|
Rocky Mountain Spotted Fever (RMSF)
Rocky mountain spotted fever (RMSF) is the second most common tick-borne disease in the United States. This disease, caused by bacteria, is transmitted through the infected bite of the wood tick found in the west, and the American dog tick in the southeast. It was first recognized in the northwestern United States in the 1700's, but due to a geographic shift, it now occurs in southern and eastern portions of the U.S.. Peak incidence for RMSF is from late spring to early fall. Approximately two-thirds of patients remember having a tick bite. Between 500 and 1,000 cases of RMSF are reported annually, with peak rates in the south Atlantic region (32%) and the west-south-central region (24%). Symptoms of RMSF vary with fever, rash, extremity swelling, headache, nausea, vomiting, cough, and muscle aches. RMSF can result in encephalitis, myocardial necrosis (heart muscle destruction), and respiratory complications (pneumonia). Severe cases may result in shock and kidney failure. Symptoms develop 2-14 days (average 5) after exposure. Initial symptoms are fever and rash (red and flat, progressing to a deep red/dusky color). The rash can later proceed to appear more raised. Rash is present in 75-80% of cases and begins on the flexor surfaces of the wrists and ankles then it spreads to the trunk. Diagnosis is difficult, even for the experienced physician. Serologic blood testing using a fluorescent antibody titer can be performed, but is often negative early in the disease. Skin biopsy (at the rash site) can yield sensitive and specific results if subjected to immunologic testing. Treatment of suspected RMSF should include IMMEDIATE treatment with tetracycline or chloramphenicol for at least 10 days. Tick removal will be necessary. Hospitalization is highly recommended in the initial course of this illness.
|
