A farmer has become the fourth person to be diagnosed with the plague in Northern China this month.
The unidentified person and four family members have been quarantined, the Ulanqab government in the country’s Inner Mongolia region said on Wednesday.
They have not revealed how the victim caught bubonic plague, otherwise known as the ‘Black Death’, but the illness is generally spread from fleas carried by rats.
Three other people who live 250 miles (400km) away in the Xilingol League province were diagnosed earlier this month.
One man was treated for the bubonic plague after he ate a wild rabbit, while the first two patients were diagnosed with the more fatal and contagious pneumonic strain.
Health officials have urged the public to stay away from wild animals and said workers had tried to exterminate rats and fleas over a 200-acre area around where the patient lives.
Four patients have been diagnosed with the plague in Mongolia. Three were in Xilingol League, while the fourth was in the region Ulanqab
The plague is caused by Yersinia pestis, a bacteria which can be spread by fleas on small animals like rats, rabbits, mice and squirrels.
If the flea bites a human, it can transmit the plague. There is also a risk from eating infected animals or coming into contact with a patient.
The plague then attacks the immune system, causing glands in the armpits and groin to become swollen and painful, and triggers a fever and gangrene.
Although the highly-contagious plague is rare in China, several cases have proven deadly in the past few years.
The pneumonic strain can prove fatal in 24 to 72 hours and is the ‘most virulent form’ of the disease according to the World Health Organisation (WHO). It infects the lungs, making the disease airborne and much easier to transfer.
The bubonic form is less dangerous. However, it is famous for causing the Black Death which killed around a third of all European people in the Medieval era.
The Ulanqab government said the herder from the Suzi River Bank of the Siziwantg Banner, sought medical help at the Siziwangqi People’s Hospital.
It was not disclosed how the patient caught the plague, but officials said they had been ‘active’ in a plague-affected location prior to falling ill.
A statement said the patient has been isolated and treated at the local hospital, and their condition is stable.
Four close contacts have been isolated for medical observation, but at present, there are no abnormalities such as fever.
Anti-flea and rat prevention was carried out around the area of the victim’s house.
The first two cases of the plague to be confirmed were on November 12. Two patients from Xilingol League were diagnosed with pneumonic plague in Beijing.
The third, a 55-year-old from Xilingol League, was also infected with bubonic plague in early November but was confirmed by Chinese health authorities on November 16. He is not believed to be connected to the first two patients.
Experts urged the public to maintain good personal hygiene and wear a mask any time you go to a healthcare setting.
Those with symptoms of a fever, cough, lymph node pain or bleeding have been told to stay away from others but seek a doctor.
Field workers have been advised to strengthen personal protection because they are close to wild animals.
According to China’s National Health Commission, a total of five people have died from the plague between 2014 and September of this year.
In 2014, a man died of the plague in northwestern Gansu province and sparked the quarantine of 151 people.
The 30,000 people living in Yumen, the town where the man died, were also prevented from leaving, with police at roadblocks placed on the town perimeter.
In neighbouring Mongolia, a couple died of the bubonic plague in May after they ate raw marmot meat, another carrier of the plague germ.
Most cases of the plague, only a few thousand globally every year, are in Africa, India and Peru. The US has about seven cases a year, according to the CDC, mostly in rural or remote areas in Southwestern states like Arizona, Colorado, New Mexico, and California.