The disease gets its name from the Rocky Mountain area where it was first identified. Rocky Mountain spotted fever is caused by Rickettsia rickettsii, a specialized bacteria. Ticks infected with the organism transmit the disease to humans. Rocky Mountain spotted fever is found throughout the United States, except in Maine, Alaska, and Hawaii. Despite the name, few cases are reported from the Rocky Mountain region.
Most cases occur in the southeastern United States.
Rocky Mountain spotted fever is spread by the American dog tick, the lone-star tick, and the wood tick, all of which like to live in wooded areas and tall, grassy fields. The disease is most common in the spring and summer when these ticks are active, but it can occur anytime during the year when the weather is warm. People get Rocky Mountain spotted fever from the bite of an infected tick or by contamination of the skin with the contents of an attached tick when it is removed from the skin. Rocky Mountain spotted fever is not spread from person to person, except rarely by blood transfusion. The rash might begin on the legs or arms, can include the soles of the feet or palms of the hands, and can spread rapidly to the trunk or the rest of the body.