Health officials in Colorado are investigating a suspected human case of the plague, the rare bacterial infection that killed tens of millions of people in Europe in the 14th century. Today, it is easily treated with antibiotics.
The U.S. Centers for Disease Control and Prevention estimates that there are about seven cases of plague in humans each year in the U.S. In February, officials in Oregon reported that a person had likely contracted the disease from a sick cat.
Surprised to hear the plague is still around? Here’s what you need to know.
What is the plague?
Bubonic plague is the most common form of this bacterial infection, which spreads naturally among rodents such as prairie dogs and rats.
There are two other forms of plague: septicemic plague (which spreads throughout the body) and pneumonic plague (which infects the lungs).
Bubonic plague causes painful swollen lymph nodes most commonly found in the groin, armpit and neck, called buboes. It will often progress and turn into the other two forms of plague if left untreated.
According to the Cleveland Clinic, other symptoms of the plague include sudden high fever and chills, headache, and pain in the abdomen, legs and arms.
How can you get the plague?
The bacteria is transmitted through the bites of infected fleas, which then transmit the bacteria to rodents, pets and humans.
People can also get plague from touching infected bodily fluids, so health experts advise extra caution when handling dead or sick animals. Plague can also spread through respiratory droplets from a person with pneumonic plague.
According to Lisa Morici, a microbiologist and immunologist at Tulane University School of Medicine, pneumonic plague is the deadliest and most easily spread. If left untreated, the mortality rate is nearly 100 percent.
Where does the plague occur?
According to the CDC, most cases in the U.S. are occurring in rural areas of northern New Mexico, northern Arizona, southern Colorado, California, southern Oregon and far western Nevada.
According to the World Health Organization, plague is most endemic worldwide in the Democratic Republic of Congo, Madagascar and Peru.
How do you treat the plague?
The plague has never been eradicated, but we have become better at preventing its spread and treating the disease in people.
If the plague is treated early with antibiotics, it can be cured. The most important thing is to see a doctor quickly — otherwise the plague can be fatal.
And as the old saying goes, prevention is better than cure.
Keeping your home free of debris and other things that can attract rodents can help reduce your risk of infection. You can also make sure your pets are up-to-date on flea treatments. When hunting, camping, or otherwise spending time outdoors, the CDC recommends using a bug spray containing DEET to keep fleas and other disease-spreading pests at bay.
Is there a vaccine?
Yes, but the World Health Organization recommends it only for people at high risk of infection, such as laboratory and healthcare workers. There is no vaccine for plague available in the U.S.
Morici said more research is needed. The vaccines used in other parts of the world work against bubonic plague, but there is no strong evidence that they also protect against pneumonic plague.
She said it would be ethically and logistically difficult to develop a trial of a vaccine against the plague.
“Because bubonic plague is very treatable with antibiotics and is also quite rare – you don’t see thousands and thousands of cases of plague every year – there just isn’t a big market for a plague vaccine right now,” Morici said.