Pneumonic plague

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Pneumonic plague, a severe type of lung infection, is one of three main forms of plague, all of which are caused by the bacterium Yersinia pestis. It is more virulent and rare than bubonic plague. The difference between the versions of plague is simply the location of the infection in the body; the bubonic plague is an infection of the lymphatic system, the pneumonic plague is an infection of the respiratory system, and the septicemic plague is an infection in the blood stream.

Typically, pneumonic form is due to a spread from infection of an initial bubonic form. Primary pneumonic plague results from inhalation of fine infective droplets and can be transmitted from human to human without involvement of fleas or animals. Untreated pneumonic plague has a very high fatality rate.

Pathophysiology

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 exclusively 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 Death. It could kill 90%–95% of a population if the victims coughed and passed on the bacteria.

Epidemiology and Demographics

Since 2002, the World Health Organization (WHO) has reported seven plague outbreaks, though some may go unreported because they often happen in remote areas. Between 1998 and 2009, nearly 24,000 cases have been reported, including about 2,000 deaths, in Africa, Asia, the Americas and Eastern Europe. 98 percent of the world's cases occur in Africa.

Natural History

The pneumonia progresses for two to four days and may cause respiratory failure and shock. Patients will die without early treatment, some within 36 hours.

Prognosis

Pneumonic plague is a very aggressive infection requiring early treatment. The mortality rate from untreated pneumonic plague approaches 100%.

Diagnosis

Symptoms

The most apparent symptom of pneumonic plague is coughing, often with hemoptysis (coughing up blood). 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.

Initial pneumonic plague symptoms can often include:

• Fever
• Weakness
• Headache
• Nausea

Rapidly developing pneumonia with:

• Shortness of breath
• Chest pain
• Cough
• Bloody or watery sputum (saliva and discharge from respiratory passages).

Treatment

Medical Therapy

Antibiotics must be given within 24 hours of first symptoms to reduce the risk of death. 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.

Related Chapters

• Bubonic plague
• Septicemic plague

External Links

• Facts about Pneumonic Plague. Centers for Disease Control and Prevention.