Rocky Mountain spotted fever is a disease caused by ticks that carry the Rickettsia rickettsii bacterium. This bacterium is spread to humans through tick bites. There are several species of ticks in the U.S. that can spread the disease; however, in the eastern U.S. the bacteria are carried by dog ticks, and in the western states, by the wood tick. Rocky Mountain spotted fever most commonly occurs in Arkansas, Georgia, Virginia, Missouri, North and South Carolina, Tennessee, Virginia, and Oklahoma. Most cases occur in the spring and summer in children. If untreated, the infection can lead to serious health problems, such as brain damage, kidney and heart failure, meningitis, and pneumonitis. Rocky Mountain spotted fever can be life-threatening if not treated early.

Symptoms of Rocky Mountain spotted fever appear 2-to-14 days after a tick bite and include chills and fever, confusion, headache, muscle pain, rash that first appears as spots and then spread, thirst, lack of appetite, diarrhea, light sensitivity, hallucinations, loss of appetite, nausea and vomiting, and abdominal pain.

Treatment first involves removing the tick carefully without touching it. Antibiotics, such as doxycycline or tetracycline, are needed. Pregnant women are prescribed chloramphenicol. Early treatment can prevent severe illness and death.