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What is Smallpox?

Smallpox is a contagious, disfiguring and often deadly disease that has affected humans for thousands of years. Before Smallpox was eradicated, it was a serious infectious disease caused by the variola virus. It was a contagious disease that spread from one person to another.

Samples of the smallpox virus have been kept for research purposes. And advances in synthetic biology have made it possible to create Smallpox from published amino acid sequences. This has led to concerns that Smallpox could someday be used as a biological warfare agent.

No cure or treatment for Smallpox exists. A vaccine can prevent Smallpox, but the risk of the vaccine’s side effects is too high to justify routine vaccination for people at low risk of exposure to the smallpox virus.

Most people with Smallpox recovered, but about 3 out of every 10 people with the disease died. Many smallpox survivors have permanent scars over large areas of their bodies, especially their faces. Some are left blind.

Smallpox was eradicated with the success of vaccination, and no cases of naturally occurring Smallpox have happened since 1977. The last natural outbreak of Smallpox in the United States occurred in 1949.


The history of Smallpox is uncertain. Genetic analyses of viral DNA isolated from a mummified child interred in Lithuania’s church suggest that the variola virus had evolved by at least the 17th century.

However, that the virus was circulating in human populations much earlier, based on the recovery of variola virus DNA from teeth and bones of human remains dated to 600-1050 that was uncovered in the region of modern-day Denmark and Russia.

  • In the 6th century, increased trade with China and Korea introduced Smallpox into Japan.
  • 7thCentury Arab expansion spreads Smallpox into northern Africa, Spain, and Portugal.
  • In the 11th century, the Crusades further spread Smallpox in Europe.
  • 15thCentury Portuguese occupation introduces Smallpox into part of western Africa.
  • 16thCentury European colonization and the African slave trade import smallpox into the Caribbean and Central and South America.
  • 17thCentury European colonization imports Smallpox into North America.
  • 18thCentury Exploration by Great Britain introduces Smallpox into Australia.


The first symptoms of Smallpox usually appear 10 to 14 days after you’re infected. During the incubation period of 7 to 17 days, you look and feel healthy and can’t infect others.

Following the incubation period, a sudden onset of flu-like signs and symptoms occurs. These include:

  • Fever
  • Overall discomfort
  • Headache
  • Severe fatigue
  • Severe back pain
  • Vomiting, possibly

A few days later, flat, red spots appear first on your face, hands and forearms, and later on your trunk.

Many of these lesions turn into small blisters filled with clear fluid within a day or two, which then turn into pus. Scabs begin to form eight to nine days later and eventually fall off, leaving deep, pitted scars.

Types of Smallpox

There were two common forms of Smallpox, such as:

What is Smallpox

1. Variola minor: It was a less fatal type of Smallpox. The Centers for Disease Control and Prevention (CDC) estimate that only 1percent of those infected died. However, it was less common than variola major.

2. Variola major: It was more harmful than variola minor. There are also four types of variola major infection presentations.

  • Ordinary variola major: The most common form, The CDC estimates that 90 percent of smallpox cases were variola major. This type of Smallpox killed 30 percent of those infected and 3% of vaccinated individuals. The cause of death is usually bronchopneumonia.
  • The milder or variola major: Accounts for 2% of cases in unvaccinated persons and 25% in previously vaccinated persons.
  • Hemorrhagic variola major: A rare form of variola major which is always fatal and involves hemorrhages in the mucous membranes and the skin.
  • Flat variola major: Another rare form of variola major that is almost always fatal.


By the following way, Smallpox is caused by infection with the variola virus.

  • Directly from person to person:Direct transmission of the virus requires fairly prolonged face-to-face contact. The virus can be transmitted through the air by droplets that escape when an infected person coughs, sneezes or talks.
  • Indirectly from an infected person: In rare instances, the airborne virus can spread farther, possibly through the ventilation system, infecting people in other rooms or on other floors.
  • Via contaminated items:Smallpox can also spread through contact with contaminated clothing and bedding, although the risk of infection from these sources is less common.
  • As a terrorist weapon, potentially: A deliberate release of Smallpox is a remote threat. However, because any virus release could spread the disease quickly, government officials have taken numerous precautions to protect against this possibility, such as stockpiling smallpox vaccine.


People who had Smallpox would be kept in isolation to control the spread of the virus that can prevent the severity of the disease.


1. The smallpox vaccine can prevent Smallpox, also called the vaccinia virus vaccine. The vaccine is made from a virus called vaccinia, a poxvirus similar to Smallpox, but less harmful. There are two licensed smallpox vaccines in the United States and one investigational vaccine used in a smallpox emergency.

Smallpox vaccines can protect people from getting sick, such as:

  • Before contact with the virus, the vaccine can protect you from getting sick.
  • Within 3 days of being exposed to the virus, the vaccine might protect you from getting the disease.
  • Within 4 to 7 days of being exposed to the virus, the vaccine likely gives you some protection from the disease.

2. In July 2018, the FDA approved Tecovirimat (TPOXX) for the treatment of Smallpox. Tecovirimat has not been tested in sick people with Smallpox, but it has been given to healthy people.

Test results in healthy people showed that it is safe and causes only minor side effects. Tecovirimat could also be used under an investigational new drug (IND) protocol to treat vaccinia vaccination’s adverse reactions.

3. In laboratory tests,cidofovir and brincidofovir have also been to stop the virus’s growth that causes Smallpox. Cidofovir and brincidofovir have not been tested in sick people with Smallpox, but they have been tested in healthy people and those with other viral illnesses. These drugs continue to be evaluated for effectiveness and toxicity.


  • Most people who get Smallpox survive. However, a few rare varieties of Smallpox are always fatal. These more-severe forms most commonly affect pregnant women and people with impaired immune systems.
  • People who recover from Smallpox have severe scars, especially on the face, arms and legs. In some cases, Smallpox may cause blindness.
  • Complications of Smallpox arise most commonly in the respiratory system and range from simple bronchitis to fatal pneumonia. Respiratory complications tend to develop on about the eighth day of the illness and can be either viral or bacterial in origin.
  • Secondary bacterial infection of the skin is a relatively uncommon complication of Smallpox. When this occurs, the fever usually remains elevated.
  • Pustules are leading to complications such as conjunctivitis, iritis, corneal ulcer, and optic atrophy.
  • Blindness results in approximately 35 to 40 percent of eyes affected with keratitis and corneal ulcer.

WHO Response

The WHO Smallpox Secretariat, based in WHO’s Headquarters, manages the Smallpox Vaccine Emergency Stockpile, which is maintained in the unlikely event that the virus re-emerges.

The Secretariat also coordinates research activities, manages biosecurity inspections of the repositories, and reports to WHO’s Governing Bodies.

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