Causes

Rocky Mountain spotted fever is caused by infection with the organism Rickettsia rickettsii. Ticks carrying R. rickettsii are the most common source of infection.

If an infected tick attaches itself to your skin and feeds on your blood for six to 10 hours, you may pick up the infection. But you may never see the tick on you.

Rocky Mountain spotted fever primarily occurs when ticks are most active and during warm weather when people tend to spend more time outdoors. Rocky Mountain spotted fever cannot be spread from person to person.