Plague is divided into three main types — bubonic, septicemic and pneumonic — depending on which part of your body is involved. Signs and symptoms vary depending on the type of plague.

Bubonic plague

Bubonic plague is the most common variety of the disease. It's named after the swollen lymph nodes (buboes) that typically develop in the first week after you become infected. Buboes may be:

• Situated in the groin, armpit or neck
• About the size of a chicken egg
• Tender and firm to the touch

Other bubonic plague signs and symptoms may include:

• Sudden onset of fever and chills
• Headache
• Fatigue or malaise
• Muscle aches

Septicemic plague

Septicemic plague occurs when plague bacteria multiply in your bloodstream. Signs and symptoms include:

• Fever and chills
• Extreme weakness
• Abdominal pain, diarrhea and vomiting
• Bleeding from your mouth, nose or rectum, or under your skin
• Shock
• Blackening and death of tissue (gangrene) in your extremities, most commonly your fingers, toes and nose

Pneumonic plague

Pneumonic plague affects the lungs. It's the least common variety of plague but the most dangerous, because it can be spread from person to person via cough droplets. Signs and symptoms can begin within a few hours after infection, and may include:

• Cough, with bloody mucus (sputum)
• Difficulty breathing
• Nausea and vomiting
• High fever
• Headache
• Weakness
• Chest pain

Pneumonic plague progresses rapidly and may cause respiratory failure and shock within two days of infection. Pneumonic plague needs to be treated with antibiotics within a day after signs and symptoms first appear, or the infection is likely to be fatal.

The plague bacteria, Yersinia pestis, is transmitted to humans through the bites of fleas that have previously fed on infected animals, such as:

• Rats
• Mice
• Squirrels
• Rabbits
• Prairie dogs
• Chipmunks
• Voles

The bacteria can also enter your body if a break in your skin comes into contact with an infected animal's blood. Domestic cats and dogs can become infected with plague from flea bites or from eating infected rodents.

Pneumonic plague, which affects the lungs, is spread by inhaling infectious droplets coughed into the air by a sick animal or person.

The risk of developing plague is very low. Worldwide, only a few thousand people develop plague each year. However, your plague risk can be increased depending on the area where you live and travel, your job, and your hobbies.

Location

Plague outbreaks are most common in rural and semirural areas that are overcrowded, have poor sanitation and have a high rodent population. The greatest number of human plague infections occur in Africa, especially the African island of Madagascar. Plague has also been transmitted to humans in parts of Asia and South America.

In the United States, plague is rare, but it has been known to occur in several western and southwestern states — primarily New Mexico, Arizona, California and Colorado.

Job

Veterinarians and their assistants have a higher risk of coming into contact with domestic cats and dogs that may have become infected with plague. People who work outdoors in areas where plague-infected animals are common are also at higher risk of getting plague.

Hobbies

Camping, hunting or hiking in areas where plague-infected animals reside can increase your risk of being bitten by an infected flea.

Complications of plague may include:

• Death. Most people who receive prompt antibiotic treatment survive bubonic plague. Untreated plague has a high fatality rate.
• Gangrene. Blood clots in the tiny blood vessels of your fingers and toes can disrupt blood flow and cause that tissue to die. The portions of your fingers and toes that have died may need to be removed (amputated).
• Meningitis. Rarely, plague may cause inflammation of the membranes surrounding your brain and spinal cord (meningitis).