Bubonic cases are rare, but there are still a few flare-ups of the disease from time to time.
Madagascar saw more than 300 cases during an outbreak in 2017. However, a study in medical journal The Lancet found less than 30 people died.
In May last year, two people in the country of Mongolia died from the plague, which they contracted after eating the raw meat of a marmot - the same type of rodent the second suspected case came into contact with.
However, it's unlikely any cases will lead to an epidemic.
"Unlike in the 14th Century, we now have an understanding of how this disease is transmitted," Dr Shanti Kappagoda, an infectious diseases doctor at Stanford Health Care, told news site Heathline.
"We know how to prevent it. We are also able to treat patients who are infected with effective antibiotics."
