All it took for flesh-eating bacteria to go from harmless organisms to gruesome infectious pathogens was four mutations and about 35 years. That’s what an international group of researchers announced today in a study that outside experts are calling the largest bacterial genome paper ever published.

A man who recently travelled in western Africa is in critical condition in hospital in Saskatoon, according to provincial health officials.

The nature of the illness was not released, but the man has a high fever, in addition to other symptoms. Officials say a diagnosis has not been confirmed.

Saskatchewan’s deputy medical health officer Dr. Denise Werker said Monday that the patient — who had visited Liberia — was being examined for a suspected case of viral hemorrhagic fever.