Valley fever cases have skyrocketed in California and other Southwestern states, according to the U.S. Centers for Disease Control and Prevention.
There were more than 22,000 cases in 2011 in California, Arizona, Nevada, New Mexico and Utah, up from 2,265 in 1998, according to a CDC report released Thursday.
Of all the cases reported nationwide between 1998 and 2011, 66% were in Arizona and 31% were in California.
Valley fever is a fungal respiratory infection and can lead to flu-like symptoms that can last weeks. About 40% of those who get sick may require hospitalization, according to the CDC. A lab test is required for diagnosis.
CDC Director Tom Frieden said in a statement that the fungus "is causing real health problems for many people living in the southwestern United States."
California and Arizona have received grants to study reasons for the increase.