Case Report: Rocky Mountain Spotted Fever with Adrenalectomy and a Hard-to-Find Tick

Abstract

BACKGROUND Rocky Mountain spotted fever (RMSF) is a potentially fatal infectious disease caused by the gram-negative intracellular bacterium Rickettsia rickettsii. The classic triad includes fever, rash, and history of tick exposure; however, the triad presents in only 3% to 18% of cases at the initial visit, and the tick bite is often painless and overlooked. RMSF can present with other manifestations, including hyponatremia, lymphopenia, thrombocytopenia, and coagulopathy. Some of these manifestations can be overlooked if they overlap with manifestations of a patient's pre-existing conditions. CASE REPORT A 43-year-old woman with RMSF presented with fever and treatment-resistant hyponatremia before developing a rash. Initially, the cause of her hyponatremia was attributed to adrenal insufficiency and dehydration. After appropriate treatments with hormone replacement therapy and intravenous hydration, her laboratory values remained relatively unchanged. A rash later appeared with an atypical RMSF pattern, warranting a detailed integumentary examination, which uncovered the culprit tick in an unusual location. After starting doxycycline, the patient's signs and symptoms, including her sodium level, improved. CONCLUSIONS We conclude that the diagnosis of RMSF is an empiric diagnosis based on clinical signs, symptoms, and appropriate epidemiologic settings for tick exposures. However, typical clinical signs do not always display at presentation. Other manifestations that a patient's pre-existing conditions can simultaneously cause should not be overlooked and should be examined holistically with other signs, symptoms, laboratory values, and physical examinations. Early treatment with doxycycline is encouraged as evidence strongly suggests that early treatment is correlated with lower mortality.

Figure 1.

Patient’s serum sodium level before, during, and after admission. This graph shows the level of the patient’s sodium levels throughout her hospital stay from day 1 to day 3. The patient was discharged on day 3 and was seen again on day 22 for an oncology follow-up. Despite aggressive management of her adrenal insufficiency, her sodium level did not correct appropriately from day 1 to day 3. After being given doxycycline for RMSF on day 3, her sodium level started to improve steadily and returned to normal by the time she was followed up in the oncology clinic on day 22. The normal sodium level of 135 mmol/L on day -8 is her sodium level 8 days prior to the admission obtained by the oncology clinic and used as the baseline for sodium level.