2589. Two Cases of Congenital Babesiosis

BACKGROUND: Babesiosis is caused by Babesia microti and often transmitted via Ixodes scapularis. To the best of our knowledge, only 9 cases of vertical transmission have been reported. The spectrum of clinical presentation and optimal therapy for this population remains unknown. METHODS: Case 1 is a 4 week old female admitted with fever and irritability for 2 days. She was pancytopenic, with Hgb of 9.2 g/dL, Plt of 57 K/mm(3), and absolute neutrophil count (ANC) of 500/mm(3). Thin smear revealed 2.5% parasitemia. Mother was diagnosed with acute Lyme disease in the seventh month of pregnancy. Maternal serologies were positive for B. microti (IgM 1:100 and IgG >1:320). The infant received 1 PRBC transfusion and was treated with 10 days of atovoquone and azithromycin. Case 2 is a 5 week old female twin A admitted with 2 days of pallor, fatigue and poor feeding. Initial Hgb was 3.4 Gm/dL. Peripheral blood smear revealed many intraerythrocytic parasites consistent with B. microti. Thin smear obtained 24 hours after initiation of therapy showed 2% parasitemia. During hospitalization, the patient developed neutropenia with ANC nadir of 800/mm(3). The patient required 4 PRBC transfusions and was treated with azithromycin and atovoquone for 10 days. The mother had an acute, self-limited febrile illness at 23 weeks gestation. At infant’s presentation, maternal serologies revealed negative B. microti IgM and positive IgG (1:160). Placental tissue from both twins was positive for B. microti DNA by PCR. Twin B was asymptomatic, had negative B. microti blood PCR, a negative B. microti IgM, positive IgG of 1:30 felt to represent transplacental maternal antibody, and did not require treatment. RESULTS: Both infants were successfully treated without relapse. CONCLUSION: Congenital babesiosis is rare and may cause profound hematologic disturbances. We report 2 cases exhibiting neutropenia in addition to anemia and thrombocytopenia, supporting recent assertions by Wormser et al. that this is a common finding. In addition, Case 2 presented with a severe hemolytic anemia significantly worse than previously reported. Finally, we demonstrated successful treatment in neonates without exchange transfusion, even with severe anemia. DISCLOSURES: All authors: No reported disclosures.