A case of bubonic plague – the disease that killed tens of millions of people in medieval Europe – was reported in rural Oregon last week. The afflicted individual was promptly treated, and health officials believe that there is “little risk to the community” that the disease will spread.
Though the disease, which officials believe was likely passed on to the individual from a sick pet cat, is exceedingly rare in the modern day, a few cases are reported each year. But in 2024, doctors know much better how to treat the disease and prevent its spread.
Here what to know about how an illness once known as the “black death” became treatable:
What is the plague?
The bubonic plague is an infectious disease that can affect mammals, caused by the Yersinia pestis bacteria. It is often transmitted via fleas infected with the bacteria. It can also be caught by inhaling respiratory droplets after close contact with animals or humans sick with pneumonic plague, the most severe form of the disease. Another way it can be caught is “from direct contact with infected tissues or fluids while handling an animal that is sick with or that has died from plague”, according to the Centers for Disease Control and Prevention.
Plague symptoms can manifest in a few ways. Bubonic plague – the kind contracted by the Oregon resident – happens when the plague bacteria get into the lymph nodes. It can cause fever, headache, weakness and painful, swollen lymph nodes. It usually happens from the bite of an infected flea, according to the CDC.
Septicemic plague symptoms happen if the bacteria get into the bloodstream. It can occur initially or after bubonic plague goes untreated. This form of plague causes the same fever, chills and weakness, as well as abdominal pain, shock and sometimes other symptoms like bleeding into the skin and blackened fingers, toes or nose. The CDC says this form comes from flea bites or from handling an infected animal.
Pneumonic plague is the most serious form of the disease, and it occurs when the bacteria get into the lungs. Pneumonic plague adds rapidly developing pneumonia to the list of plague symptoms. It is the only form of plague that can be spread from person to person by the inhalation of infectious droplets.
All forms of plague are treatable with common antibiotics, and people who seek treatment early have a better chance of a full recovery, according to the CDC.
Who is at risk?
In the US, an average of seven cases of human plague are reported each year, according to the CDC, and about 80% of them are the bubonic form of the disease. Most of those cases are reported in the rural western and south-western US.
A welder in central Oregon contracted bubonic plague in 2012 when he pulled a rodent out of his choking cat’s mouth – he survived but lost his fingertips and toes to the disease. A Colorado teen contracted a fatal case while hunting in 2015, and Colorado officials confirmed at least two cases last year – one of them fatal.
Worldwide, most human cases of plague in recent decades have occurred in people living in rural towns and villages in Africa, particularly in Madagascar and the Congo, according to the Cleveland Clinic.
People can reduce the risk of plague by making their homes and outdoor living areas less inviting for rodents, by clearing brush and junk piles, and by keeping pet food inaccessible. Ground squirrels, chipmunks and wood rats can carry plague, as can other rodents, and so people with bird and squirrel feeders may want to consider the risks if they live in an area with a plague outbreak.
The CDC says repellent with Deet can also help protect people from rodent fleas when camping or working outdoors.
Flea-control products can help keep fleas from infecting household pets. If a pet gets sick, it should be taken to a vet as soon as possible, according to the CDC.
Isn’t plague from the middle ages?
The black death in the 14th century was perhaps the most infamous plague epidemic, killing up to half the population as it spread through Europe, the Middle East and northern Africa. It began devastating communities in the Middle East and Europe between 1347 and 1351, and significant outbreaks continued for roughly the next 400 years.
An earlier major plague pandemic, dubbed the Justinian plague, started in Rome around 541 and continued to erupt for the next couple of hundred years.
The third major plague pandemic started in the Yunnan region of China in the mid-1800s and spread along trade routes, arriving in Hong Kong and Bombay about 40 years later. It eventually reached every continent except Antarctica, according to the Cleveland Clinic, and is estimated to have killed roughly 12 million people in China and India alone.
In the late 1800s, an effective treatment with an antiserum was developed. That treatment was later replaced by even more effective antibiotics a few decades later.
Though plague remains a serious illness, antibiotic and supportive therapies are effective for even the most dangerous pneumonic form when patients are treated in time, according to the World Health Organization.
