Canada has confirmed that a patient who had just recently returned from China was the first person to die from the H5N1 bird flu virus in North America.
The authorities have said it was urgently contacting airline passengers on the victim's flights.
It was also the first known instance of someone in North America contracting the illness, Canada Health Minister Rona Ambrose told a press conference, stressing it was an "isolated case".
Officials said the victim, who had recently returned from a trip to Beijing and had been otherwise completely healthy, was from the province of Alberta.
They added that the person's gender and other identifying details were being withheld to protect the family's privacy.
"I am here to confirm North America's first human case of H5N1, also known as avian flu," Ms Ambrose said, confirming the patient died on 3 January.
"I want to reassure the public this is an isolated case and the risk of H5N1 to Canadians is very low. There is no evidence of sustained human-to-human transmission."
The virus is contracted directly from birds, mainly poultry. The illness it causes in humans is severe and 60% of human cases are fatal.
The victim began to feel ill during the 27 December flight home to Alberta province, developing a fever and headache.
The person was admitted to hospital on 1 January when the symptoms worsened suddenly and they began falling in and out of conciousness.
The patient died two days later.
The federal microbiology laboratory in Winnipeg, Manitoba, identified the H5N1 virus overnight from a specimen that had been taken while the victim was still alive.
Doctors said the victim had travelled with two companions who are not sick but will be kept under observation as a precaution for ten days, double the usual time it takes for the virus to manifest itself.