Doctors in the San Joaquin Valley have a new, fast way to help diagnose Valley fever using a test developed in a Fresno hospital laboratory.
The new DNA test for the fungal disease -- a first in the state -- can provide results in five hours instead of the two-plus weeks it now takes for a blood or culture test.
The sooner patients with Valley fever can be diagnosed and receive treatment, the better, doctors say. The disease can spread from the lungs, causing meningitis and other problems -- and can be fatal. There is no cure, but drugs can prevent the infection from growing.
Until now, a doctor who suspects a patient has Valley fever would order a blood test. If there's a positive antibody reaction, a sample would be sent to the University of California at Davis laboratory for a confirmation test. A fungal culture test that requires growing the organism is another test option.
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"All that takes time," said Dr. Michael Peterson, a pulmonary specialist and head of medicine at the UCSF-Fresno Medical Education Program.
With the new test -- real-time PCR (polymerase chain reaction) -- the DNA signature of the Valley fever fungus can be detected in a matter of hours. PCR copies a section of DNA that can then be tested on the spot.
The test -- performed on a machine at Community Regional Medical Center in downtown Fresno -- became available to patients this month.
The new test won't replace the older, slower ones -- at least for now -- but if it shows a patient has Valley fever, a doctor can start treatment. With negative test results, the doctor can keep looking for other causes of an illness while waiting for results from a blood test, culture or chest X-ray.
A faster diagnostic tool will be useful, said Dr. Claudia Jonah, public health officer for Kern County, the epicenter for Valley fever in California.
However, the challenge is getting doctors to use the test. Too often they don't suspect the fungus is causing a patient's illness, and in many cases the disease is mistaken for bacterial or viral pneumonia, and patients are treated with drugs to no effect, she said.
Valley fever infections, caused from breathing Coccidioides fungal spores, have been increasing at an alarming rate over the past decade, particularly in California and Arizona, where the vast majority of cases occur. Fungal spores also can be found in Utah, New Mexico, Nevada and Texas.
In September, the head of the federal Centers for Disease Control and Prevention and the National Institutes of Health made a trip to Bakersfield where they announced a Valley fever trial to study the best way to treat the fungal disease.
The Fresno PCR test to identify the presence of the fungus is specific to the Coccidioides immitis, the Valley fever fungus species that is unique to California. The state reported more than 4,000 cases in 2012, the latest numbers available -- and more than two-thirds were found in counties between Kern and Merced.
The new test is not the first PCR test for the detection of Valley fever. About eight years ago, the Mayo Clinic in Scottsdale, Ariz., developed a similar testing system for Coccidioides posadasii -- the fungus species found in that state.
But the PCR test at Community Regional is the first to identify the Valley fever fungus that hides in soils in the central San Joaquin Valley, said Dr. Dominic T. Dizon, an associate clinical professor at UCSF-Fresno.
And, to his knowledge, it's the first to use an automated PCR testing system called the BD Max. The machine performs both a DNA extraction process to prepare the sample and runs the real-time PCR test. Completing the extraction and the PCR on the same machine "has never been done" for this organism, Dizon said.
The Fresno test is the brainchild of Dizon and Marilyn Mitchell, supervisor of the microbiology laboratory at Community Regional.
The two collaborated six years ago to develop an alternative test to the decades-old TB skin test.
After their success with the TB test, Dizon and Mitchell began toying with the idea of developing a new Valley fever diagnostic tool. Last year, they got their opportunity when Community Regional got a machine to detect infectious bacteria, such as MRSA -- Methicillin-resistant Staphylococcus aureus -- in patients. MRSA is an antibiotic-resistant bacteria that is contagious and is being seen more often in patients.
Mitchell thought the infectious bacteria testing system could be adapted to include a test for Valley fever and pitched the idea to Dizon. He got a $23,000 grant for the research project from the Central California Faculty Medical Group. Dizon belongs to the group, which is associated with UCSF-Fresno.
The upshot: Patients in the community have a new, fast diagnostic tool for Valley fever available to them. Mitchell expects insurance companies will pay for the test, which costs about $200.
"We made this doable in a general, medical laboratory," Mitchell said.
The test was not created to be commercially marketed and sold to other labs, which would require approval from the federal Food and Drug Administration, Mitchell said. But before it could be available for widespread patient testing, it had to be proven.
Over the past six months, about 250 samples were tested to show there was no interference from other bacteria and fungi that would give false positive results, Mitchell said. There also were no false negatives, she said.
Dizon said the research results will be presented at a meeting in April of the Valley Fever Center for Excellence in Phoenix.
The Mayo Clinic in Scottsdale has used its PCR test for years and has found it's as accurate as culture tests in identifying negative results, said Dr. Janis Blair, head of the Valley fever clinic there. The test, however, hasn't eliminated other tests. "You get the information much sooner than culture," she said. "But it just wasn't the game-changer that we had hoped it would be."
UCSF doctors treating patients in their clinical practices will continue to compare the new test with blood and culture tests, Peterson said. He sees the PCR test, however, as having the potential to help doctors avoid prescribing drugs that patients "don't need and that won't help them."
Hopefully, the test also will allow doctors to "treat earlier with the appropriate antibiotics that we use for Valley fever," Peterson said.
Valley fever patient Dan Kemble of Fresno said he welcomes anything that results in speedier treatment.
Kemble, 59, had been sick with flu-like symptoms for three weeks before he saw a doctor in 2012. The doctor at first thought he had a stomach problem because he was vomiting, but a computer scan of his stomach showed Valley fever nodules in a lower part of a lung. He was put on the antifungal drug, fluconazole, and a blood test confirmed the diagnosis.
But the fungus had spread before he was diagnosed, causing the cotton broker to have neurological problems. He's better now, but Kemble said, "it still hasn't completely gone away."
The earlier he could have started on treatment, the better off he would be, he said. "The key is to get it known quicker -- and to diagnose it -- so you need tools to do that."
Resources for more information
What is polymerase chain reaction (PCR)?
National Institutes of Health: http://www.ncbi.nlm.nih.gov/genome/probe/doc/TechPCR.shtml
Coccidioidomycosis (Valley fever)
California Department of Public Health: http://www.cdph.ca.gov/HealthInfo/discond/Pages/Coccidioidomycosis.aspx
Centers for Disease Control and Prevention: http://www.cdc.gov/Features/ValleyFever/