Smallpox
NOTE TO ALL HEALTHCARE PROFESSIONALS:
If you suspect that a patient is infected with smallpox, immediately call Acute Communicable
Disease Control to assist with diagnosis and implementation of infection control.
(213) 240-7941 (7:30AM-5:00PM, Mon-Fri)
(213) 974-1234 (After Hours, Emergency Operator)
Smallpox is a serious, contagious, and sometimes fatal infectious disease caused by the variola
virus (an orthopoxvirus). There is no specific treatment for smallpox disease, and the only
prevention is vaccination. The smallpox vaccine contains the “live” vaccinia virus—not dead
virus like many other vaccines. The name smallpox is derived from the Latin word for “spotted”
and refers to the raised bumps that appear on the face and body of an infected person.
There are two clinical forms of smallpox. Variola major is the severe and most common form of
smallpox, with a more extensive rash and higher fever. There are four types of variola major
smallpox: ordinary (the most frequent type, accounting for 90% or more of cases); modified
(mild and occurring in previously vaccinated persons); flat; and hemorrhagic (both rare and
very severe). Historically, variola major has an overall fatality rate of about 30%; however,
flat and hemorrhagic smallpox usually are fatal. Variola minor is a less common presentation
of smallpox, and a much less severe disease, with death rates historically of 1% or less.
Smallpox outbreaks have occurred from time to time for thousands of years, but the disease is
now eradicated after a successful worldwide vaccination program. The last case of smallpox in
the United States was in 1949. The last naturally occurring case in the world was in Somalia
in 1977.
Vaccination against smallpox is no longer recommended for the public due to
eradication of natural disease. In the event of reintroduction of smallpox or any kind of
smallpox emergency, vaccination against smallpox will be resumed as appropriate.
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