Fungus causing valley fever found in Washington soil

A fungus that can cause a potentially fatal illness called valley fever has been found for the first time in the soil of Washington, officials at Washington State University said Monday.

When the fungus, which is normally found in the semi-arid soils of the Southwest, becomes airborne, it can lead to valley fever. It releases tiny spores that get inhaled and lodged in the lungs of humans and certain animals, especially dogs.

In the most severe form of the illness, the spores escape from the lungs and cycle through the bloodstream, setting up infections that destroy bones, cause skin abscesses and inflame the brain. The federal Centers for Disease Control estimated it kills 160 people annually.

Three unrelated cases – in Benton, Franklin and Walla Walla counties – were diagnosed in Eastern Washington in 2010-11. Soil samples taken recently from the same vicinity tested positive for the fungus, proving it can survive in the area, scientists said.

“Do I think it just showed up and made three people sick? No. I think it has probably been in the soil for some time,” said Dr. Tom Chiller of the CDC in Atlanta, which collaborated with the state in its investigation.

Valley fever is most prevalent in parts of Arizona and the San Joaquin Valley of central California.

Because the three people who got sick in Washington had not traveled there, scientists have become “quite certain … the fungus has moved beyond its normal geographical range,” Chiller said in a news release.

“We know that more people are being exposed,” Chiller said. “While the majority of these people will do just fine, it poses a significant health threat to others.”

Experts say people who work in dusty fields or construction sites are most at risk, as are those with weak immune systems.

Washington State University professor emeritus Jack Rogers, who has studied soil fungi for a half-century, said he was surprised to learn of valley fever’s presence in Washington. He had assumed it was limited to the Southwest and parts of Central America.

“Because valley fever is hard to detect and often misdiagnosed by physicians who are not acquainted with it, it’s important to know where cocci’s range is expanding,” Rogers said, calling valley fever by its scientific name.

Changing weather conditions, population sprawl that disrupts the soil and a possible rodent host moving north in search of habitat could explain its move into Washington, Rogers said.

The three Washington cases included a 12-year-old boy who may have contracted the fungal infection while playing in a dirt canyon near his home; a 15-year-old boy believed to have been infected through skin lacerations when his ATV crashed on a dirt track; and a 58-year-old man who may have gotten sick after inhaling spores while working as a construction excavator.

All three survived, WSU said.

But their illnesses prompted scientists to speculate at the time that the fungus was moving into Eastern Washington. Now, soil samples sent to the CDC have tested positive for the fungus, Chiller said.

“We’re no longer speculating,” Chiller said. “We know.”

In early April, the Washington Department of Health sent advisories to physicians and veterinarians statewide to warn them of the fungus.

“Valley fever is not known to be contagious, and there’s no reason for the public to be alarmed,” state veterinarian Ron Wohrle said.