after it is introduced in the body. However, in some parts of the world, the vaccine is no longer administered because of the full eradication of the disease.

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