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Rocky Mountain Spotted Fever (RMSF)

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Rocky Mountain spotted fever (RMSF) is the most severe tick-borne rickettsial illness in the United States, with up to 25% fatality in untreated patients. This disease is caused by infection with the bacterial organism Rickettsia rickettsii (rick-ETT-cee-uh rick-ETT-cee-eye). First record of the disease was in 1896 in Snake River Valley, Idaho, but today few cases occur in the Rocky Mountain region. Each year from 2002 to 2009, between 1,091 and 2,563 cases of RMSF occurred in the United States. Over 100 cases of RMSF have been reported in Arizona since 2006, with most RMSF cases reported in eastern Arizona. Almost all RMSF cases in Arizona occur in communities with a lot of free-roaming dogs and severe tick infestations.

For more information on Rocky Mountain spotted fever, see the fly-out links on the left.

Rocky Mountain Spotted Fever - 2009 map
This map shows the number of Rocky Mountain spotted fever cases in the USA in each county in 2009.
(Courtesy of Centers for Disease Control and Prevention.)