Case Presentation: A 39-year-old man with no significant past medical history was hospitalized with a 2-week history of constant burning left upper quadrant pain, headaches, myalgias, and fever/chills. The patient reported camping in Pennsylvania 1 month prior to presentation. In the ED, he was initially found to be febrile to 102.4F and hypotensive to SBP 80s, with improvement after administration of intravenous fluids. Physical exam was notable for a tender and palpable spleen 3cm below the diaphragm. Laboratory studies were significant for thrombocytopenia (51 K/uL), mild anemia (12.4 g/dL), elevated LDH, low haptoglobin, and mild transaminitis (AST/ALT 46/50). Blood cultures, HIV testing, and hepatitis testing were negative. CT abdomen showed splenomegaly (15cm) with multiple splenic infarcts. Peripheral blood smear showed 1.2% parasitemia with babesia. He was found to have positive Babesia IgM (>1:320), positive EBV IgM and IgG, and positive Parvovirus IgM (2.0) and IgG, the latter two presumed to be indicative of past recent infection. Testing for Ehrlichia and Lyme were negative. The patient was treated for acute babesiosis; he was started on a 10-day course of atovaquone and azithromycin. The patient’s symptoms and laboratory studies slowly improved, and he was discharged 4 days later with 0.35% parasitemia on peripheral smear. Repeat ultrasound performed 1 month after hospital discharge showed resolution of splenomegaly, and the patient’s symptoms and laboratory studies normalized as an outpatient.
Discussion: Babesiosis is a parasitic infection transmitted by the Ixodes tick and is endemic to the Northeastern US. Fatal disease is a risk in immunocompromised, elderly and asplenic patients. Severe disease typically occurs in older and immunocompromised patients and is characterized by parasitemia >4%. Splenic infarction is a rare but potentially life-threatening complication of babesiosis and can lead to splenic rupture if unaddressed. While the mechanism remains unclear, microthrombi formation in small vessels and/or vascular obstruction by parasitized RBCs have been speculated as possible causes. This case of a young, immunocompetent male demonstrates that severe complications can manifest even in mild-moderate disease in patients without significant risk factors. Perhaps this is owing to a robust and therefore more caustic immune system. Of notable consideration in this case were the patient’s concurrent positive parvovirus IgM and EBV IgM antibodies, both of which can persist up to 4 months after inoculation. Both mononucleosis and parvovirus infection can cause hematologic abnormalities with resulting splenomegaly, raising the question of whether our patient’s recent infection with these viruses may have contributed to his unusually severe presentation.
Conclusions: Splenic infarction is a rare complication of babesiosis that can manifest even in young, immunocompetent individuals. Prompt recognition and antimicrobial treatment with close monitoring are the mainstays of therapy in hospitalized patients.