New Study Identifies Blood Transfusion As Highly Effective Treatment For Severe Babesiosis Cases

A new study suggests that a certain kind of blood transfusion could be effective in treating severe cases of babesiosis, the rare tick-borne illness also known as Nantucket Fever.

“It may be life-saving,” senior author Peter Krause told the Current. “If I were to explain the importance of this study to someone, especially at high risk, I would say you can derive a little bit of comfort from this.”

Nantucket is an epicenter for babesiosis, a parasitic disease that can cause fever, fatigue, anemia, and even death, though the absolute number of infected individuals on the island remains low.

The paper, written by a large number of scientists led by Harvard Medical School researcher David Leaf, shows that red blood cell exchange transfusion could significantly reduce death rates from the disease and be a strong treatment option for patients with severe cases.

“If you [have a severe case], you really want to get yourself to a hospital where they have the capability of performing exchange transfusion,” Leaf said.

The study looked at 3,000 patients hospitalized with babesiosis at 82 medical centers over 15 years. Of the severely ill patients who received red blood cell exchange transfusion, 3.6 percent died or were re-admitted to the hospital within 30 days. Of the patients who did not receive the treatment, 9.8 percent died or were re-admitted.

In red blood cell exchange transfusion, a patient’s blood is circulated through a machine that removes infected red blood cells and replaces them with healthy cells from donors. It’s an uncommon treatment for babesiosis, but Leaf and Krause think that their paper may change that, though the use will likely stay confined to the most critical patients, given how invasive the procedure can be.

Nantucket physician and tick expert Dr. Tim Lepore said he previously treated a patient with babesiosis who ultimately received such a transfusion at a Boston hospital, and that such treatments are reserved for the worst cases of the tick-borne disease. The procedure, which Lepore said has been around for years, would likely only be done at a more advanced medical facility off-island, and not at Nantucket Cottage Hospital, should a patient here ever need it.

“If you're sick enough to need it (a transfusion), you're too sick to be here,” Lepore said. “Babesia can be a really benign problem, particularly in young kids who have very good immune systems - they can handle it. It's when you have somebody who's got a variety of other medical issues or is immunosuppressed, then they might end up with something. But, I mean, that's been around a while.”

Because babesiosis is a rare disease, with only a little over 2,000 documented cases in the United States each year, research is often severely underfunded, even though the number of documented cases likely dramatically understates how many people actually contract babesiosis.

“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,” Leaf said. “Our study provides the first large, multicenter evidence demonstrating that ET is associated with a substantially lower risk of in-hospital death or readmission.”

Krause said that the study is essentially the largest clinical study ever done on babesiosis. The size is particularly notable given how rare the disease is and how sparse funding can be, and was only possible because dozens of doctors and scientists agreed to participate and lend data.

“This project represents a grassroots, investigator-initiated effort that brought together more than 100 collaborators across numerous hospitals and specialties, underscoring the power of large-scale, community-driven research to address important clinical questions,” Leaf said. “As cases continue to rise, improving recognition of severe babesiosis and ensuring access to effective treatments such as exchange transfusion will be critical.”

Like many tick-borne illnesses, rates of babesiosis are increasing as climate change allows tick populations to thrive and expand their range.

The paper is also notable for its statistical approach. The rarity of babesiosis and the lack of funding make a double-blind clinical trial difficult to ever achieve. Instead, Leaf opted for a “target trial emulation,” in which the circumstances of a clinical trial are essentially reverse-engineered to reduce the impact of variables that could unduly effect the results, like the age or gender of patients.