The latest case of the plague has again been recorded in Inner Mongolia, where the three previous cases have stemmed from. The local was a rural herder in the Siziwang county, who was diagnosed and subsequently treated in hospital. He is now said to be in a stable condition, although four others who came into contact with him have been quarantined.
Health authorities in China confirmed it is a case of the bubonic, rather than pneumonic, plague, which was known as the Black Death in the 14 century.
Bubonic plague sees swelling of the lymph nodes throughout the body. However, pneumonic plague infects the lungs, making the disease airborne and much easier to transfer.
Three other cases of the plague have been confirmed in China this month, with two of them being pneumonic.
Paul Hunter, Professor of Health Protection at the University of East Anglia, told Express.co.uk: “The worrying thing about the Chinese cases is that two are pneumonic plague.
“If you’re bitten by a flea, typically you’ll get bubonic plague where it is in the lymph nodes and they swell and then discharge.
“In pneumonic plague it goes to the lungs and then you start coughing it up.
“And the scary thing about pneumonic plague is that it is substantially more fatal untreated and has a much higher mortality rate.
“You can spread it person to person as you’re coughing, the bacteria then drifts in the air and then people inhale it.
According to the Centre for Disease Control (CDC) in the US, the plague is treatable with antibiotics. The CDC advises the earlier people seek treatment, the more likely it is they will make a full recovery.
Those who come into close contact with plague victims may need preventative antibiotic therapy. In the 21st century, the plague is endemic to select regions of the planet.
Three countries where the plague still circulates are the Democratic Republic of Congo (DRC), Madagascar, and Peru. Isolated cases often also spring up in the US, with up to a dozen people diagnosed annually.