Plague is a bacterial disease of rodents that can be spread to humans and other animals by infected fleas. Plague has three forms:

Bubonic plague (infection of the lymph glands)

Septicemia plague (infection of the blood) and

Pneumonic plague (infection of the lungs).

Pneumonic plague can spread from person to person. Pneumonic plague is the most contagious form because it can spread from person to person in airborne droplets.

Causes

The cause of plague, the Yersinia pestis bacterium, was discovered in 1894 by Alexandre Yersin. Soon after, scientists realized that it is transmitted by the bacteria. Theories abounded. Some physicians believed 'miasmas' of poisonous air floated round, infecting all who inhaled them. Others blamed livestock for carrying the plague. Many simply thought that plague was God's punishment for sin. In fact, the bacteria that cause plague can be transmitted from a host such as a rat to a human through the bite of an animal or insect (such as a flea). These bites transport the disease. The animal or insect that spreads the disease is referred to as a vector. More than 200 different rodents and other species can serve as hosts. Hosts can include domestic cats and dogs, squirrels, chipmunks, marmots, deer mice, rabbits, hares, rock squirrels, camels, and sheep.

Symptoms

The common symptoms of plague are -

Fever

Chills

Headache

Rapidly progressive weakness

Painful swollen regional lymph nodes (buboes)

Low blood pressure

Acute respiratory distress

Problems with blood clotting

Fever

Cough

Shortness of breath

Coughing up blood

Any form of plague can be fatal if not treated. Septicemic and pneumonic plagues are more often fatal than bubonic because they are harder to recognize. Fortunately, these types of plague are less common.

Treatment

Treatment consists of antibiotics such as streptomycin, chloramphenicol, or tetracycline. Note: Oral tetracycline is usually not prescribed for children until after all the permanent teeth have erupted. It can permanently discolor teeth that are still forming. Appropriate antibiotics are more than 90 percent effective at treating plague, if started in time. They are usually given via shot. Other treatment depends on the course of the disease.

Available evidence indicates that early treatment, within 24 hours of onset of symptoms, reduces mortality to less than 15%. Delays in the institution of appropriate therapy significantly increase mortality. The antibiotics of choice are streptomycin, gentamicin, doxycycline, ciprofloxacin, and chloramphenicol.