Rocky Mountain spotted fever diagnosis can be challenging, especially with atypical presentations. Rocky Mountain spotted fever has primarily been reported in 5 states in the United States, according to the CDC. These include Missouri, Tennessee, Oklahoma, Arkansas, and North Carolina. However, RMSF has been documented in other states, as well.

The disease can be transmitted by various ticks depending upon the region. In the eastern U.S., it’s transmitted by the American dog tick; in the Rocky Mountains, by the Rocky Mountain wood tick and in parts of southwestern U.S., it’s transmitted by the brown dog tick.

Case presentation

In their article, “Unconventional Rocky Mountain Spotted Fever Presentation From Kentucky: A Compelling Case Report and Literature Review,” Hussain and colleagues describe the case of a 71-year-old man who developed fever, generalized weakness with myalgia and persistent hiccups over a 2-day period.¹ His condition progressed and when admitted to the hospital, he displayed increasing confusion and agitation.

“The decision to initiate treatment hinges on clinical suspicion and failure to promptly administer appropriate therapy during the first five days of illness is associated with elevated mortality rates.”

Initial treatment and complications

The patient’s condition improved after he was treated for sepsis, which included IV ceftriaxone. However, he subsequently developed a fever of 106.5 F and was transferred to the intensive care unit.

After further discussions, the patient revealed he had been exposed to ticks and a cat suspected of having lice, one week prior to his symptom onset.

He was tested for Bartonella, Borrelia burgdorferi (Lyme disease) and Rickettsia.

Rocky Mountain spotted fever diagnosis confirmed

“Initial tests and treatments did not reveal a cause, but later, after possible tick and lice exposure, he tested positive for Rickettsia and was prescribed prophylactic doxycycline,” the authors wrote.

“Empiric treatment with doxycycline was initiated, which played a pivotal role in preventing potential complications,” the authors point out.

This case illustrates why Rocky Mountain spotted fever diagnosis requires clinical judgment, as test results may not be available within the critical first five days.

Authors’ takeaways

• “Diagnostic results are typically unavailable within the first five days, emphasizing the pivotal role of clinical judgment in prompt intervention.”
• Healthcare providers should consider RMSF even in the absence of tick exposure, fever, or rash.
• “Although fever has traditionally been a diagnostic hallmark, its absence should not preclude clinical consideration, especially in endemic regions when patients otherwise exhibit compatible symptoms.”
• Because the patient initially presented with a fever which then resolved, clinicians redirected their attention away from the initial suspicion of a rickettsia infection.
• Patients can have atypical presentations of RMSF, such as generalized neurologic complaints, myocarditis, or visual disturbances.
• The diagnosis was particularly challenging given the patient had neurologic manifestations involving confusion and agitation.