Smallpox Signs and Symptoms

After infection, symptoms may take from 7-17 days to appear for major types of smallpox. The virus begins growing in the bloodstream 72-96 hours after infection, but no obvious symptoms appear immediately.

• People who have contracted smallpox initially develop such symptoms as fever, body aches, headache, chills, and, particularly, backache. Over half of people with smallpox experience chills and vomiting. About 15% become confused.
  
  
• A rash appears 48-72 hours after the initial symptoms and turns into virus-filled sores, which later scab over. The process can take up to 2 weeks.
  
  
• Just after the rash appears, the virus is highly contagious as it moves into the mucous membranes. The body sheds the cells, and virus particles are released, coughed, or sneezed into the environment. The infected person can be infectious for up to 3 weeks (until the scabs fall off the rash). Live virus can be present in the scabs. After the scabs or crusts fall off (in 2-4 weeks), a depression or light-skinned scar remains.
  
  
• Early in the course of the disease, the rash and pus-filled sores can easily be mistaken for chickenpox. Lesions occur first in the mouth and spread to the face, then to the forearms and hands, and finally to the lower limbs and trunk. In contrast, rash from chickenpox progresses from the arms and legs to the trunk and rarely forms in the armpits, palms, soles, and elbow areas.