Pneumonic plague is a really serious lung infection, often described as the most virulent form of plague.
There are two other types of plague: bubonic, which affects the lymph nodes; and septicaemic, which affects the blood.
Pneumonic plague can occur after an initial infection of one of these other types.
Symptoms include shortness of breath, chest pain, and often coughing up blood.
It’s regarded as being more serious but less common than bubonic plague.
The global number of infections of all three types of plague varies each year, but it is probably somewhere between 1,000 to 3,000 cases.
Most of these are bubonic plague, and many of them occur in central Africa, but cases also develop in other places, including Russia, India, China, and the United States.
Prof Piero Olliaro is Professor of Poverty-Related Infectious Diseases at the University of Oxford.
He said: “Plague itself has not disappeared: the bacterium that causes it, Yersinia pestis, persists in animal reservoirs across many parts of the world.
“Around 200 rodent species can harbour the bacterium, with reservoirs found across the Americas, Eurasia and Africa.
“Sporadic human cases therefore continue to occur, but established surveillance, infection-control measures and effective antibiotic treatment are important tools for limiting their impact.”
