Pneumonic plague is the second most virulent and second least common form of plague (after septicemic plague), caused by the bacterium Yersinia pestis. Typically, pneumonic form is due to a secondary spread from advanced infection of an initial bubonic form. Primary pneumonic plague results from inhalation of aerosolized infective droplets and can be transmitted from human to human without involvement of fleas or animals. Untreated pneumonic plague has a very high case-fatality ratio.
Pathology and transmission
Pneumonic plague can be caused in two ways: primary, which results from the inhalation of aerosolised plague bacteria, or secondary, when septicemic plague spreads into lung tissue from the bloodstream. Pneumonic plague is not vector-borne like bubonic plague; instead it can be spread from person to person. There have been cases of pneumonic plague resulting from the dissection or handling of contaminated animal tissue. This is one type of the formerly known Black Plague. It could kill 90%-100% if they coughed and passed on the bacteria.
Bubobic Plague Symptoms
The most apparent symptom of pneumonic plague is coughing, often with hemoptysis. With pneumonic plague, the first signs of illness are fever, headache, weakness, and rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery sputum. The pneumonia progresses for 2 to 4 days and may cause respiratory failure and shock. Without early treatment, patients will die.
Prognosis and treatment
Pneumonic plague is a very aggressive infection requiring rapid antibiotic treatment within around 24 hours of infection.
Early treatment of pneumonic plague is essential. To reduce the chance of death, antibiotics must be given within 24 hours of first symptoms. Streptomycin, gentamicin, tetracyclines, and chloramphenicol are all effective against pneumonic plague.
Antibiotic treatment for 7 days will protect people who have had direct, close contact with infected patients. Wearing a close-fitting surgical mask also protects against infection.
Without treatment, the mortality rate from pneumonic plague approaches 100%.
Source: www.wikipedia.org 8-3-09
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