Atypical presentation of Rocky Mountain Spotted Fever

Rocky Mountain spotted fever was initially identified in the Rocky Mountain region. However, RMSF cases are now reported throughout the nation, with higher incidence in the southeastern and south-central regions.

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 was admitted to the hospital with a fever, generalized weakness with myalgia, persistent hiccups, confusion and agitation.¹

A physical exam revealed the patient exhibited tachycardia, tachypnea, elevated blood pressure, and a high fever of 103.3°F. Test results showed severe hyponatremia (an electrolyte abnormality), leukocytosis, and abnormal blood parameters.

Initial treatment for sepsis

The man’s symptoms improved after he was treated with IV ceftriaxone for sepsis due to a urinary tract infection or pneumonia.

However, the patient later developed a 106.5°F fever and was admitted to the ICU.

“Upon further history-taking to determine the source of a fever of unknown origin, the patient revealed a potential exposure to ticks and a cat suspected of having lice one week prior.”

He was subsequently tested for Bartonella, Borrelia burgdorferi, and Rickettsia (the bacterium which causes Rocky Mountain spotted fever).

As a precaution, the patient was treated empirically with doxycycline for a possible tick-borne illness and released from the hospital.

Although initial testing was inconclusive for a tick-borne illness, follow-up testing was positive for Rickettsia.

“This case report underscores the diagnostic challenges posed by atypical presentations of RMSF and emphasizes the critical importance of early detection and treatment to prevent severe complications.”

Rocky Mountain spotted fever – key points:

• RMSF typically manifests with vague symptoms including fever, headache, rash, muscle pain, and nausea.
• Test results are often within normal ranges in the early stages of disease. According to the authors, “it may take several weeks to obtain confirmatory diagnostic outcomes.”
• “Atypical manifestations of RMSF, such as generalized neurologic complaints, myocarditis, or visual disturbances, are not well characterized in the literature. Healthcare providers should consider RMSF in the differential diagnosis of patients with these manifestations.”