Smallpox

May 2026

 

Smallpox is a disease caused by the variola virus. Smallpox was once a very common and deadly disease. Smallpox was eliminated globally because of successful worldwide vaccination, with the last naturally occurring case in 1977. 

There are concerns that there may be unknown sources of the smallpox virus that may be used for bioterrorist activities. No bioterrorist attack using smallpox has happened in modern times. A single confirmed case of smallpox anywhere in the world would be considered a global health emergency.   

 

Symptoms usually start 10 to 14 days after being exposed but can start anywhere from 7 to 19 days after exposure.

Symptoms include:

  • Fever
  • Headache
  • Back pain
  • Abdominal pain
  • Vomiting
  • Rash or sores which start in the mouth and throat and then spread on the face, arms, legs, hands and feet. The rash usually begins as flat red spots (that can look like pimples), which turn into blisters and then form a crust.

Prior to the elimination of smallpox globally, smallpox was commonly spread from person to person through direct contact with rashes, sores, scabs and fluid from sores and through respiratory droplets that are made while coughing or sneezing. Smallpox can also spread through contact with materials that have been contaminated with the virus such as linen, clothing and bedding.

Someone who has smallpox can spread it to others from the time they develop sores in their mouth or throat until their last scab falls off.

Currently, smallpox vaccines are not recommended for the general Canadian population because the disease has been eliminated and no longer exists in nature.

The Government of Canada maintains several types of vaccines for vaccination against smallpox. If there were a smallpox outbreak, smallpox vaccines would be used to stop the outbreak. If the vaccine is given within four days of exposure to smallpox, it can lessen the severity of the disease or even prevent illness.

Before you visit a doctor or a hospital, call Toronto Public Health immediately.

Toronto residents should call 416-338-7600, Monday to Friday, from 8:30 a.m. to 4:30 p.m., or call 311 after hours and ask to speak to the Communicable Disease Manager. Let health care workers know of your potential exposure to smallpox before seeking health care.

Toronto Public Health will make appropriate arrangements for your medical assessment. Describe your symptoms over the phone, where you have been travelling and mention any possible exposure to smallpox.

If you think you have smallpox, it is important that you isolate immediately:

  • Stay home, separate yourself from those around you in a private room, if possible and do not have physical (skin-to-skin) contact with people, pets or animals.
  • Do not take public transportation, taxi or ride share.
  • Wash or sanitize your hands often.
  • Cover rashes or sores (use bandages, wear a long sleeve shirt and long pants).
  • Ensure that others do not come into contact with your rash, sores or body fluids or anything that may have been contaminated with the virus (e.g., linens, clothing, bedding).

Smallpox is diagnosed through laboratory testing.

There is no specific treatment for smallpox that has been tested in people who are sick with the disease and proven effective. Patients with smallpox can be given supportive care including intravenous fluids, medicine to control fever, and antibiotics for any secondary bacterial infection that can occur.

Several antiviral drugs are currently being tested to treat smallpox. The anti-viral drug tecovirimat (TPoxx®) is a medication authorized by Health Canada for treatment of smallpox under extraordinary conditions.

Call Toronto Public Health at 416-338-7600 (TTY at 416-392-0658) or speak to your health care provider. You can also call 811 to connect to a registered nurse day or night for free, secure and confidential health advice.
Date modified: May 29, 2026