An Excessive Heat Warning is in effect on July 23, 2014 for La Paz, Maricopa, Pinal, and Yuma Counties until July 24, 2014 at 8:00 PM. Learn more about how to stay safe in extreme heat and stay informed about future heat alerts.

Rocky Mountain Spotted Fever (RMSF)

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Rocky Mountain Spotted Fever (RMSF) is the most severe disease caused by a tick in the United States. RMSF is a sickness caused by the bite of a tick that has the disease. A majority of RMSF cases in Arizona happen in communities with large number of roaming dogs and a lot of ticks. The first case of RMSF was in 1896 in Snake River Valley, Idaho; however, Arizona has the most cases of RMSF in the U.S.