Frequently Asked Questions (FAQ) About Plague
What is plague?
Plague is a disease caused by Yersinia pestis (Y.
pestis), a bacterium found in rodents and their fleas in many
areas around the world.
Why
are we concerned about pneumonic plague as a bioweapon?
Yersinia
pestis used in an aerosol attack could cause cases of the pneumonic
form of plague. One to six days after becoming infected with the bacteria,
people would develop pneumonic plague. Once people have the disease,
the bacteria can spread to others who have close contact with them.
Because of the delay between being exposed to the bacteria and becoming
sick, people could travel over a large area before becoming contagious
and possibly infecting others. Controlling the disease would then
be more difficult. A bioweapon carrying Y. pestis is possible
because the bacterium occurs in nature and could be isolated and grown
in quantity in a laboratory. Even so, manufacturing an effective weapon
using Y. pestis would require advanced knowledge and technology.
Is
pneumonic plague different from bubonic plague?
Yes. Both are caused by Yersinia pestis, but they are transmitted
differently and their symptoms differ. Pneumonic plague can be transmitted
from person to person; bubonic plague cannot. Pneumonic plague affects
the lungs and is transmitted when a person breathes in Y. pestis
particles in the air. Bubonic plague is transmitted through the bite
of an infected flea or exposure to infected material through a break
in the skin. Symptoms include swollen, tender lymph glands called
buboes. Buboes are not present in pneumonic plague. If bubonic plague
is not treated, however, the bacteria can spread through the bloodstream
and infect the lungs, causing a secondary case of pneumonic plague.
What
are the signs and symptoms of pneumonic plague?
Patients
usually have fever, weakness, and rapidly developing pneumonia with
shortness of breath, chest pain, cough, and sometimes bloody or watery
sputum. Nausea, vomiting, and abdominal pain may also occur. Without
early treatment, pneumonic plague usually leads to respiratory failure,
shock, and rapid death.
How
do people become infected with pneumonic plague?
Pneumonic plague occurs when Yersinia pestis infects the
lungs. Transmission can take place if someone breathes in Y. pestis
particles, which could happen in an aerosol release during a bioterrorism
attack. Pneumonic plague is also transmitted by breathing in Y.
pestis suspended in respiratory droplets from a person (or animal)
with pneumonic plague. Respiratory droplets are spread most readily
by coughing or sneezing. Becoming infected in this way usually requires
direct and close (within 6 feet) contact with the ill person or animal.
Pneumonic plague may also occur if a person with bubonic or septicemic
plague is untreated and the bacteria spread to the lungs.
Does
plague occur naturally?
Yes.
The World Health Organization reports 1,000 to 3,000 cases of plague
worldwide every year. An average of 5 to 15 cases occur each year
in the western United States. These cases are usually scattered and
occur in rural to semi-rural areas. Most cases are of the bubonic
form of the disease. Naturally occurring pneumonic plague is uncommon,
although small outbreaks do occur. Both types of plague are readily
controlled by standard public health response measures.
Can
a person exposed to pneumonic plague avoid becoming sick?
Yes.
People who have had close contact with an infected person can greatly
reduce the chance of becoming sick if they begin treatment within
7 days of their exposure. Treatment consists of taking antibiotics
for at least 7 days.
How
quickly would someone get sick if exposed to plague bacteria through
the air?
Someone
exposed to Yersinia pestis through the air—either from
an intentional aerosol release or from close and direct exposure to
someone with plague pneumonia—would become ill within 1 to 6
days.
Can
pneumonic plague be treated?
Yes.
To prevent a high risk of death, antibiotics should be given within
24 hours of the first symptoms. Several types of antibiotics are effective
for curing the disease and for preventing it. Available oral medications
are a tetracycline (such as doxycycline) or a fluoroquinolone (such
as ciprofloxacin). For injection or intravenous use, streptomycin
or gentamicin antibiotics are used. Early in the response to a bioterrorism
attack, these drugs would be tested to determine which is most effective
against the particular weapon that was used.
Would
enough medication be available in the event of a bioterrorism attack
involving pneumonic plague?
National
and state public health officials have large supplies of drugs needed
in the event of a bioterrorism attack. These supplies can be sent
anywhere in the United States within 12 hours.
What
should someone do if they suspect they or others have been exposed
to plague?
Get
immediate medical attention: To prevent illness, a person who has
been exposed to pneumonic plague must receive antibiotic treatment
without delay. If an exposed person becomes ill, antibiotics must
be administered within 24 hours of their first symptoms to reduce
the risk of death. Notify authorities: Immediately notify local or
state health departments so they can begin to investigate and control
the problem right away. If bioterrorism is suspected, the health departments
will notify the CDC, FBI, and other appropriate authorities.
How can the general public reduce the risk of getting pneumonic plague from another person or giving it to someone else?
If possible, avoid close contact with other people. People having direct and close contact with someone with pneumonic plague should wear tightly fitting disposable surgical masks. If surgical masks are not available, even makeshift face coverings made of layers of cloth may be helpful in an emergency. People who have been exposed to a contagious person can be protected from developing plague by receiving prompt antibiotic treatment.
How
is plague diagnosed?
The
first step is evaluation by a health worker. If the health worker
suspects pneumonic plague, samples of the patient’s blood, sputum,
or lymph node aspirate are sent to a laboratory for testing. Once
the laboratory receives the sample, preliminary results can be ready
in less than two hours. Confirmation will take longer, usually 24
to 48 hours.
How
long can plague bacteria exist in the environment?
Yersinia
pestis is easily destroyed by sunlight and drying. Even so, when released
into air, the bacterium will survive for up to one hour, depending
on conditions.
Is
a vaccine available to prevent pneumonic plague?
Currently,
no plague vaccine is available in the United States. Research is in
progress, but we are not likely to have vaccines for several years
or more.
- Page last updated April 5, 2005
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