This highly infectious disease was once one of the most feared worldwide.
Dr Gill Jenkins last medically reviewed this article in August 2009.
Smallpox
On this page
- What is smallpox?
- Symptoms of smallpox
- Smallpox - causes and risk factors
- Smallpox - treatment and recovery
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What is smallpox?
Smallpox infection is caused by the variola virus and is highly infectious. It's most often spread by inhaling virus particles from an infected person.
The incubation period between infection and the appearance of symptoms is between seven and 17 days.
People don't become infectious until they develop symptoms. They're most infectious during the first two weeks.
Smallpox kills around one in three of those who become infected.
Symptoms of smallpox
The initial symptoms of smallpox are:
- Fever
- Muscle aches
- Headache
- Vomiting
- Tiredness
Over the next one or two days, the distinctive smallpox rash appears all over the body.
The rash develops into vesicles (small, fluid-filled blisters), particularly on the face, arms and legs, but also in the mouth and throat. These crust and fall away after three to four weeks.
Smallpox - causes and risk factors
The last case of smallpox caught in the community was in 1977.
Smallpox was declared eradicated worldwide in 1980 following successful immunisation programmes.
Effective vaccines are available to protect people from smallpox infection. The virus is now thought only to exist in a few stockpiled research laboratory samples.
Smallpox - treatment and recovery
There's no specific treatment for smallpox infection. Treatment is of the specific symptoms and is supportive.
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