Symptoms and Signs of Smallpox

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/11/2019

Doctor's Notes on Smallpox

Smallpox (also called variola) is a viral illness caused by a poxvirus transmitted from person to person that causes high fever and characteristic rash. About one-third of those infected may die. Due to the success of an intense global public health initiative, smallpox is the only disease that has been completely eradicated worldwide, but it remains a potentially devastating biological weapon.

Symptoms of smallpox infection can take one week to 17 days to appear and may include fever, chills, vomiting, body aches, headache, felling unwell (malaise), muscle aches, backache, and confusion. About 48-72 hours after the initial smallpox symptoms, a characteristic rash appears and turns into virus-filled sores, which later scab over. These sores may easily be mistaken for chickenpox. Just after the rash appears, the virus is highly contagious. When the scabs heal and fall off a depression or light-skinned scar remains.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.