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Smallpox Lesion


What is Smallpox and How do People Get it?

Smallpox disease is a serious, highly contagious, and often life-threatening infection marked by a rash of round pox (blisters) on the face, arms, and legs. It is caused by the Variola virus.

The last case of smallpox in the United States was in 1949. The last case in the world was in Somalia in 1977. Worldwide vaccine campaigns have wiped out smallpox everywhere. Since the disease no longer occurs naturally anywhere in the world, smallpox vaccination for the general public was stopped because it was no longer necessary. Today, smallpox virus is kept in two approved laboratories in the USA and Russia.


Historically, people got smallpox by touching or breathing in the smallpox virus. This is called being exposed to smallpox. Not everybody who is exposed to smallpox will get sick. But many will, and as the smallpox viruses multiply inside the body, they can cause serious illness.


Smallpox is not spread by insects or animals. There is no naturally-occurring smallpox. Terrorists could use smallpox virus to hurt people on purpose by releasing the virus in public places. If people start to get sick from smallpox, others can be exposed to the virus through:

  • Breathing in the virus from a cough, sneeze, or saliva (spit) of someone with smallpox
  • Touching skin that has smallpox skin blisters
  • Touching contaminated body fluids or objects such as bedding or clothing
  • Breathing in the virus in a room, bus, or train shared with someone who has smallpox
  • Sharing a razor, tableware, or a toothbrush with someone who has smallpox

What if there is a Smallpox Emergency in San Francisco?

The San Francisco Department of Public Health (SFDPH) has a plan to respond quickly to a smallpox emergency. SFDPH will evaluate the smallpox situation and may recommend ways for people to keep themselves and their family safe. Recommendations may include smallpox vaccine for people who have been exposed and are at risk of illness, and steps to take to minimize the risk of being exposed to smallpox
like staying at home or away from crowds of people. SFDPH will also participate in efforts to provide needed medical support and treatment, and to reduce any ongoing sources of smallpox virus.


How can I keep from Getting Smallpox?

To lower your risk of getting sick if terrorists release smallpox virus on purpose:

  • Stay informed. Listen to the news to learn how the emergency is affecting your community and what actions SFDPH recommends people take.
  • If you were exposed to a suspicious substance or if you were in an area thought to containsmallpox virus, it may help to wash your skin and hair thoroughly with soap and water. It may also help to change and wash your clothing, or if you cannot wash your clothes immediately, to put them in a plastic bag to keep them separate from your other things.
  • Stay away from, and keep your children away from, anyone who might have smallpox.
  • Avoid being in enclosed areas with others who may be sick, such as buses and trains.
  • Do not touch the skin area where someone had a smallpox vaccine placed.
  • Wash your hands regularly and avoid touching your eyes, nose, and mouth.

Is there a Medicine or Vaccine (shot) to Prevent Smallpox disease?

There is no medicine to prevent smallpox. However, the smallpox vaccine (shot) is helpful. Vaccine given within 4-7 days after someone is exposed to smallpox virus will prevent or lessen the disease in most people. Protection against smallpox lasts for about 5 to 10 years. It is not clear whether vaccinations received more than 30 years ago (for example in the early 1970's when smallpox vaccination was routine) would help. Although timely vaccine can prevent smallpox, it can also cause serious side effects in some people. If you have a weakened immune system (from cancer, AIDS, daily steroid use, heart disease, or other drug use that weakens your immune system), if you have eczema or another skin condition, if you are pregnant, or if you are allergic to certain antibiotics (polymixin b or neomycin), the smallpox vaccine can have serious side effects and may not be recommended.


Can I Get a Smallpox Vaccine (shot) Now?

No. The vaccine is not normally available to the general public. If there is a smallpox emergency, vaccine may be released to be given to exposed persons and people at highest risk for exposure including members of the public.


Can I Catch Smallpox from Someone?

Yes. Smallpox is highly contagious (spread from person to person). A person with smallpox is most contagious when the smallpox rash is present, but may also be contagious before the rash appears, when the only sign is fever.


What are the Signs of Smallpox disease?

After exposure to the smallpox virus, it usually takes 7-17 days until illness begins. Smallpox generally begins with fever, headaches, body aches, and weakness on day 1. Then:

  • Day 2-3: small, round pox (blisters) appear and spread on the face, arms, legs, and inside the mouth
  • Day 7: the pox turn into bigger blisters and fill with pus
  • Day 12: the blisters crust over; stomach pain and confusion can also occur
  • Week 3-4: the blisters turn into scabs and fall off, leaving pitted scars on the skin

Long-term effects of smallpox include scars, blindness, and deformed hands and feet.


Call your doctor right away if you are having the signs listed above and think you may have been exposed to smallpox. You may need medical treatment.


Is there Treatment for Smallpox disease?

There is no proven treatment for smallpox once the rash appears, but research is underway to find an effective anti-viral medication. Those who are ill with smallpox may benefit from supportive care in a hospital setting.


How can I Find Information during a Smallpox Emergency?

Check the SFDPH website Local media such as newspapers, TV stations and radio will carry emergency instructions. Emergency radio stations include: KCBS 740 AM and KGO 810 AM.


What can I do Now if I am worried about Smallpox?

  • Read about smallpox at and at the CDC page
  • Go to to learn about steps you can take now to prepare for all disasters.
  • Keep a card in your wallet with a list of your health problems, the names and doses of medicines you take, and any medicines you are allergic to.

Additional Information

  • Information on Smallpox for Health Care Providers
    • Reporting: A suspected or confirmed case of smallpox must be reported within one hour to the SFDPH by calling (415) 554-2830. Click here for reporting information.
    • Documents:
      • "Infectious Disease Emergencies: A Preparedness and Response Guide for San Francisco Clinicians"

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