The Centers for Disease Control and Prevention issued an update this week instructing doctors to consider the possibility of plague when they see patients complaining of flu-like symptoms.

Plague, the ancient disease most often associated with the Black Death during the Middle Ages, is not extinct.

A few cases usually pop up each year in the United States, but this year has been especially bad. Since April, 11 cases have been detected and three people have died.

"It is unclear why the number of cases in 2015 is higher than usual," said the CDC update.
States where human plague has been diagnosed are Arizona (two), California (one), Colorado (four), Georgia (one), New Mexico (two), and Oregon (one).

According to the Centers for Disease Control, plague is caused by the bacteria Yersinia pestis, carried by fleas and rodents.

Bubonic plaque is the most common type of plague, but is not contagious.

Plague is characterized by fever, chills, headache, muscle aches, and swelling of the lymph nodes that appear two to seven days after infection.

The CDC says healthcare providers should consider plague in patients who report flu-like symptoms if they reside or have traveled in the western U.S., and if they've been exposed to rodent habitats or have been in direct contact with rodents or ill domestic animals.

According to the CDC, the mortality rate for untreated plague has ranged as high as 93 percent, but antibiotics reduce mortality to about 16 percent. The quicker the patient is treated, the better the outcome.

The CDC offers the following tips for avoiding plague:

• If plague is in your area, wear long pants when possible and use insect repellent on clothing and skin.

• Never feed squirrels, chipmunks, or other rodents, and avoid contact with ill or dead animals.

• Use flea control products on pets

• Reduce rodent habitat by removing brush, clutter, and food sources around your home.