Tucson has an abundance of rattlesnakes, scorpions and cacti, but one of its greatest health hazards is a fungus that lives in the dirt.

Last year more than 10,000 Arizonans found out just how dangerous Coccidioides immitis is when they were diagnosed with valley fever, a fungal infection that can result when airborne spores from the mold are inhaled.

Next Sunday, a group of Tucsonans is fighting back with the Walk to Cure Valley Fever from 8 to 11 a.m. on the University of Arizona Mall.

"The actual number of people suffering from valley fever is probably 30,000 (annually) in Arizona because it is vastly under-diagnosed," said Dr. John Galgiani, director of the Valley Fever Center for Excellence at the UA.

"In the United States as a whole, the numbers I cite are 50,000 infections a year and two-thirds of those occur in Arizona. Almost all of those are between here and Phoenix along I-10; that is why we call this the 'Valley Fever Corridor.' "

Diana Wilkinson, chairwoman of the upcoming walk, became a statistic two years ago after mistaken diagnoses of pneumonia and stage-three lung cancer. Following surgery to remove a portion of her lung, doctors found she had valley fever.

"I was told definitively I had lung cancer and it was valley fever, so there is a problem with diagnostics and education. I discovered this happens a lot: People are misdiagnosed and treated with the wrong medications," said Wilkinson, who racked up about $50,000 in health-related expenses and missed more than a month of work due to her illness.

She is not alone: While 60 percent of those who develop valley fever have zero or mild symptoms and develop immunity, the rest can be symptomatic for months or years.

Common symptoms include fatigue, cough, shortness of breath, fever, headaches, rash and joint and muscle aches.

Wilkinson is among the small percentage of people - higher among those who are immunocompromised or pregnant - who develop serious symptoms that can be life-altering or deadly.

Galgiani said the cost is significant: a study by the Arizona Department of Health Services tracked $86 million in hospital costs due to valley fever in 2007.

About $6 million is spent annually to treat animal companions such as dogs, cats, alpacas, horses and llamas who contract the disease.

"About one in 25 dogs within Maricopa and Pima counties will be sick every year with valley fever, so the numbers are exponentially larger in the pet community," said Dawn Vandaveer, who joined the all-volunteer Valley Fever Alliance in support of the Center for Excellence when her dog contracted the disease several years ago.

Galgiani and the volunteers believe education - in the medical community and the public at large - is key to improving management of the disease.

"Patients need to know valley fever exists. Doctors will pay more attention if patients ask about valley fever. And people should know that if they visit Arizona and go back to Poughkeepsie and end up with pneumonia, they have a 30 percent chance that pneumonia is something they picked up here as a fungal infection," Galgiani said.

He also hopes that increased public awareness will lead to increased funding for research into new methods of diagnosis and possible vaccines or cures. A frontrunner is Nikkomycin Z, a "very promising" drug under development at the University of Arizona that Galgiani said has been effective in experimental treatments on mice and appears to have no adverse side effects for humans.

Wilkinson and Vandaveer, who have felt the personal impact of valley fever, are determined to help bring Nikkomycin Z to clinical trials.

"It will cost anywhere from $20 million to $70 million to bring the drug to the marketplace and it can be used for humans as well as animals," Vandaveer said. "That sounds like a lot, but in the whole scheme of things when you look at how much is spent each year treating valley fever, it is not."

If You Go

• What: The Walk to Cure Valley Fever to benefit the Valley Fever Center for Excellence.

• When: 8 to 11 a.m. Oct. 10. Registration begins at 8 a.m.; the walk begins at 9 a.m.

• Where: University of Arizona Mall.

• Cost: $25 per person.

• Etc.: Festivities include a canine-friendly walk around the Mall, a Walk for Valley Fever cap for each entrant (and a bandanna for each canine entrant), children's crafts, educational outreach and an Agility Express Fun Course for dogs of all skill levels. (Dogs must be leashed and in compliance with Pima County Animal Control laws.)

The cost for one turn around the agility course is $5; $10 for three turns.

Proceeds from the Agility Express benefit the Valley Fever Companion Animal Fund.

Other activities include the Best In Show "Pupcake" Contest, featuring a cupcake-decorating contest with four categories of "breeds" susceptible to valley fever: dogs, cats, humans and "other" such as cattle, horses, llamas, alpacas, zoo animals, marine animals and wildlife.

Entry fee is $10 per pupcake. For a complete list of contest rules or online registration, go to http://sites.google.com/site/tucson2010walkforvalleyfever/pupcakes-contest and for more information on the walk, visit www.vfever.org or call 626-6517.

Contact Loni Nannini at ninch2@comcast.net