Valley Fever on the Rise: CDC Study

Cases of valley fever have increased significantly between 1998 and 2011 in many south-western states, according to a Centers for Disease Control and Prevention study.

The cases of valley fever or Coccidioidomycosis rose from 2,265 in 1998 to over 22,000 in 2011 in states including Arizona, California, Nevada, New Mexico and Utah.

The fever is caused by a fungus called Coccidioides, which is found in the southwestern US. Not all people exposed to the fungus catch the disease. However, the disease requires urgent medical care in some people who are highly vulnerable to the infection like those with cancer, HIV or people who've had organ transplant.

People infected with the fungus have flu-like symptoms that can last for days or even months. About 40 percent people diagnosed with the fever require hospitalization.

"Valley Fever is causing real health problems for many people living in the southwestern United States. 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," said CDC Director Tom Frieden, M.D.

During the study period, more than 11,000 cases were reported from 28 states and Washington, D.C. However data shows that 66 percent of these cases were reported from Arizona and 31 percent from California. About 1 percent of the cases came from Nevada, New Mexico, and Utah while the cases reported from other states combined made-up 1 percent of all valley fever cases in the U.S.

Researchers say that the increase in valley fever cases could be due to changes in weather, increase in population living in these areas or due to increase in surveillance by the health agencies.

"It's difficult to say what's causing the increase. This is a serious and costly disease and more research is needed on how to reduce its effects," said Benjamin J. Park, M.D., chief epidemiologist with CDC's Mycotic Diseases Branch, according to a news release from the agency.