Red blood cell exchange linked to better outcomes in severe babesiosis, study finds

A new study led by researchers from the Yale School of Public Health (YSPH) and Mass General Brigham finds that a procedure called red blood cell exchange transfusion significantly improved outcomes for patients hospitalized with severe babesiosis, a potentially life-threatening disease spread by ticks.

Red blood cell exchange transfusion (ET) involves removing a patient’s infected red blood cells and replacing them with healthy red blood cells. Doctors sometimes use this treatment in the most serious cases, but its benefits have been unclear because of limited data.

This new study, published in JAMA Internal Medicine, provides strong evidence that the procedure is effective.

“Our study shows that patients with severe babesiosis who received exchange transfusion were significantly less likely to die in the hospital or be readmitted within 30 days compared with those who did not receive the treatment,” said senior author Peter J. Krause, MD, a senior research scientist at YSPH and the Yale School of Medicine. “Even though the patients who received exchange transfusion were initially more seriously ill than those not given ET, their outcomes were better. This study provides the strongest evidence to date that exchange transfusion improves outcomes in high-risk patients.”

Babesiosis is an emerging worldwide tick-borne illness caused by a parasite that infects red blood cells. It is most commonly found in the northeastern and upper Midwestern United States and is spread by the same tick that transmits Lyme disease. While many cases are mild, severe infections can lead to organ failure and death, especially in older adults and people with weakened immune systems.

Standard treatment includes antibiotics, but in more serious cases, that may not be enough.

“Reported cases of babesiosis in the United States have increased over the past several decades, yet large-scale, high-quality data to guide the treatment of severe babesiosis—including the role of exchange transfusion—remain limited,” said lead author David E. Leaf, MD, MMSc, of Harvard Medical School and Mass General Brigham. “Our study provides the first large, multicenter evidence demonstrating that ET is associated with a substantially lower risk of in-hospital death or readmission.”

The researchers analyzed data from more than 3,000 patients hospitalized with babesiosis at 82 medical centers across the northeastern United States over a 15-year period. Among 629 patients who were ill enough to be included in the analysis, about one-third received exchange transfusion within the first week of hospitalization.

The results were notable: after accounting for baseline differences in illness severity, 3.6% of patients who received the procedure died in the hospital or were readmitted within 30 days, compared to 9.8% of those who did not receive it.

“These findings give clinicians clearer guidance when treating the sickest patients,” Krause said. “For those who meet the criteria used in our study, exchange transfusion should be strongly considered. Using it more consistently could reduce complications, lower readmissions, and ultimately save lives.”

The researchers note that the study has some limitations, including differences between patients that could not be fully accounted for. More research is needed to better understand which patients benefit most, particularly those with less severe illness.

“This project brought together more than 100 collaborators across many hospitals and specialties,” said Leaf. “It shows how large-scale collaboration can help answer important clinical questions. As babesiosis continues to rise, improving diagnosis and access to effective treatments will be critical.”

Authorship: In addition to Peter Krause, MD, Yale authors include Zoe Burger, MD; Tayoot Chengsupanimit , MD; Tammy Stalmack, MHS; Rachel Aber, MD; Marjorie Golden, MD; Maria Koshy, MD; Kendall Wright, MD; Grace Cortezzo, ABA; Gavin McLeod, MD; Scott Roberts, MD

Disclosures: David E. Leaf received research support, unrelated to the current project, from BTG International, Metro International Biotech LLC, Renibus Therapeutics, Inc., Alexion Pharmaceuticals, and 60 Degrees Pharmaceuticals, Inc, and served as a consultant for MexBrain, Entrada Therapeutics, CardioRenal Systems, Inc., and Alexion Pharmaceuticals. Peter J. Krause received payments unrelated to this project from UpToDate, Inc., 60 Degrees Pharmaceuticals, Inc., and Pfizer, Inc., and serves on the American Lyme Disease Foundation Board of Directors.

Funding: Llura A. Gund Fund for Vector-Borne Disease Research and the Gordon and Llura Gund Foundation (PJK)