Case Presentation: A 72-year-old man with a history of Crohn’s disease and hypertension presented to the emergency department with one month of worsening fatigue, anorexia with weight loss and headaches. The patient also noted intermittent high-grade fever up to 105 degrees Fahrenheit of one week’s duration.One month before presentation, the patient had returned to NYC from upstate NY in the Catskill Mountains where he had stayed for 5 months from March to August. During his stay, he remained active with many outdoor activities. He denied any insect or tick bite. Three weeks prior to presentation, patient was seen by his primary care physician. At the time laboratory results showed normal blood counts and kidney and liver function. The day before presentation, repeat blood tests at the primary care office revealed new pancytopenia, for which he was sent to the emergency department and admitted to the hospital for further evaluation. His home medications included mesalamine, amlodipine, lisinopril, and acetaminophen. He was not on any immunosuppressive agents. On physical exam, vital signs were normal. There was hepatosplenomegaly, and no rash was seen throughout his body. Laboratory testing revealed pancytopenia with leukocyte count of 2.7 x 109/L, hemoglobin of 10.1 g/dL, and platelet count of 36 x 109/L, AKI, transaminitis, and elevated CRP. Additional blood tests showed elevated LDH of 589 IU/L and undetectable haptoglobin, which were suggestive of hemolytic anemia.Giemsa-stained blood smear showed the ring forms of Babesia spp. with 1.5% parasitemia. Babesia microti was confirmed by PCR. IgG titer was 1:320. Infectious serology testing was positive for Lyme EIA subsequently confirmed with Western blot, but otherwise negative for HIV, HAV, HBV, HCV, EBV, CMV, parvovirus B19 and Anaplasma phagocytophilium. Patient was treated with a 10-day course of atovaquone and azithromycin for babesiosis, as well as amoxicillin for Lyme infection as he is allergic to doxycycline. Patient responded well to the antibiotic regimen with no detectable parasitemia upon discharge. At the outpatient follow-up visit, repeat CBC showed the resolution of his pancytopenia.
Discussion: Human babesiosis is a tick-borne infection caused by the intraerythrocytic protozoan species of the genus Babesia. This case illustrates the hematologic manifestations of babesiosis, which are most characterized by hemolytic anemia and splenomegaly.(1) Anemia is caused by the rupture of erythrocytes during egress of babesia and also by nonhemolytic mechanisms such as the clearance of uninfected erythrocytes.(2) This non-autoimmune hemolysis due to babesiosis is known to resolve with antibiotic treatment and clearing of parasitemia. Thrombocytopenia is common and leukopenia may occur. In our case, splenomegaly secondary to babesiosis likely contributed to the development of pancytopenia. In this case, concurrent Lyme disease was found and treated. In the northeastern part of the US, babesiosis is typically caused by B. microti which is transmitted by the tick, Ixodes scapularis. This is the same tick vector responsible for transmission of anaplasmosis and Lyme disease. Thus, co-infection with Anaplasma phagocytophilium and Borrelia burgdorferi should always be considered and tested for when treating babesiosis.(3)
Conclusions: Babesiosis should be suspected in febrile patients with hemolytic anemia in the setting of epidemiologic risks. Travel history is vital to differentiate febrile illness.