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 that thousands of cases go undetected and untreated every year, leading experts to believe the second epidemic is likely worse than documented.

Valley fever often goes unrecognized, especially in places where the disease is not widespread. Doctors aren’t familiar with its wide variety of symptoms. Often the early symptoms of valley fever are similar to those of pneumonia.

Health experts say more awareness by the public and by the medical community could reveal much higher numbers of cases and associated costs.

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

Even during the early 1990s outbreak that first generated interest in the disease, the number of cases reported in Kern County, which is one of the worst hit in California, probably only represented about 10 percent of the total number, according to a 1996 article published in the journal Emerging Infectious Disease.

That study and others lead experts to believe that while 13,000 cases of the disease were diagnosed and reported nationwide in 2011, it is likely that more than 130,000 went undiagnosed.

Patients suffering from valley fever endure unnecessary surgeries and courses of medical treatment while the disease goes untreated. They are often prescribed courses of 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 snow birds 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.

“Some people get misdiagnosed with cancer, and it turns out they have cocci [valley fever fungus]. 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 fare better who are well-informed enough to ask their doctors about the disease. An Arizona Department of Health Services study, which included 493 patients, found that patients who had prior knowledge of the disease were twice as likely to request testing from their doctor. But there is very little funding or support for public awareness campaigns at the state or federal level.

The California Department of Public Health, for example, issued 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 about hantavirus after six visitors to Yosemite National Park acquired it. There is no similar campaign for valley fever, even as the number of cases grew by more than twelvefold between 1990 and 2011 to 6,146 cases statewide.

Awareness of the disease among the medical community plays a role in misdiagnosis and underreporting, too. Testing rates and reporting differ even in areas of the Central Valley, which is known to be a valley fever hot spot. In Kern County there were 2,780 cases diagnosed in 2011, compared with 785 in nearby Fresno County and 125 in San Joaquin County. More cases were found in Orange County — 124 — than in Merced County, which reported 73.

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

In the Kings County community of Avenal, physicians are so accustomed to seeing valley fever cases that they are now likely to order a blood test on a patient’s first visit, MacLean 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 the state and federal prisons located in the Central 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 (BOP) and accusing it of permanently damaging his health because he acquired 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 located in dusty areas known to be 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.

Many prisoners also are susceptible to becoming severely ill from cocci because they already have weaker immune systems from drug use and other diseases, such as AIDS and hepatitis. So anytime an inmate has a symptom that falls inside the constellation of valley fever symptoms, prison clinicians perform a blood test, Kincaid said. When they test, they find valley fever at very high rates.

In 2005, researchers found that the rate of valley fever in Pleasant Valley State Prison was nearly 40 times the rate found in residents of Coalinga and 600 times the rate in Fresno County. Were that same level of testing applied to the broader population in the Southwest, more than 350 new cases would be found every day, research indicates.

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