Plague, caused by bacteria and transmitted through flea bites and infected animals, can develop in three different forms. Bubonic plague causes swollen lymph nodes, while septicemic plague infects the blood and pneumonic plague infects the lungs.
Pneumonic — the kind the Chinese patients have — is more virulent and damaging. Left untreated, it is always fatal, according to the World Health Organization (WHO).
During the Middle Ages, plague outbreaks devastated Europe, killing around 50 million people. Since then, we’ve invented antibiotics, which can treat most infections if they are caught early enough — but the plague isn’t gone. In fact, it’s made a recent comeback.
In the United States, there have been anywhere from a few to a few dozen cases of plague every year, according to the Centers for Disease Control and Prevention. In 2015, two people in Colorado died from the plague, and the year before there were eight reported cases in the state.
Having caused close to 50,000 human cases during the past 20 years, the plague is now categorized by WHO as a re-emerging disease.
How do you get plague? Is it curable?
The bacteria persists because low levels circulate among populations of certain rodents, the CDC says. These infected animals and their fleas serve as long-term reservoirs for the bacteria.
There is currently no effective vaccine against plague, but modern antibiotics can prevent complications and death if given quickly enough. However, a strain of bubonic plague with high-level resistance to the antibiotic streptomycin, which is usually the first-line treatment, was seen recently in Madagascar.
Untreated bubonic plague can turn into pneumonic plague, which causes rapidly developing pneumonia, after bacteria spreads to the lungs.
How do you protect yourself from plague?
Key steps for prevention of plague include eliminating nesting places for rodents around your home, sheds, garages and recreation areas by removing brush, rock piles, trash and excess firewood, according to the CDC.
Report sick or dead animals to law enforcement or your local health officials, do not pick up or touch them yourself. If you absolutely must handle a sick or dead animal, wear gloves.
Use insect repellent that contains DEET to prevent flea bites and treat dogs and cats for fleas regularly. Do not sleep with your pets as this increases your risk of getting plague. Finally, your pets should not hunt or roam rodent habitats, such as prairie dog colonies.
Susan Scutti contributed to this report.