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CDC: Dramatic increase in valley fever in southwestern US
The CDC has reported a dramatic increase in valley fever in several southwestern states from 1998 to 2011.
“It’s difficult to say what’s causing the increase,” Benjamin J. Park, MD, chief epidemiologist with the CDC’s Mycotic Diseases Branch, said in a press release. “This is a serious and costly disease and more research is needed on how to reduce its effects.”
Using data from the National Notifiable Diseases Surveillance System, the CDC analyzed the incidence of valley fever (coccidioidomycosis) from 1998 to 2011. They found that the incidence increased from 5.3 cases per 100,000 population in the endemic area in 1998 to 42.6 cases per 100,000 population in 2011. The endemic area includes Arizona, California, Nevada, New Mexico and Utah.
According to the report in Morbidity and Mortality Weekly Report, valley fever is caused by inhalation of the soil-dwelling fungus Coccidioides. Patients with the disease typically only experience an influenza-like illness, but some develop severe pulmonary disease. Less than 1% of patients have disseminated disease. More than 40% of patients with valley fever require hospitalization at some point.
“Valley fever is causing real health problems for many people living in the southwestern United States,” CDC Director Tom Frieden, MD, MPH, said in a press 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.”
Although more research is necessary to determine exactly why the incidence of valley fever has increased, it could be related to changes in weather, higher numbers of new residents or changes in the way the disease is detected and reported, according to the press release.
Perspective
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Coccidioides spp. are soil-dwelling fungi which exist solely in the semiarid to arid life zones of the southwestern United States, Mexico, and parts of central and South America. Several areas of the United States are considered “hyperendemic” including Bakersfield, Calif., and both Phoenix and Tucson, Ariz.
In these regions, up to one-fourth of all cases of community-acquired pneumonia are actually caused by coccidioidomycosis (cocci) and not by bacterial or viral infections. Despite the frequency of infection, current community-acquired pneumonia guidelines are largely silent on testing for coccidioidomycosis and prior reports have shown only 2% to 10% of patients are even tested for this condition. Some advocate for routine Coccidioides serologic testing in all patients with community-acquired pneumonia within the endemic region, while others reserve testing for those with pneumonia, rash and/or eosinophilia — factors that increase the pre-test probability of coccidioidomycosis.
This report confirms how common the infection is, suggests that infection rates may be increasing for reasons that are not yet entirely clear, and reiterates the importance of considering coccidioidomycosis in those residing within or returning from the endemic region.
The rising incidence of infection mandates that several fundamental questions be answered: Do patients with primary coccidioidal pneumonia benefit from antifungal therapy? Why is there a higher risk of disseminated infection in Filipino and African-American patients? Knowing the answers to these questions may help to alter the course of disease in selected patients, and potentially reduce the morbidity and mortality that can be associated with this infection.