Marmots are large ground squirrels, a kind of rodent that have historically been linked to pests outbreaks in the region.
Republican Ministry of Agriculture and Food officials urged citizens in the border area not to hunt marmots or eat marmot meat and to take preventive measures against insect bites.
Rodents are the main vector of pest transmission from animals to humans, but the disease can also be transmitted through flea bites.
The plague has killed an estimated 50 million people in Europe during the Black Death pandemic in the Middle Ages, but modern antibiotics can prevent complications and death if administered quickly enough.
The bubonic plague, one of the three forms of the plague, causes painful, swollen lymph nodes as well as fever, chills and cough.
Mongolia quarantined its region near the Russian border last week after laboratory tests showed two cases of bubonic plague related to eating marmot meat, the country̵
The National Center for Zoonotic Diseases of Mongolia announced last week that it had identified and tested 146 people who had come in contact with the two infected people.
The center also identified 504 people with secondary contact in the Khovd province.
The Russian embassy in Mongolia said “there is no cause for serious concern” as the Mongolian authorities have imposed travel restrictions and isolated people, according to RIA Novosti, the Russian state-run news agency.
The embassy also quoted Sergei Diorditsu, a representative of the World Health Organization (WHO) in Mongolia, who is said to have seasonal outbreaks in the province, according to RIA Novosti.
“There are natural plague sources in Mongolia, and the disease is transmitted through tarbagans [Mongolian marmots]”said the embassy.
“The problem is that, despite all the bans and recommendations from local authorities, residents continue to hunt and eat them as this is a local delicacy.”
Authorities in the Inner Mongolia region of China have also confirmed a case of the plague.
The case in the city of Bayannur, northwest of Beijing, was confirmed on Tuesday, according to the state-run Xinhua news agency.
In 2019, a couple died in Mongolia after eating a raw marmot, which triggered a quarantine that left several tourists stranded in the region.
According to the WHO, 1,000 to 2,000 people contract the plague each year, but this estimate does not take into account unreported cases.
CNN’s Jessie Yeung contributed to this report.