Haboob_GilbertAZ_Pictowrit_KSM.JPG

A haboob, or dust storm, barrels across the desert near Gilbert, Arizona, in July 2011. Valley fever is caused by the inhalation of fungal spores when soil is disturbed. About 60 percent of U.S. cases of occur in Arizona. (Photo: Pictowrit) A haboob, or dust storm, barrels across the desert near Gilbert, Arizona, in July 2011. Valley fever is caused by the inhalation of fungal spores when soil is disturbed. About 60 percent of U.S. cases of occur in Arizona.