Russian authorities have confirmed that two people have died after an outbreak of anthrax in Siberia.
Unusually warm weather is believed to be behind the release of the bacteria, which has resulted in the death of a boy and his grandmother.
Another 90 people have been hospitalised on suspicion of infection and more than 2,300 reindeer have perished.
The defence ministry said it had sent more than 200 specialist troops to the region to decontaminate the infected area and burn the corpses of infected animals.
It stressed that there was "no epidemic" and the affected area had been sealed off.
Anthrax is caused by the spores of the bacterium Bacillus anthracis.
It is a deadly infection that has previously been used in biological weapons and in terrorist attacks in the US in 2001, when letters containing anthrax were posted to media offices and US senators.
It is naturally found in soil and occasionally infects livestock while grazing.
It is believed that the current outbreak came from the carcass of a reindeer that died in an anthrax outbreak 75 years ago and has been frozen ever since.
Anthrax can lie dormant in frozen soil such as permafrost for decades and only becomes a problem if the permafrost melts.
Once a grazing animal ingests the bacteria, it quickly starts reproducing in the animal's blood.
It quickly kills, then uses the decomposing animal to spread. Once oxygen enters the rotting animal, the bacteria transforms into spores.
George Stewart, a medical bacteriologist at the College of Veterinary Medicine at the University of Missouri, explained to Live Science that spores are basically a bacterial cell in a really tough protein shell. He said they're in a state of suspended animation and they stay that way in the soil until another grazer accidentally ingests them.
Over the past month, temperatures in Siberia have soared up to 35C. This has melted the upper layers of the permafrost and sparked wildfires. This heat is part of a global trend.
June 2016 marked the 14th consecutive month of record-breaking heat. Globally, it was the hottest June ever recorded, and every one of the 13 months preceding it was also a record-breaker.
The regions around the Poles are experiencing the fastest warming due to global climate changes.
This is causing an inevitable melt of the permafrost and there are fears that other pathogens might also lurk in the frozen soils of Siberia.
In 2015, researchers discovered that a 30,000-year-old virus isolated from permafrost was still infectious, although fortunately it isn’t harmful to humans.
As the world continues to warm, other diseases may be uncovered, and these could be more of a threat.
Additional reporting by Steff Gaulter
Source: Al Jazeera and agencies