Public health officials have confirmed that they have found fleas in Arizona, the USA that have tested positive for the bubonic plague – the infectious disease responsible for the Black Death in the Middle Ages.

Back in June, three people were treated for plague in New Mexico (400 miles east). The western states in the United States get the majority of plague reports largely because of native rodent species such as ground squirrels and prairie dogs.

A public health warning from the Navajo County Health Department states:

“[We are] urging the public to take precautions to reduce their risk of exposure to this serious disease, which can be present in fleas, rodents, rabbits and predators that feed upon these animals. The disease can be transmitted to humans and other animals by the bite of an infected flea or by direct contact with an infected animal."

Plague is caused by bacteria found in fleas and small mammals. These fleas can be transferred from wild animals to domestic animals, meaning there’s an increased risk of getting plague if you sleep in same bed as a pet.

Although the disease was responsible for 200 million deaths across Europe and Asia in the 14^th Century, the bubonic plague is not purely a disease from the history books. The Centre for Disease Control (CDC) says that the USA has seen around 1,000 cases of human plague in the last 100 years. Between 1,000 and 2,000 cases of plague are reported to the World Health Organisation (WHO) every year.

Bubonic plague is the most common type of plague and affects the lymph nodes. Although the condition can be severe, bubonic plague is very treatable if caught early.

Public Health England (PHE) confirmed last year that there had been no confirmed cases of the plague in the UK since 1918.