Survival, Symptoms and Information
Smallpox is a
serious, contagious, and sometimes fatal infectious disease.
There is no specific treatment for smallpox disease, and the
only prevention is vaccination. The pox part of
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.
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. After the disease
was eliminated from the world, routine vaccination against
smallpox among the general public was stopped because it was
no longer necessary for prevention.
caused by the variola virus that emerged in human populations
thousands of years ago. Except for laboratory stockpiles, the
variola virus has been eliminated. However, in the aftermath
of the events of September and October, 2001, there is
heightened concern that the variola virus might be used as an
agent of bioterrorism. For this reason, the U.S. government is
taking precautions for dealing with a smallpox outbreak.
spreads from contact with infected persons. Generally, direct
and fairly prolonged face-to-face contact is required to
spread smallpox from one person to another. Smallpox also can
be spread through direct contact with infected bodily fluids
or contaminated objects such as bedding or clothing. Rarely,
smallpox has been spread by virus carried in the air in
enclosed settings such as buildings, buses, and trains. Humans
are the only natural hosts of variola. Smallpox is not known
to be transmitted by insects or animals.
A person with
smallpox is sometimes contagious with onset of fever (prodrome
phase), but the person becomes most contagious with the onset
of rash. At this stage the infected person is usually very
sick and not able to move around in the community. The
infected person is contagious until the last smallpox scab
If someone comes in contact with smallpox, how
long does it take to show symptoms?
After exposure, it takes between 7 and 17 days for symptoms of
smallpox to appear (average incubation time is 12 to 14 days).
During this time, the infected person feels fine and is not
contagious. (added Nov 13, 2002)
If smallpox is released in aerosol form, how
long does the virus survive?
The smallpox virus is fragile. In laboratory experiments, 90%
of aerosolized smallpox virus dies within 24 hours; in the
presence of ultraviolet (UV) light, this percentage would be
even greater. If an aerosol release of smallpox occurs, 90% of
virus matter will be inactivated or dissipated in about 24
Is there any treatment for smallpox?
Smallpox can be prevented through use of the smallpox vaccine.
There is no proven treatment for smallpox, but research to
evaluate new antiviral agents is ongoing. Early results from
laboratory studies suggest that the drug cidofovir may fight
against the smallpox virus; currently, studies with animals
are being done to better understand the drug's ability to
treat smallpox disease (the use of cidofovir to treat smallpox
or smallpox reactions should be evaluated and monitored by
experts at NIH and CDC). Patients with smallpox can benefit
from supportive therapy (e.g., intravenous fluids, medicine to
control fever or pain) and antibiotics for any secondary
bacterial infections that may occur.
(updated Dec 2, 2002)
Smallpox Symptoms and Progression
(Duration: 7 to 17 days)
Exposure to the virus is followed by an incubation
period during which people do not have any symptoms and may
feel fine. This incubation period averages about 12 to 14
days but can range from 7 to 17 days. During this time,
people are not contagious.
(Duration: 2 to 4 days)
first symptoms of smallpox include fever, malaise,
head and body aches, and sometimes vomiting. The fever is
usually high, in the range of 101 to 104 degrees Fahrenheit.
At this time, people are usually too sick to carry on their
normal activities. This is called the prodrome
phase and may last for 2 to 4 days.
(Duration: about 4 days)
View enlarged image.
emerges first as small red spots on the tongue and
in the mouth.
develop into sores that break open and spread large amounts
of the virus into the mouth and throat. At this time, the
person becomes most contagious.
Around the time
the sores in the mouth break down, a rash appears on the
skin, starting on the face and spreading to the arms and
legs and then to the hands and feet. Usually the rash
spreads to all parts of the body within 24 hours. As the
rash appears, the fever usually falls and the person may
start to feel better.
By the third
day of the rash, the rash becomes raised bumps.
By the fourth
day, the bumps fill with a thick, opaque fluid and often
have a depression in the center that looks like a
bellybutton. (This is a major distinguishing characteristic
will rise again at this time and remain high until scabs
form over the bumps.
(Duration: about 5 days)
become pustules—sharply raised, usually
round and firm to the touch as if there’s a small round
object under the skin. People often say the bumps feel like
BB pellets embedded in the skin.
Pustules and Scabs
(Duration: about 5 days)
begin to form a crust and then scab.
By the end of
the second week after the rash appears, most of the sores
have scabbed over.
(Duration: about 6 days)
The scabs begin
to fall off, leaving marks on the skin that eventually
become pitted scars. Most scabs will have
fallen off three weeks after the rash appears.
The person is
contagious to others until all of the scabs have fallen off.
fallen off. Person is no longer contagious.
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