بالصور Human plaque

Plague is an
infectious disease caused by bacteria called Yersinia pestis. These
bacteria are found mainly in rodents, particularly rats, and in the
fleas that feed on them. Other animals and humans usually contract the
bacteria from rodent or flea bites.
Historically, plague destroyed
entire civilizations. In the 1300s, the "Black Death," as it was
called, killed approximately one-third (20 to 30 million) of Europe's
population. In the mid-1800s, it killed 12 million people in China.
Today, thanks to better living conditions, antibiotics, and improved
sanitation, current World Health Organization statistics show there
were only 2,118 cases in 2003 worldwide.
Approximately 10 to 20
people in the United States develop plague each year from flea or
rodent bites—primarily from infected prairie dogs—in rural areas of the
southwestern United States. About 1 in 7 of those infected die from the
disease. There has not been a case of person-to-person infection in the
United States since 1924.
Worldwide, there have been small plague outbreaks in Asia, Africa, and South America.
Forms of Plague
Y. pestis can affect people in three different ways: bubonic, septicemic, or pneumonic plague.
Bubonic plague


In
bubonic plague, the most common form, bacteria infect the lymph system
and become inflamed. (The lymph or lymphatic system is a major
component of your body's immune system. The organs within the lymphatic
system are the tonsils, adenoids, spleen, and thymus.)
How do you get it?i
Usually,
you get bubonic plague from the bite of an infected flea or rodent. In
rare cases, Y. pestis bacteria, from a piece of contaminated clothing
or other material used by a person with plague, enter the body through
an opening in the skin.
What are the symptoms?i
Bubonic
plague affects the lymph nodes (another part of the lymph system).
Within 3 to 7 days of exposure to plague bacteria, you will develop
flu-like symptoms such as fever, headache, chills, weakness, and
swollen, tender lymph glands (called buboes—hence the name bubonic).
Is it contagious?i
Bubonic plague is rarely spread from person to person

Septicemic plague

This form of plague occurs when the bacteria multiply in the blood.
How do you get it?i
You
usually get septicemic plague the same way as bubonic plague—through a
flea or rodent bite. You can also get septicemic plague if you had
untreated bubonic or pneumonic plague.
What are the symptoms?i
Symptoms
include fever, chills, weakness, abdominal pain, shock, and bleeding
underneath the skin or other organs. Buboes, however, do not develop.
Is it contagious?i
Septicemic plague is rarely spread from person to person.
Pneumonic plague
This is the most serious form of plague and occurs when Y. pestis bacteria infect the lungs and cause pneumonia.
How do you get it?i
You
get primary pneumonic plague when you inhale plague bacteria from an
infected person or animal. You usually have to be in direct or close
contact with the ill person or animal. You get secondary pneumonic
plague if you have untreated bubonic or septicemic plague that spreads
to your lungs.
What are the symptoms?i
Symptoms
usually develop within 1 to 3 days after you are exposed to airborne
droplets of plague bacteria. Pneumonia begins quickly, with shortness
of breath, chest pain, cough, and sometimes bloody or watery sputum.
Other symptoms include fever, headache, and weakness.
Is it contagious?i
Pneumonic
plague is contagious. If someone has pneumonic plague and coughs,
droplets containing Y. pestis bacteria from their lungs are released
into the air. An uninfected person can then develop pneumonic plague by
breathing in those droplets.
Transmission

Y.
pestis is found in animals throughout the world, most commonly in rats
but occasionally in other wild animals, such as prairie dogs. Most
cases of human plague are caused by bites of infected animals or the
infected fleas that feed on them. In almost all cases, only the
pneumonic form of plague (see Forms of Plague) can be passed from
person to person.
Diagnosis
A health care provider can diagnose plague by doing laboratory tests on blood or sputum, or on fluid from a lymph node.
Treatment

When
plague is suspected and diagnosed early, a health care provider can
prescribe specific antibiotics (generally streptomycin or gentamycin).
Certain other antibiotics are also effective.
Left untreated,
bubonic plague bacteria can quickly multiply in the bloodstream,
causing septicemic plague, or even progress to the lungs, causing
pneumonic plague



Prevention


Antibiotics
Health
experts recommend antibiotics if you have been exposed to wild rodent
fleas during a plague outbreak in animals, or to a possible
plague-infected animal. Because there are so few cases of plague in the
United States, experts do not recommend taking antibiotics unless it's
certain a person has been exposed to plague-infected fleas or animals.
Vaccine
Currently, there is no commercially available vaccine against plague in the United States


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