The fungus, called Cryptococcus gattii, first made its appearance in British Columbia six years ago where it has killed eight people and infected hundreds more humans and animals since. It is believed to have migrated from the border through Washington's Whatcom County.
Health officer Greg Stern told Associated Press that the fungus is invisible to the naked eye. Other press reports suggest that it can grow on trees, float in the air and even live in water. One can get infected by breathing in the spores although it cannot be passed between humans and animals, nor is it believed to be contagious.
The fungus is sometimes resistant to medication that is used to treat a more common, related fungus, Cryptococcus neoformans, which infects people with weak immune systems.
It can take two to 12 months before any infection is detected, usually in the lungs. Symptoms include shortness of breath, weight loss, fever, headaches, night sweats, and cough and chest pains.
Dr. Eleni Galanis, a physician epidemiologist for the British Columbia Centre for Disease Control, told the Daily Herald the fungus "seems to have spread south" and that at this point, "it's hard to say whether it will go farther."
Since doctors have not been asked to report the infection to the state, there could be many more unreported cases, according to Rebecca Baer, an epidemiologist who tracks the fungus for the Washington State Department of Health.
Not everyone exposed to the fungus will become ill.
