| Subject | Contents |
| Definition | An infectious disease caused by Rickettsia rickettsii transmitted to humans by the bite of ticks . |
| Alternative Names | Spotted fever |
| Causes, incidence, and risk factors | In the western U.S., the causative agent R rickettsii is transmitted by the wood tick , and in the eastern U.S., by the dog tick. Other ticks transmit the infection in the southern U.S. and in Central and South America. Contrary to the name "Rocky Mountain" most recent cases have been reported in the eastern United States: North and South Carolina, Virginia, Maryland, Georgia, Tennessee, and Oklahoma. Most cases occur in the spring and summer with about 1,000 cases reported per year. Most of the reported cases have been in children. The risk factors include recent hiking or exposure to ticks in an endemic area. |
| Symptoms | fever chills incubation period of 2 to 14 days severe headachemuscle pain mental confusionrash , first appearing on wrists and ankles, then spreading to most of the body, usually starts a few days after fever starts; up to 20% of people do not get a rash Additional symptoms that may be associated with this disease: thirst, excessivenausea and vomitinghallucinationsdiarrhea appetite, loss abnormal sensitivity to light |
| Signs and tests | low platelets low red blood cell count in 30% of patients possible renal failure, elevated creatinine possible clotting problems, elevated PT and PTT blood in the urine and protein in the urineantibody titer by complement fixation or immunofluorescence that indicates the presence of infection skin biopsy at the site of the rash may show the Rickettsia rickettsii |
| Treatment | The objective of treatment is careful removal of the tick from the skin and antibiotics to eliminate the infection. Doxycycline or tetracycline are frequently used. Chloramphenicol may be used in pregnant women.
Note: oral tetracycline and doxycycline is usually not prescribed for children until after all the permanent teeth have erupted because it can permanently discolor teeth that are still forming. For this disease, it may be used for short periods of time when it is felt that the risks outweigh the benefits.
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| Expectations (prognosis) | Treatment usually cures the infection. Complications are rare but can include paralysis, hearing loss, and nerve damage. The death rate is 5 to 7% and usually reflects a delay in seeking treatment. |
| Complications | pneumonitis respiratory or cardiac failuremeningitis brain damage clotting problems kidney failure shock |
| Calling your health care provider | Call your health care provider if symptoms develop after exposure to ticks or known tick bite . The complications of untreated Rocky Mountain spotted fever can be life threatening. |
| Prevention | When walking or hiking in tick-infested areas, tuck long pants into socks to protect the legs, and wear shoes and long sleeved shirts. Ticks will show up on white or light colors better than dark colors, making them easier to remove from clothing. Remove ticks immediately by using a tweezers, pulling carefully and steadily. Insect repellent may be helpful. Because less than 1% of ticks carry this infection, antibiotics are not usually given after a tick bite if there is no evidence of disease. There is not vaccine against this disease. |
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