Anaplasmosis Mimicking Acute Cholecystitis

Author(s):
Hannah Medeck; Kurt Stahlfeld; Margaret Miller

Background:

Introduction: Anaplasmosis is a tick-borne Rickettsial disease caused by Anaplasma Phagocytophilum, an obligate intracellular gram-negative bacterium transmitted via the Ixodes Scapularis tick. Most prevalent in the east coast states, the incidence has increased ten-fold in the last two decades. (1) Treatment is with doxycycline, although the diagnosis is often delayed because the presenting symptoms mimic those of more common illnesses.

Hypothesis:

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Methods:

Case: A 60 year old male with a history of atrial fibrillation, GERD, and hypertension presented with five days of severe right upper quadrant abdominal pain radiating to his back, nausea, fever, chills, malaise, and dark urine. His laboratory studies revealed pancytopenia, transaminitis, and hyperbilirubinemia. Imaging studies demonstrated a nondistended gallbladder with wall thickening, pericholecystic fluid, porta hepatis inflammation, and a normal sized common bile duct without stones. Hepatobiliary scan was not performed as the radiotracer is not available on weekends. A combined surgery/radiology consult suggested a disseminated, possibly tick-borne, infection. Infectious disease started empiric antibiotic therapy, and serologies eventually returned positive for Anaplasma Phagocytophilum. He recovered quickly from his illness and was discharged home.

Results:

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Conclusions:

Discussion: Anaplasma phagocytophilum targets host granulocytes, upregulating proinflammatory cytokines while simultaneously inhibiting neutrophil antimicrobial function. (3,4) While anaplasmosis typically causes self-limiting symptoms such as fever, chills, nausea, headache and myalgias, antibiotics should be started with suspicion of this tickborne illness as severe complications have been reported, including ARDS, coagulopathies, neuropathies, pancreatitis, rhabdomyolysis, and acute renal failure. Severe pancytopenia and transaminitis are characteristic laboratory findings. (2) Diagnosis during the acute stage is by PCR. As there are high rates of co-transmission with other Rickettsial diseases, serology should cast a wide net. (3) Treatment is with Doxycyline. The course of this patient, who was transferred urgently with a diagnosis of acute cholecystitis, demonstrates the importance of a detailed history, familiarity of seasonal tickborne illnesses, and a high suspicion in patient with acute illnesses after outdoors exposure in areas endemic to Rickettsial diseases.