Red Cell Exchange as Adjunctive Therapy for Babesiosis: Is it Really Effective?

Human babesiosis is a parasitic disease prevalent in the Northeastern and Midwestern United States (US). Treatment with antibiotics is the standard of care but red cell exchange (RCE) has been used as an adjunctive treatment in more severe disease. Data for the efficacy of RCE in the treatment of babesiosis has been based on case reports and case series. An English language literature search was conducted for cases of babesiosis treated with RCE since 1980 and relevant laboratory and clinical outcome data were extracted. Similar data were obtained on severe cases of babesiosis referred for RCE in our hospitals in the time period 2000 to 2020. Fifty reports including forty-one individual case reports and nine case series were retrieved. There were 108 patients that underwent RCE with an overall mortality rate of 20%. Some patients had more than one RCE. The patients varied in the level of anemia and evidence of compromise of renal or pulmonary function. The pre-RCE level of parasitemia varied between 1.7% to 85% with the vast majority >10%. The post-RCE level of parasitemia varied between 1% to 10%. Since 2000, 32 patients were referred for RCE in our hospitals and RCE was performed on 23 of 32. There were more patients treated with RCE in the second decade as compared to the first decade, 19 versus 4 respectively. The overall mortality was 22% similar to the national data. Comparing the cohort treated with RCE to the 9 patients who were treated only with antibiotics, there were similar levels of parasitemia and laboratory parameters. The overall number of days needed to achieve a parasite count <1% was similar between the two cohorts and mortality for the antibiotics only cohort was 0%. More than 40 years after the first reported case of RCE in severe babesiosis it cannot be concluded that this adjunctive therapy favorably influences the clinical outcome. Since there is largely equipoise, a registry of severe patients treated with or without RCE could identify a benefit or otherwise.