Benefits of RBC Exchange to Treat Babesiosis

Purpose of the Study Highlighting the Potential Benefits of RBC Exchange to Treat Babesiosis

Researchers at Mass General Brigham and Yale School of Public Health have published the findings of a study in JAMA Internal Medicine that, “reveals that red blood cell (RBC) exchange transfusion (ET) may provide critical benefits for patients hospitalized with severe babesiosis.” The authors of the paper sought to, “assess the association between ET and key clinical outcomes, including in-hospital mortality.” In this context, the purpose of their research was to investigate the benefits of RBC exchange and its direct impact on Babesiosis outcomes. The study’s primary end point was, “a composite of in-hospital death during the index admission or readmission within 30 days following discharge from the index admission.” It enrolled patients between 2010 and 2024 with, “a total of 629 unique patients [eligible] for inclusion in at least one target trial emulation (TTE). Of these, ET was initiated during the first seven days of hospitalization in 209 patients (33.2 percent; median [IQR] age, 70 [61-78] years; 53 female [25.4 percent] and 156 male [74.6 percent] individuals); and not initiated in 420 patients (26.8 percent; median [IQR] age, 71 [63-80] years; 130 female [31.0 percent] and 290 male [69.0 percent] individuals).”

Findings Regarding the Potential Benefits of RBC Exchange to Treat Babesiosis

The researchers found that, “[p]atients treated with ET had a larger relative decrease in parasitemia one day after treatment assignment compared to patients not treated with ET (mean [SEM], −59.7 percent [7.3] vs −29.1 percent [2.4], respectively; P < .001), as well as larger absolute decreases in parasitemia over seven days. ET-treated patients also had higher longitudinal hemoglobin concentrations and lower LDH values and SOFA scores. In the main analysis, the primary end point occurred in 3.6 percent of patients who received ET and in 9.8 percent of those who did not (adjusted odds ratio, 0.22 [95 percent CI, 0.09-0.51].”

Conclusion

The author concluded that, “randomized clinical trials of ET for babesiosis are unlikely to be feasible given the large number of sites and long duration of time that would be required to complete enrollment, as well as potential concerns regarding clinical equipoise and inevitable crossover. Accordingly, granular multicenter data, combined with the sequential TTE approach used in this study, likely provide the best available evidence to inform current practice for the management of severe babesiosis.” These findings underscore ongoing research and support the consideration of RBC exchange in future Babesiosis treatment recommendations. Acknowledged limitations of their research included: “although we adjusted for a comprehensive set of covariates and used a rigorous TTE approach, residual confounding cannot be excluded; 30-day readmissions accounted for most of the events contributing to the composite end point; because few patients with parasitemia of less than 5 percent received ET, we could not assess its effectiveness in this subgroup; [and] we only included patients treated at hospitals in the northeastern U.S.; however, more than 90 percent of babesiosis cases in the US are reported from the Northeast.”

Citation: Leaf, D.E., Monson, A.E., Sias, J.-A., et al. “Red Blood Cell Exchange Transfusion for Severe Babesiosis.” JAMA Internal Medicine. 2026