Plague, one of the deadliest bacterial infections in human history, caused an estimated 50 million deaths in Europe during the Middle Ages when it was known as the Black Death.

While extremely rare, the disease is still around today, with a man in New Mexico dying of plague in March after being hospitalized for the disease and a person in Oregon being diagnosed with bubonic plague in February after likely being infected by their pet cat.

It’s transmitted by fleas that live on rodents. Symptoms usually appear within one to seven days after infection and include painful, swollen lymph nodes, called bubos, in the groin, armpit or neck areas as well as fever, chills and coughing.