A formerly tropical fungus is behind at least 15 deaths in the U.S. Pacific Northwest over six years, health officials say.

The fungus, called Cryptococcus gattii, is considered rare. The U.S. Centers for Disease Control and Prevention described cases of infection in the U.S. since 2004 in its weekly report on death and disease, published online on Friday.

Patients' symptoms included:

• Cough, 56 per cent.
• Shortness of breath, 51 per cent.
• Headache, 53 per cent.
• Fever, 42 per cent.
• Weight loss, 40 per cent.
• Neck stiffness, 21 per cent.

The British Columbia Centre for Disease Control (BCCDC) has also recorded 272 cases since 1999, including 191 among people on Vancouver Island. The illness can affect the lungs and nervous system of humans, according to the BCCDC website.

Of the 60 reported U.S. cases of C. gattii since 2004, 43 were in Oregon, 15 in Washington and one each in California and Idaho, according to the report.

Of the 15 fatalities, nine of the patients who were tracked after becoming infected died because of their infection, and six died with the infection although that was not the primary cause of death. In two of the nine fatalities due to C. gattii there was no predisposing medical condition, the CDC said.

More awareness needed

The deaths all occurred in the Pacific Northwest: 12 in Oregon and three in Washington.

"Physicians should consider C. gattii as a possible etiology [cause] of infection when treating patients (particularly those who are HIV negative) who have signs and symptoms of cryptococcal infection, and should ask patients about recent travel to the Pacific Northwest, British Columbia, or other C. gattii-endemic areas," the report says.

The CDC is also aware of 52 cases of infection among animals. The agency called for more awareness of the infection among public health practitioners, physicians, and veterinarians.

There are no firm figures on cause of death among people infected in B.C. since those who catch the fungus may be sick for a long time and death can occur months or years later.

But in April, researchers reported the mortality rate for recent C. gattii cases in the Pacific Northwest was running at about 25 per cent or six deaths out of 21 known cases analyzed in the U.S., compared with a mortality rate of 8.7 per cent or 19 out of 218 known cases in British Columbia at that time.

The infection can be treated with antifungal medication, but there is no vaccine to prevent it nor any precautions to take to avoid it. With files from The Associated Press, The Canadian Press