(HealthDay)—Cases of a fungal lung infection called Valley Fever increased sharply in several southwestern states since the late 1990s, according to a report released Thursday.
In Arizona, California, Nevada, New Mexico and Utah, the number of cases climbed from less than 2,300 in 1998 to more than 22,000 in 2011, the U.S. Centers for Disease Control and Prevention found.
During that time, Arizona and California had the largest average increases in Valley Fever incidence, at 66 percent and 31 percent per year, respectively.
Valley Fever (Coccidioidomycosis) is caused by inhaling a fungus called Coccidioides, which lives in the soil in southwestern states. Not everyone who is exposed to the fungus gets sick, but those who do become ill typically have flu-like symptoms that can last for weeks or months.
More than 40 percent of patients who get sick may require hospitalization, with an average cost of nearly $50,000 per visit. And research has shown that 75 percent of those who get sick miss work or school for about two weeks, the CDC said.
Between 1998 and 2011, nearly 112,000 cases of Valley Fever were reported in 28 states and Washington, D.C., but 66 percent of the cases were in Arizona, 31 percent were in California, 1 percent were in Nevada, New Mexico and Utah, and about 1 percent were in all other states combined.
More research is needed to determine what is causing the increase in Valley Fever and how to reduce its effects, the CDC said. Possible reasons could be population growth, weather changes that could affect where the fungus grows and how much of it is circulating, or changes in the way the disease is detected and reported to the CDC.
"Valley Fever is causing real health problems for many people living in the southwestern United States," Dr. Tom Frieden, director of the CDC, said in an agency news release. "Because fungus particles spread through the air, it's nearly impossible to completely avoid exposure to this fungus in these hardest-hit states. It's important that people be aware of Valley Fever if they live in or have traveled to the southwest United States."
Doctors and patients need to be aware that the symptoms of Valley Fever are very similar to flu or pneumonia symptoms, the CDC said. A lab test is the only way to diagnosis Valley Fever.
Not everyone who gets Valley Fever requires treatment, but early diagnosis and treatment are important for those at risk for the more severe forms of the disease. Those at higher risk for severe disease include people of Asian descent (particularly Filipino), blacks, pregnant women and people with weakened immune systems, according to the CDC website.
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The American Lung Association has more about Valley Fever.