FRESNO — The soaring nationwide figures for valley fever don't tell the whole story.

Problems with screening for the disease and tracking it over time mean thousands of cases go undetected and untreated every year, leading experts to believe the second epidemic likely is worse than documented.

Valley fever often goes unrecognized, especially in places where the disease is not widespread. Doctors aren't familiar with its symptoms; often, they are similar to those of pneumonia.

Health experts say more awareness by the public and the medical community could reveal many more cases and associated costs.

"With valley fever, you have to think of it to diagnose it," said Kings County health officer Dr. Michael Mac Lean. "It is underdiagnosed throughout California, and that problem is worse the less endemic your county is."

During the early 1990s outbreak that generated interest in the disease, the cases reported in Kern County probably represented only about 10 percent of the total, according to a 1996 article published in the journal Emerging Infectious Disease. That study and others lead experts to believe that while there were 13,000 cases of the disease diagnosed and reported nationwide in 2011, it is likely that more than 130,000 went undiagnosed.

Given the wrong care

Patients suffering from valley fever endure unnecessary surgeries and medical treatment, while the disease goes untreated. They are often prescribed antibiotics, which have no impact on the fungus. This is an especially big problem in states that don't typically see cases of the disease.

"When snowbirds leave from Minnesota to spend the winter in Arizona or California, they may come down with this illness, and their doctor back in Minnesota may think its bacterial pneumonia," said Dr. Benjamin Park, who leads fungal disease research at the Centers for Disease Control and Prevention. "Some people get misdiagnosed with cancer, and it turns out they have cocci. The delay in a correct diagnosis can mean patients having unnecessary procedures, receiving unnecessary medications and also suffering from the lack of peace of mind that comes with knowing what is wrong."

Patients well-informed enough to ask doctors about the disease fare better. An Arizona Department of Health Services study, which included 493 patients, found those who had knowledge of the disease were twice as likely to request testing from their doctors. But there is little funding or support for public awareness campaigns at the state or federal level.

The California Department of Public Health, for example, would issue a public announcement when someone was diagnosed with West Nile Virus this year and another when a patient died, part of an annual pattern of regular updates on the virus. It also issued two warnings last month on hantavirus after six visitors to Yosemite National Park acquired it. There is no similar campaign for valley fever, even as the number of cases has grown more than 12-fold from 1990 to 2011, to 6,146 cases statewide.

Testing rates and reporting differ within the Central Valley, a valley fever hot spot. In Kern County, there were 2,780 cases diagnosed in 2011, compared with 785 in nearby Fresno, and 125 in San Joaquin. More cases were found in Orange County, 124, than in Merced, which reported 73.

The high rates of cases in communities where valley fever is considered to be highly concentrated, where physicians are most likely to order the diagnostic test, underscore the underreporting elsewhere.

In the Kings County community of Avenal, physicians are so accustomed to seeing valley fever, they are likely to order a blood test on a patient's first visit, Mac Lean said. "Probably if you get valley fever in Avenal, you are more likely to go and get evaluated, and more likely to get diagnosed," he said.

The extent of underdiagnosis becomes clear when reviewing cases reported by state and federal prisons in the valley.

In August, a former prisoner of the Taft Correctional Institution near Bakersfield won a $425,000 settlement from the U.S. government after suing the federal Bureau of Prisons, accusing it of permanently damaging his health because he got valley fever in prison.

"This prison was, in essence, a petri dish for valley fever, into which the BOP inserted human beings without their consent," the lawsuit said.

Because these prisons are in dusty areas rife with the cocci fungus and because prison authorities truck in thousands of people with little prior exposure to cocci, the state prison system provides clinicians with extensive education on valley fever, said Nancy Kincaid, director of communications in the Office of the Receiver for California Correctional Health Care Services.