Acalculous Cholecystitis: An Uncommon Presentation of Babesiosis.

Human babesiosis is commonly caused by Babesia microti, an infectious protozoan with a preference for erythrocytes. We describe a case of babesiosis presenting with acute acalculous cholecystitis. A 74-year-old man with a history of diabetes mellitus presented with four days of fever, chills, dyspnea on exertion, and dark brown urine. A physical exam was notable for scleral icterus. Laboratory findings were significant for lactate dehydrogenase (LDH) of 518, total bilirubin of 7.4, and direct bilirubin of 6.2. Imaging, including abdominal ultrasound, CT abdomen and pelvis, magnetic resonance cholangiopancreatography (MRCP), and hepatobiliary iminodiacetic acid (HIDA) scans, demonstrated acute acalculous cholecystitis. On further history, the patient confirmed a recent hiking trip in Virginia. Further evaluation, including peripheral smear and polymerase chain reaction (PCR), was consistent with Babesia microti infection. Babesiosis is common in the Northeastern and Midwestern United States, and symptoms can range from asymptomatic infection to nonspecific malaise and fever to severe end-organ dysfunction. Diagnosis is via peripheral smear or PCR, which can be confirmed via serology. The combination of clindamycin and quinine or atovaquone and azithromycin are the cornerstones of pharmacotherapy. Acute acalculous cholecystitis is a very uncommon presentation of babesiosis. Babesia infection must be considered in the differential in a patient with nonspecific symptoms living in an endemic area.