When a Livermore retiree’s cough turned to pneumonia in late 2013, a standard course of antibiotics didn’t help.

The retiree was fit for his age, but he soon became so weak he couldn’t get out of a chair.

His wife took him to an emergency room, where X- rays showed worsening pneumonia. Medical tests failed to reveal the cause of his illness, so doctors gave him a more massive dose of antibiotics. These didn’t help either.

The doctors put him in intensive care on a respirator, but he continued to decline. They told his wife to prepare for the worst.

At the last minute, the results of a sophisticated test from UC-Davis arrived, showing what simpler tests had failed to do: the Livermore man had Valley Fever, a fungal disease endemic to California and the entire southwest.

Quickly treated with one of the standard anti-fungal medications, fluconazole, he began to improve.

Today, the retiree, who asked not to be named in order to protect his family’s privacy, is on his feet, easily tired but no longer in imminent danger. He stopped taking fluconazole for a time, but returned to it when his condition worsened. He continues to take it today and puts up with side effects like hair loss.

His experience illustrates the challenge of dealing with what has been called a “silent epidemic” -- Valley Fever, an illness that is difficult to diagnose for which there is no cure and which cannot be prevented except by not breathing dust, a nearly impossible challenge. Valley Fever is caused by inhaling tiny spores of a fungus called coccidioides that lodge in the lung.

Valley Fever has been known since the late 1800s, but remains a medical puzzle. Research scientists at the University of California at Merced, the University of Arizona and elsewhere are working to understand the body’s response to the spores, so far without consistent success.

Sometimes the inhaled spores remain localized and seem not to trouble the body. Sometimes they generate a respiratory illness that lasts a few weeks. Other times, the body develops a chronic response like painful joints, skin lesions and fluid in the lungs. In the most severe cases, they spread to other organs like the brain and skeleton, and a life or death struggle begins.

“Some people breathe in mouthfuls of the fungus and it doesn’t affect them at all,” said Erin Gaab, a psychologist from UC-Merced who works with Valley Fever patients and their families.

“Others inhale one breath and can develop the serious form of the disease that turns into meningitis.”

Gaab and UC-Merced immunologist Katrina Hoyer spoke last week at a meeting of the Valley Study Group in Pleasanton.

Hoyer is examining the details of immune system response in disease victims. Numbers of patients are small, in part because medical diagnoses are imperfect. Her basic question relates to whether the presence or absence of particular immune cells might correlate with success or failure. So far, no clear pattern has emerged.

The standard literature about Valley Fever, including advice from the California Department of Public Health, suggests that 60 percent of those who are exposed have no symptoms at all. Most of the rest, the literature says, get cold or flu symptoms that go away in a few weeks.

The implication seems to be that there is little to worry about, but reality is far more ominous, according to a Washington State couple that founded a website, called Valley Fever Survivor. The website aims at promoting much greater understanding of the dangers of Valley Fever.

Sharon and David Filip point out that people get over colds and flu, but Valley Fever never truly goes away. It may go dormant, but it is a “ticking time bomb” that can come back years later, perhaps when people are older and have weakened immune systems.

Sharon Filip herself contracted a near-fatal case of Valley Fever after taking her son to the University of Arizona in 2001. “I had heard about the rattlesnakes, about scorpions, about monsoon weather, but nowhere was there a word about Valley Fever,” she said in an interview last week.

David Filip believes that downplaying the seriousness of the disease is intentional. Organizations ranging from local governments to university administrations don’t want to frighten people away.

The Filips are not alone in their complaint about minimizing the danger. That was also the theme put forth by UC-Berkeley professor John Taylor earlier this month at a hearing in Tracy to consider whether the California Parks Department could expand motorized off-road recreation into a new site on the Alameda-San Joaquin County border.

The site is located in a hotspot for Valley Fever, Taylor noted. More cases of the disease can be anticipated when visitors breathe in more dirt thrown up by more spinning tires. He cited a $12 million legal judgment rendered against CalTrans in Kern County after contract workers came down with Valley Fever, and warned that the state Parks Department will face the same liability if it opens the new park.

Valley Fever is a disease of the Americas, with rare diagnoses in Europe and Asia after travelers arrive from the western hemisphere. The Filips say they know a woman who got Valley Fever in Germany after importing shipped cactus from Arizona, apparently from inhaling spores on the plant or in its potting soil.

There are an estimated 150,000 new cases of Valley Fever per year in the U.S., 25,000 of which show medical symptoms. California’s Central Valley is a hotspot, but most U.S. cases occur in Arizona.

Medical authorities stress that the disease cannot be transmitted from person to person the way, say, a cold can be. On the other hand, people can carry the coccidioides spores in their hair and on their clothing, possible routes to infection in others.

Animals get Valley Fever as well: dogs, cats, cattle, sheep – even snakes and bats, according to information from the University of Arizona.

The disease can be caught at any time of year, although incidence increases from June through November in California. The assumption is that the rainy season encourages strands of the fungus to grow underground, after which they dry up and break apart into spore clusters that can become airborne during the warmer weather that will follow.

In her remarks to the Valley Study Group, Merced immunologist Katrina Hoyer repeatedly stressed how little is understood about Valley Fever or the fungus that causes it.

The fungal variety found in California, called coccidioides immitis, is different from the variety found everywhere else, she said. “Nobody really understands the differences” although it is clear that the disease that the two varieties cause is the same.

Wherever the fungus is found, wind storms can spread its spores much farther. Medical literature refers to 1977 hurricane force winds in the Bakersfield area that caused a fourfold increase in Valley Fever cases, with a surge in incidence as far north as Sacramento.

A sharp increase in California cases also occurred from 1991 through 1994 after a rainy winter ended a 5-year period of drought. The warm, dry summers that followed are thought to have dried fungal spores to be carried aloft by strong winds.

Valley Fever seems to be spreading with a changing climate. “There have been a lot of cases identified in Washington State recently” through animal research, Hoyer said.