People in northwestern Canada and the US are beginning to suffer from a fungus that is usually found in tropical locations.

In four US states, the fungus has made at least 60 people sick, and killed 15.

Cryptococcus gattii, which grows on or around trees, can be treated with anti-fungal medication.

However, it leads to illnesses that take months to show symptoms.

Health officials in North America have asked doctors to look out for symptoms of Cryptococcus gattii infection in their patients.

Julie Harris, an epidemiologist with the US Centers for Disease Control and Prevention (CDC), said that people's risk in the Pacific Northwest was still quite low.

As for the fungus, it began to appear in Canada over a decade ago, and scientists think it spread southward into the US.

However, a different strain of the fungus has also been found in the US, making doctors wonder why the fungus is located there at all.

Over the past several years, health authorities in the state of Oregon have recorded 43 cases, with a further 15 in Washington, and one in California.

Health authorities in Idaho, which is not a coastal state, have also recorded one case.

Symptoms of Cryptococcus gattii exposure include shortness of breath, persistent coughing, and headaches.

Some cases have also caused people to develop symptoms that doctors may confuse with pneumonia or meningitis.

Eleni Galanis, an epidemiologist with the British Columbia Centre for Disease Control in Canada, said that 272 cases of such illnesses had been noted in the province.

She said that, while the death rate sounded high, it was quite possible that many more people had been asymptomatic.

Authorities in the US have also reported more than 50 cases in cats, dogs, ferrets, elk, and porpoises.