The fungal illness is still considered rare. But an increasing number of people who have breathed it in have become sick or died. Symptoms include a persistent cough, headache and fever.
The fungus seems to grow on or around trees. Over the last six years, health officials have tracked 43 cases in Oregon, 15 in Washington, one in California and one in Idaho.
The tally was reported Thursday by the Centers for Disease Control and Prevention.