At least 40 people from nomadic communities in northern Siberia have been hospitalized amid an anthrax outbreak that scientists believe was caused by thawing reindeer carcasses.

Northern Siberia has been hit with a bout of weird weather, including a heatwave that has led to record-high temperatures. In the Yamal tundra, which sits above the Arctic Circle, temperatures soared to 95 degrees Fahrenheit, compared to the average of 77 degrees this time of the year. Scientists have linked the heatwave to climate change.

The warm temperatures caused the region's permafrost — a layer of permanently frozen subsurface soil — to thaw, unleashing the deadly bacteria. Scientists believe the melting unearthed the frozen carcass of a reindeer that died in the last anthrax outbreak in 1968.

The Washington Post reported earlier this week that more than 1,500 reindeer died from anthrax infections in the autonomous Yamalo-Nenets district. Governor Dmitry Kobylkin has declared a state of emergency and evacuated and quarantined the communities most at risk of infection, such as nomadic reindeer herders.

Anna Popova, Russia's chief state sanitary doctor, told CNN that the quarantine may last until September. A mass vaccination of reindeer is also underway.

To combat the outbreak, Russian Defense Minister Sergei Shoigu deployed special biological warfare troops from the Chemical Radioactive and Biological Protection Corps, according to the Siberian Times. The troops have been carrying out lab tests and working to safely dispose of the infected animal carcasses. Kobylkin called the operation "an extremely challenging task."

"I think this perhaps will be the first in the world operation cleaning up a territory of mass deer mortality over such distances in the tundra," he said.

Anthrax, a highly contagious disease, is caused by the bacterium bacillus anthracis, and can be caught through breathing spores, eating infected material, or through contact with broken skin. The most virulent forms of anthrax have also been weaponized, and letters containing anthrax spores were mailed to the offices of several media outlets and two US senators in late 2001, killing five people and infecting 17 others.