Authorities in the Chinese region of Inner Mongolia have stepped up precautions, 24 hours after a hospital in the area reported a case of bubonic plague.
The health committee in the city of Bayan Nur issued a Level 3 warning, the second-lowest in a four-level system.
The warning forbids the hunting and eating of animals that could carry the plague – which is caused by bacterial infection and can be deadly, asking the public to report any suspected cases of plague or fever with no clear causes, and to report any sick or dead marmots (a large ground squirrel).
The infection was first reported on Saturday, though it's not yet clear how or why the patient, a herdsman, might have contracted the disease.
Known as the "Black Death" in the Middle Ages, the disease is often spread by rodents and can be highly infectious, though can be treated with commonly available antibiotics.
The disease is characterised by swollen lymph nodes, though can be hard to identify in its early stages because its symptoms are flu-like.
Infectious diseases doctor at Stanford Health Care, Dr Shanti Kappagoda, told Healthline it's unlikely a single infection would lead to an epidemic.
"Unlike in the 14th Century, we now have an understanding of how this disease is transmitted," Kappagoda said.
"We know how to prevent it. We are also able to treat patients who are infected with effective antibiotics."
While outbreaks of bubonic plague have become increasingly rare, cases of the disease in China are not uncommon.
In May last year, two people in Mongolia died from the plague after contracting it from eating the raw meat of a marmot.
A World Health Organisation (WHO) official told the BBC that raw marmot meat and kidney was thought to be a folk remedy for good health, despite the animals being a known carrier for the disease.