Heavy parasitemia in babesiosis treated without adjunctive red cell exchange.

Babesiosis is a tick-borne infectious disease caused by the protozoa Babesia but transplacental, and transfusion transmission may occur. While most infections are asymptomatic, rarely, it can present with a severe, life-threatening illness. Treatment is primarily with antibiotics, but red cell exchange (RCE) has been used in more severe cases which are characterized by high-grade parasitemia, evidence of severe hemolysis and or multi-organ failure. A threshold parasite level of 10% has arbitrarily been applied as an indication for RCE; however, this threshold is not evidence-based.