Smallpox is a contagious and sometimes fatal disease caused by the variola virus. The disease is characterized by fever and a distinctive rash that forms blisters on the skin, which then scab over and fall off.
Symptoms of smallpox usually appear 10-14 days after infection and include:
High fever
Headache
Body aches
Back pain
Vomiting
Rash on the face, arms, and legs that progresses to the trunk
Blisters that fill with clear fluid and then become pus-filled and crusty
Scabs that fall off after about three weeks, leaving scars
Smallpox primarily affects the skin, but it can also affect other organs, such as the lungs, liver, and spleen. The virus is highly contagious and can be spread through contact with an infected person or contaminated objects. The disease was eradicated through a global vaccination campaign led by the World Health Organization (WHO) in 1980, and smallpox no longer exists naturally in the world