In severe cases, tissue death can cause skin and extremities to turn black.
While the plague is ultimately a shocking disease, given its history, it is treatable.
According to the Centre for Disease Control (CDC) in the US, the plague is treatable with antibiotics.
The CDC advises the earlier people seek treatment, the more likely it is they will make a full recovery.
Those who come into close contact with plague victims may need preventative antibiotic therapy.