"They protect us, we protect them."

Can anthrax and smallpox appear again with the permafrost thawing?

Freezing is well known to help food preservation by inhibiting microbial growth. Can the dead animals or humans buried in the permafrost as a result of an infectious disease, cause a new epidemic during the thaw which is happening now as a result of global warming? We ask the question.

It was recently shown that permafrost thawing of a several decades reindeer carcass caused the contamination of 1500 reindeer and the hospitalization of 13 members of the Nenets community. Can the same phenomenon happen with the smallpox virus?

Anthrax : the facts

The carcass of a reindeer dead of anthrax and buried several decades ago in the Siberian permafrost has thawed recently with the unusually high temperatures on the region. The consequences have been significant since nearly 2,000 reindeers have died after contracting anthrax while 24 members of the Nenets community were hospitalized (one child died), suffering from the same disease.


Anthrax is caused by a bacterium, Bacillus anthracis, a gram-positive bacillus which spore can resist to drying, heat (100 ° C for several minutes), cold , acids, bases ...). Under favorable conditions, the spore can germinate to give a new pathogen bacteria. It was possible, for example, to germinate spores contained in old Egyptian mummies of more than 3000 years!
In the nineteenth century, it was impossible to put animals on the fields where animals (cattle in particular) have died of anthrax and buried as they were. The new animals died systematically of the same disease: the fields were called " damned fields ". We solved the problem by treating the carcasses with quicklime.
The explanation lies in the fact that the anthrax bacteria became spores in the bodies of the animals. Then, these spores were brought to the surface by worms before being ingested by healthy animals, which then died of anthrax.
Regarding the example of the reindeer just mentioned, the spores contained in the carcass resisted without problems in cold and germinated with permafrost thawing before contaminate other reindeer and humans decades after the death and the burial of the animal.

Smallpox: the facts

In these circumstances, can we fear that the smallpox that killed 40% of the population of a Russian village of East Siberia in the 1890s could contaminate the present population because of the emerging bodies from the thawed permafrost?


Smallpox is transmitted by a virus and not a bacterium. In addition, this virus has a structure known as "enveloped" which gives it a certain fragility (it cannot live a few months in the open air). Moreover, the scientists who examined the corpses have not recovered virus but only DNA sequences.
In the same order of idea, it was not possible to get live virus from the bodies of soldiers who died of influenza in 1918 and locked in the permafrost (but it is true that the influenza virus is particularly fragile).


There is apparently no need to be concerned that smallpox reappear following the thawing of permafrost. However vigilance is necessary. About anthrax, it is absolutely normal to see the disease again, especially because animal vaccinations were abandoned in these regions with the disappearance of the disease.







Nov. 2017
Paris-Nord Villepinte


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