From the Guidelines
Rocky Mountain spotted fever is a potentially life-threatening bacterial infection that requires immediate treatment with doxycycline, regardless of age, to reduce mortality and morbidity. The disease is caused by Rickettsia rickettsii and transmitted through tick bites, typically presenting with fever, headache, and rash, although the characteristic rash may be absent in early stages or in up to 10-15% of cases 1.
Key Considerations
- The recommended treatment is doxycycline, typically 100mg twice daily for adults and 2.2 mg/kg twice daily for children under 45kg, continuing for at least 3 days after fever subsides and until evidence of clinical improvement (usually 7-14 days total) 2.
- Treatment should begin immediately upon suspicion of the disease, even before laboratory confirmation, as early intervention significantly reduces mortality 1.
- Prevention involves wearing protective clothing in tick-infested areas, using insect repellents containing DEET, checking for ticks after outdoor activities, and removing attached ticks promptly with fine-tipped tweezers.
- Despite its name, Rocky Mountain spotted fever occurs throughout the United States, with higher prevalence in the southeastern and south-central regions, and can be fatal if treatment is delayed 3.
Clinical Presentation
- Symptoms of RMSF typically appear 3–12 days after the bite of an infected tick or between the fourth and eighth day after discovery of an attached tick 3.
- Initial symptoms include sudden onset of fever, headache, chills, malaise, and myalgia, with a rash typically appearing 2–4 days after the onset of fever 3.
- The classic triad of fever, rash, and reported tick bite is present in only a minority of patients during initial presentation to health care 1.
Management and Treatment
- Doxycycline is the drug of choice for the treatment of presumptive or confirmed TBRD in both adults and children 2.
- Limited courses of tetracycline-class antibiotics (e.g., doxycycline) do not pose a substantial threat of tooth staining in children 2.
- Tetracyclines typically are contraindicated for use during pregnancy but might be warranted in life-threatening situations where clinical suspicion of TBRD is high 2.
From the Research
Overview of Rocky Mountain Spotted Fever
- Rocky Mountain spotted fever (RMSF) is a potentially deadly disease caused by Rickettsia rickettsii, transmitted to humans by infected ticks 4, 5, 6.
- The disease can present subtly with signs and symptoms overlapping with other clinical conditions, making diagnosis challenging 4, 5, 6.
Clinical Features
- Symptoms of RMSF include fever, headache, photophobia, malaise, myalgias, and a petechial rash that begins on the wrists and ankles and spreads to the trunk 4, 5, 7.
- The classic triad of fever, headache, and rash is not definitive, and rash may not occur in ≤15% of patients 4.
- Laboratory evaluation may demonstrate hyponatremia, anemia, thrombocytopenia, abnormal liver enzymes, and elevated coagulation tests 4.
Diagnosis and Treatment
- Diagnosis of RMSF is based on the patient's history and physical examination, and often presents a dilemma for clinicians due to the non-specific presentation of the disease in its early course 6.
- Early empirical treatment is essential to prevent severe complications or a fatal outcome, and treatment should be initiated even in unconfirmed cases 6, 8.
- Doxycycline is the treatment of choice in adults, children, and pregnant patients 4, 8.
- Antibiotic therapy should be continued for 7-10 days or until the patient is afebrile for two to five days 5.
Prevention and Morbidity
- Prevention strategies include avoiding tick-infested areas and using effective techniques for removing ticks 4, 5, 6.
- Delayed recognition and treatment of RMSF can lead to severe complications and high mortality rates 8.
- Chronic sequelae, including speech impairment and ataxia, can occur in patients who survive RMSF 8.