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If you live in the Southwest, you have a greater chance than most Americans of developing a rare lung condition called Valley fever. Caused by the spores from a particular kind of fungus, valley fever is sometimes referred to as “the great imitator,” because its symptoms mimic those found in other conditions, including lung cancer.

“Valley fever is a pulmonary disease caused by the inhalation of an environmental fungus called Coccidioides, which is typically found where there are hotter, dryer soils,” explains David Engelthaler, Ph.D., professor and director of the Division of Immunology and Microbial Genomics at the Translational Genomics Research Institute (TGen), an affiliate of City of Hope® Cancer Center Phoenix.

While there are around 300,000 new cases every year, Valley fever is more common in the southwestern United States than anywhere else worldwide.

“We see it primarily in the central and southern portions of Arizona and California — these are the most endemic regions for this disease in the world,” Dr. Engelthaler adds.

This article covers the basics on valley fever:

If you or a loved one has been diagnosed with lung cancer and are looking for a second opinion, call us 24/7 at 877-524-4673.

What Is Valley Fever?

Valley fever is a lung condition that develops when someone breathes in the spores from a fungus called Coccidioides and those spores cause a fungal infection in the lungs. It is sometimes called coccidioidomycosis, San Joaquin fever or desert rheumatism.

While the disease has been found in other parts of the world, most cases occur in Arizona and Southern California – most commonly the San Joaquin Valley, after which the disease is named.

“This fungus is in the soils throughout the Southwest, but it’s not everywhere. You could find it in one area and then go a few feet away and it won’t be there,” Dr. Engelthaler explains. “We don’t know exactly where the fungus is and how it gets up into the air, which makes it hard to create effective interventions.”

Although it is hard to predict where and how Coccidioides spores find their way out of the desert soil, it can be caused by:

  • Disturbing soil during gardening
  • Certain kinds of agricultural activity
  • Construction that involves digging into the soil

There appears to be a strong connection between Valley fever and rodents. Mice and rats that live in natural desert and agricultural areas can contract the fungus. When they die in burrows their bodies release Coccidioides into the soil, spreading the fungus to a potentially new place.

Valley Fever in Arizona

With its dry, desert environment, Arizona offers the perfect conditions for the Coccidioides fungus to thrive. The Centers for Disease Control and Prevention reports that Arizona healthcare providers detect around 10,000 cases of Valley fever every year — but the true numbers may be drastically higher, since this number only accounts for the number of infections that are confirmed by testing.

“According to one study, up to a third of people with what is considered walking pneumonia, in endemic areas, actually have Valley fever,” says Dr. Engelthaler. “But only about 20% to 30% of people with pneumonia are ever tested, so we’re missing a wide swath of individuals who may have the condition.”

Unlike a bacterial infection or a virus, Valley fever is treated with antifungal medications. This means it is important to correctly diagnose the condition.

“We need to do more health care education, so physicians are ordering tests for people who have Valley fever symptoms,” says Dr. Engelthaler. “This will help clinicians in the Southwest understand that this is the disease of the region.”

Valley Fever Symptoms

More than half of all people with Valley fever do not know they have the condition. They may experience no symptoms or mild cold- or flu-like symptoms such as:

  • Coughing or shortness of breath
  • A fever
  • Muscle and joint pain
  • Fatigue
  • Night sweats or chills

“However, 10-20% of people develop a more serious pulmonary infection similar to walking pneumonia,” Dr. Engelthaler says. “These people are out of commission for several weeks, but after this, they’re probably immune for the rest of their lives.”

In a very small percentage of cases, the Valley fever fungus may invade other parts of the body. This may lead to more serious conditions, such as meningitis, and require lifelong treatment; or even lead to a fatal outcome.

Can Valley Fever Be Misdiagnosed as Cancer?

According to Dr. Engelthaler, Valley fever is often wrongly identified. Since Valley fever may cause both flu symptoms and a lung infection, the most common misdiagnosis is bacterial pneumonia. However, the condition may also be mistaken for lung cancer.

There are also cases of Valley fever being misdiagnosed as cancers like lymphoma and ovarian cancer, although this is less common.

“Often, Valley fever is misidentified as potential lung cancer after people go in for a chest X-ray and the scan shows a spot on their lungs,” says Dr. Engelthaler.

Does Valley Fever Cause Lung Nodules?

A lung nodule, also called a granuloma, is a small cluster of cells inside the lung. Nodules develop in response to some kind of infection and are usually made up of immune cells that cover the infected area. When the fungal spores that cause Valley fever infect the lung, this may lead to lung nodules.

Many lung nodules are not cancerous. If a chest scan reveals a lung nodule, it is important to have it evaluated by a lung health or lung cancer expert to determine whether it is caused by cancer, Valley fever or another condition. This enables doctors to recommend the right course of action and — in the case of Valley fever — avoid an unnecessary biopsy, which could open a lung nodule and cause the disease to spread.

Getting a Diagnosis at City of Hope Phoenix

The best way to ensure an accurate diagnosis and to screen for signs of lung cancer is to see a cancer specialist. City of Hope Phoenix offers advanced lung cancer screening, including a rapid lung nodule diagnosis that provides results quickly and accurately and can distinguish between cancer and other conditions like Valley fever.

At TGen, Dr. Engelthaler’s team continues to work on finding better means of testing for and treating “the great imitator” itself: Valley fever.

“We want to make sure we’re doing as much as we can to understand when and where people are getting exposed to this condition, so we can limit that exposure,” he says.

This includes working on research projects targeting better antifungal treatments, vaccines and more reliable screening methods, including the only PCR test approved by the Food and Drug Administration for diagnosing Valley fever. His work also includes research to better understand when, where and why people become exposed to the fungus.

“But we’re also working to ensure clinicians are thinking about Valley fever when they live in an endemic region.”

If you or a loved one has been diagnosed with lung cancer and are looking for a second opinion, call us 24/7 at 877-524-4673.