The Black Death is back.

One of the most devastating pandemics in human history, the Black Death — also known as the plague — killed more than 25 million people in Europe, Asia, and North Africa at its peak between 1348 and 1350. And it has re-emerged in Madagascar.

Last year, 60 people died there from the bubonic plague — the highest death toll in the world. And last week, 20 people from a single remote village died from it.

Madagascar’s Pasteur Institute, which confirmed that the deaths had occurred due to plague, is worried that the plague may now spread to towns and cities due to unsanitary conditions. Caused by Yersinia pestis bacteria, the bubonic plague is transmitted from rats to humans via fleas. In October, the International Committee of the Red Cross warned that Madagascar, which has been in a state of turmoil since the 2009 coup that brought Andry Rajoelina — a 39-year old former DJ — to power, was at risk of an epidemic.

And the news gets worse: Today, two cases of the deadlier pneumonic plague — which unlike bubonic plague, can be transmitted from human to human — were confirmed.

Those infected with the bubonic plague develop oozing swollen pustules called buboes on their lymph glands and suffer from fever, headache, chills, and weakness as well. Pneumonic plague attacks the lungs, causing breathing difficulties. It can kill in less than 24 hours.

The plague is usually treatable with antibiotics, especially if detected early, but the danger of outbreaks like this is that the plague may mutate into a more contagious and less treatable form. Antibiotic-resistant plague was first spotted in the wild as early as the 1990s, and antibiotic-resistant strains were developed by both the American and Soviet biological warfare programs during the Cold War.

So this is not just Madagascar’s problem: Breeding in the unsanitary conditions on the island are bacteria that pose a threat to people around the world.