Coccidioidomycosis Cases on the Rise in Parts of US

Miriam E. Tucker

March 28, 2013

Reported coccidioidomycosis cases in the United States have risen considerably since 1998, according to new data from the Centers for Disease Control and Prevention (CDC).

The findings were published March 29 in the CDC's Morbidity and Mortality Weekly Report.

Coccidioidomycosis is an infection caused by inhalation of Coccidioides spp spores. The fungus is endemic in dry regions of the southwestern United States. Also known as "Valley Fever," the disease usually causes flulike symptoms that are self-limited, but some patients experience severe or chronic pulmonary disease. Disseminated disease occurs in fewer than 1%.

"Health-care providers should be aware of this increasingly common infection when treating persons with influenza-like illness or pneumonia who live in or have traveled to endemic areas," the CDC says.

Data from the CDC's National Notifiable Diseases Surveillance System indicated a substantial increase in reported cases of coccidioidomycosis in the 4 endemic states (Arizona, California, New Mexico, and Utah), from 5.3 per 100,000 population in 1998 to 42.6 per 100,000 in 2011.

During this time, nearly 112,00 cases of coccidioidomycosis were reported from 28 states and Washington, DC, but only 1% came from states other than the 4 endemic states.

The incidence was highest among people aged 40 to 59 years in California, but in the other 3 endemic states, it was greatest among those aged 60 and older.

In Arizona, the statistically significant increase from 1474 cases in 1998 to 16,467 in 2011 (P < .001) corresponded to an increase of about 16% per year during the study period, after adjustment for demographic factors. In California, that increase was 13% per year, and was also statistically significant (P < .001).

"Valley Fever is causing real health problems for many people living in the southwestern United States," said CDC Director Tom Frieden, MD, MPH, in a 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 travelled to the southwest United States."

Why the Increase?

The reasons for the increase are not clear, but it might have to do with environmental changes to the soil in which the Coccidioides spores reside, or disruption of soil by human activity, such as construction. Changes in reporting or laboratory methods might have played a role, but probably do not fully explain it, the CDC says.

Despite the rise in incidence, mortality rates have remained fairly stable, at approximately 0.6 per 1 million person-years during 1990-2008.

Antifungal treatment is recommended for certain patient groups who are at high risk for severe disease. Because the symptoms of coccidioidomycosis are similar to those of other respiratory illnesses, awareness of the condition and testing to receive a diagnosis can help avoid unnecessary antibiotic prescriptions.

"Therefore, promoting increased community and health-care provider awareness of this infection continues to be an important role for public health officials," the CDC says.

More information is available at

MMWR. Published online March 26, 2013. Full article