Smallpox Facts: From Prevention to Treatment

By: Michael Lam, MD, MPH

Smallpox Facts

Smallpox facts causes a rash and fever Smallpox is caused by the Orthopox virus, variola. This acute viral disease is unique to humans. Smallpox facts show that it has a high case fatality rate and is highly contagious. There is at least 2 strain, variola major and the variola minor.

  • Variola major: the more severe form with case fatality rate up to 30-50% in susceptible population.
  • Variola minor: milder form of the disease with more diminutive pox lesions, case fatality rate of 1-2% in susceptible population.

Although this disease has been eradicated, there are concerns that virus is being exploited as a biological weapon.

Incubation period

7 – 19 days (average 12 days)

Clinical Features

  • Acute onset of fever, malaise, rigors, vomiting, headache and backache. 15% of patients developed delirium. Erythematous rash may be seen in some patients. Exanthem appears 2-3 days into the disease progression together with discrete rash on the face, hands and forearms.
  • Rash spread centrally to the trunk. Skin lesions quickly progressed from macules to papules and eventually to pustular vesicles. Lesions are more abundant on the face and extremities. This centrifugal distribution is an important diagnostic feature. In distinct contrast with chickenpox, lesions on various segments of the body remain generally synchronous in their stages of development.
  • From 8-14 days after onset, the pustule scabs that leave depressed depigmented scar upon healing.
  • Smallpox virus can be readily recovered from scabs throughout convalescence. Therefore, patients should be isolated and considered infectious until all scabs separate.
  • Two rare forms of smallpox have been reported.
    1. Pupura variolosa or hemorrhagic type small pox: 3% of persons with variola major would develop purpura variolosa. Dark, purplish, blotchy flushing of skin appeared at the initial stage of the disease. Patients suffered from severe loss of blood into skin and internal organs and died before the typical smallpox rash would appear.
    2. Flat type smallpox: occurs in 5% of people with variola major. Skin lesions of these patients developed more slowly, never raised above the surface of the skin.

Key Differential Diagnosis

Chickenpox, monkeypox, disseminated herpes zoster.

Laboratory Investigations

  • Electron microscopy, PCR, viral isolation (culture of pharyngeal swab or lesions).
  • Guarnieri bodies on Giemsa or modified silver stain.


  • Supportive care.
  • Antibiotics may be used for secondary bacterial infection.
  • Any combined case of smallpox is an international emergency with immediate report made to public health authorities.


  • Vaccination after exposure to a case of smallpox may prevent or ameliorate disease, however supplies of smallpox vaccine are scarce worldwide.

Isolation Precautions

  • Isolate patients preferably in negative pressure isolation room.
  • Patients should be considered infectious until all scabs separate and should quarantine during this period.
  • Droplet and airborne precaution for a minimum of 17 days following exposure for all persons in direct contact with the index case.

Case Fatality


How Do Viruses Relate to AFS and Our Health?

Smallpox facts and the virusOur immune response to viruses and AFS takes place via the NeuroEndoMetabolic (NEM) system. The NEM is a complex web made up of all the organs and organ systems in our body.

One piece of this entire system is the inflammatory response to things such as AFS or smallpox. Our response to perceived threats – like toxins, damaged cells, or pathogens – involves the integration of the immune cells, the gut, and the microbiome. One of the body’s first lines of defense and responses to stress or threats is through inflammation. Inflammation is utilized as a way of eradicating the initial cell injury source, to cleanse the body of tissues and cells that were damaged from the threat, and to rebuild tissues. In this way, inflammation is tied to the way our body detoxifies itself. Chronic low-grade inflammation from this previously mentioned cell process has also been linked to depression.

Smallpox Facts – How the Body Perceives Viruses and Stress

The body perceives viruses and stress in the same way, which causes our bodies to show an array of undesirable symptoms – which can include the presence of AFS. Distinguishing them can be difficult, so it is important to understand smallpox facts. Together, six types of stress responses from the NEM – including inflammation and detoxification – work to fight stress and restore homeostasis. The body creates a worsening cascade, so dysregulation of this system can result in great harm to our health. Healing and reversal of AFS is crucial to our well-being and our body’s ability to protect itself. AFS – like a virus – causes a severe reaction that if not treated, can result in extreme damage to our bodies and even death.

If we can promote a healthy immune system, we can in turn ensure proper stress response and detoxification. Reversal of AFS is a way to secure this wellness goal.

Smallpox facts