WASHINGTON, D.C. – 

The CDC has released a warning for doctors to screen patients with flu-like symptoms for the pneumonic plague, after ISIS has threatened biological warfare.

The disease, caused by a bacterium called Yersinia pestis, most often is transmitted to humans through rodent flea bites or by handling infected animals. Pneumonic plague differs from bubonic plague in its symptoms and the fact that it can be spread through the air rather than just by contact.

Unlike bubonic plague, pneumonic plague can be spread from person to person. According to the CDC, “Pneumonic plague affects the lungs and is transmitted when a person breathes in Y. pestis particles in the air.”

Usually associated with the massive waves of “black death” that swept across Europe during the Middle Ages, the plague still occurs occasionally in the United States, though it is treatable with modern antibiotics.

Although the disease is treatable, terrorists may try to catch people off guard. Pneumonic plague is one of the most pathogenic microbes in the world. Symptoms are sudden and similar to a violent flu, followed by lessions in the groin, armpit, and neck lessons. Eventually the fingers and toes turn black from lack of circulation followed by uncontrollable seizures and death within 36 hours. The CDC advises anyone with these symptoms insist they are tested for pneumonic plague.