Britannica
Sources used in this answer
Why were hemorrhagic cases of smallpox usually fatal?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
smallpox
Edward Jenner vaccinating his child against smallpox; colored engraving.
Hemorrhagic smallpox, sometimes referred to as black smallpox, was a severe and typically fatal manifestation of the disease.
These cases were characterized by a deep red, hemorrhagic rash that appeared during the initial fever, often before the development of the characteristic focal smallpox eruption. The high fatality rate in these instances was driven by the overwhelming toxic effects caused by the presence of massive quantities of the variola virus in the blood, which triggered a severe inflammatory response from the body’s immune system.1
Patients with this form of the disease frequently succumbed to the infection before the typical, less-toxic stages of the illness could even manifest.1