Authorities in the Chinese region of Inner Mongolia are on high alert after a suspected case of bubonic plague, the disease that caused the Black Death pandemic.
The case was discovered in the city of Bayannur, located northwest of Beijing, according to state-run Xinhua news agency. A hospital alerted municipal authorities of the patient's case on Saturday. By Sunday, local authorities had issued a citywide Level 3 warning for plague prevention, the second lowest in a four-level system.
The warning will stay in place until the end of the year, according to Xinhua.
Plague, caused by bacteria and transmitted through flea bites and infected animals, is one of the deadliest bacterial infections in human history. During the Black Death in the Middle Ages, it killed an estimated 50 million people in Europe.
Bubonic plague, which is one of plague's three forms, causes painful, swollen lymph nodes, as well as fever, chills, and coughing.
Bayannur authorities warned the public to report findings of dead or sick marmots -- a type of large ground squirrel that is eaten in some parts of China and the neighboring country Mongolia, and which have historically caused plague outbreaks in the region.
The marmot is believed to have caused the 1911 pneumonic plague epidemic, which killed about 63,000 people in northeast China. It was hunted for its fur, which soared in popularity among international traders.
The advent of antibiotics has helped to contain plague outbreaks, preventing the type of rapid spread witnesses in Europe in the Middle Ages.
But while modern medicine can treat the plague, it has not eliminated it entirely -- and it has made a recent comeback, leading the World Health Organization (WHO) to categorize it as a re-emerging disease.
Anywhere from 1,000 to 2,000 people get the plague every year, according to the WHO.