Marmots are large ground squirrels, a kind of rodent that have historically been linked to pests outbreaks in the region.
Tests confirmed that the teenager had bubonic plague and the authorities in Tugrug District, Gobi-Altai Province, had taken quarantine measures.
The quarantine, which started on Sunday, runs until Saturday and the authorities have already isolated 15 people who came into contact with the teenager. All of them are healthy.
Rodents are the main vector of pest transmission from animals to humans, but the disease can also be transmitted through flea bites or from person to person.
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.
From 1928 to 2018, 692 cases of marmot plague were recorded in Mongolia. Of these, 513 died from the disease, which corresponds to a mortality rate of just over 74%.
Earlier this month, two other people in neighboring Khovd province tested positive for bubonic plague, leading to warnings from officials in nearby Russia.
Officials from the Russian Ministry of Agriculture and Food urged citizens in the border area not to hunt marmots or eat marmot meat and to take preventive measures against insect bites.
The Russian embassy in Mongolia quoted Sergei Diorditsu, a representative of the World Health Organization (WHO) in Mongolia, who is said to have seasonal outbreaks of the plague, according to the Russian state media program RIA Novosti.
“There are natural herds of plague in Mongolia and the disease is transmitted by tarbagans (Mongolian marmots),” the embassy said.
“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 China’s Inner Mongolia region confirmed a plague case in the city of Bayannur, northwest of Beijing, on July 7, according to the Xinhua State News Agency.
In 2019, a couple died in Mongolia after eating a raw marmot kidney, which triggered a quarantine that left several tourists stranded in the region.
A squirrel in the US state of Colorado tested positive for the plague last week.
The United States reports up to a few dozen cases each year, according to the Centers for Disease Control. Two people died of the plague in Colorado in 2015.
The plague has recently made a comeback and the World Health Organization has classified it as a recurring disease.
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.