Background: Babesiosis is an increasingly recognized parasitic infection with manifestations that range from a subclinical or mild flu-like illness to life-threatening disease. Risk factors that may be associated with a more severe clinical course include immunosuppression, splenectomy, and advanced age. The most effective chemotherapeutic regimen, clindamycin plus quinine, is sometimes ineffective in cases of severe disease.
Case report: A previously healthy, 58-year-old man was infected by Babesia microti, presumably through a tick bite. He developed fulminant disease characterized by severe hemolytic anemia, disseminated intravascular coagulation, acute renal failure, and respiratory failure. There was no history of splenectomy or immunodeficiency. He was given oral clindamycin (300 mg/4x/day) 2 days before admission. Oral quinine (650 mg/3x/day) was added upon hospitalization. There was no clinical improvement despite antibiotic therapy with clindamycin and quinine. On the second hospital day, a whole-blood exchange transfusion was performed to simultaneously lower the parasite load and replace the patient's plasma. With an automated blood cell separator, 87 percent of the patient's total blood volume was exchanged. As replacement fluid, 6.7 L of packed RBCs reconstituted with FFP (average Hct, 33%) was used. The patient's Hct increased from 26.9 percent before the exchange to 28.3 percent after the exchange. The percentage of parasitized RBCs decreased from 13.8 percent just before exchange to 4.2 percent immediately after exchange. There was rapid clinical improvement after the whole-blood exchange transfusion. The patient's subsequent clinical course was marked by a disappearance of the parasitemia and continued slow, general improvement. Therapy with clindamycin was continued for 14 days after the exchange transfusion and quinine for 17 days.
Conclusion: In cases of severe babesiosis, prompt institution of whole-blood exchange transfusion, in combination with appropriate antimicrobial therapy, can be life-saving.