Babesiosis Clinical Trials and Treatments

Babesiosis is caused by Babesia parasites, most commonly Babesia microti in the United States. Like malaria, the parasites invade and destroy red blood cells, causing hemolytic anemia that ranges from mild to life-threatening. The disease is transmitted by the blacklegged tick (Ixodes scapularis), the same tick responsible for Lyme disease and anaplasmosis, which is why coinfection is common in endemic areas.

The most common symptoms of Babesiosis include High fever, chills, and drenching sweats, Fatigue and general malaise lasting weeks to months, Hemolytic anemia (destruction of red blood cells), Dark urine caused by hemoglobin breakdown, Enlarged spleen and liver, among others. Babesiosis affects approximately 3,586 US cases were reported to the CDC in 2023, up from 1,742 in 2014, with most in the Northeast and upper Midwest. Classified as rare by GARD, NORD and Orphanet. The other species are far rarer: about 14 Babesia duncani cases have been reported in the US, all in western states, and 6 Babesia divergens-like (MO-1) cases through 2018. Symptoms can range from mild to severe and may vary between individuals.

Trial Friend lists all active clinical trials for Babesiosis from ClinicalTrials.gov, with eligibility criteria translated into plain English. Patients can filter by trial phase and recruitment status, search by location, and use the Match Me tool to score trials against their profile. Babesiosis has more active clinical trials than most tick-borne coinfections. Tafenoquine, an antimalarial drug, is in a Phase 2 trial for chronic babesiosis with severe fatigue (the B-FREE study, NCT06656351, sponsored by 60 Degrees Pharmaceuticals), which ClinicalTrials.gov lists as recruiting as of October 2026.

As of October 21, 2026, no current FDA drug label names Babesiosis as a condition the drug treats.

Babesiosis is caused by Babesia parasites, most commonly Babesia microti in the United States, transmitted through the bite of the blacklegged tick (Ixodes scapularis). The parasites invade and destroy red blood cells, causing hemolytic anemia. The same tick transmits Lyme disease (Borrelia burgdorferi) and anaplasmosis (Anaplasma phagocytophilum), which is why coinfection rates of 2 to 40 percent are documented in endemic areas. The geographic range of Ixodes scapularis has expanded dramatically over the past several decades, driven by climate warming, white-tailed deer population growth, reforestation, and suburban sprawl into wooded areas. Richard Horowitz's MSIDS model, a framework from Lyme-literate medicine, lists Epstein-Barr virus and cytomegalovirus among infections that can add to chronic symptoms, though no study has shown that babesiosis itself reactivates them.

Babesiosis is not caused by a single gene mutation, so there is no diagnostic genetic test for the disease itself. However, host immune genetics significantly influence disease severity and relapse risk. Asplenia or hyposplenia (from splenectomy, sickle cell disease, or congenital conditions) is the strongest risk factor for severe babesiosis because the spleen is the primary organ for clearing parasitized red blood cells. A weakened immune system, for example from rituximab treatment or B cell lymphoma, raises the risk of severe infection and of infection that persists or relapses after standard treatment, according to a study by Krause and colleagues (2008) and the 2020 IDSA guideline. For people also infected with Lyme disease, HLA-DR4 and related HLA-DR molecules have been linked to Lyme arthritis that persists after antibiotics (Steere and colleagues, 2006), and the TLR1 1805GG variant to stronger inflammation and the same antibiotic-refractory arthritis (Strle and colleagues, 2012). Lyme-literate doctors such as Richard Horowitz test patients with chronic tick-borne illness for MTHFR gene variants and use methylation support during treatment, and in his 2018 review of 200 patients with chronic Lyme disease, 52.5% carried an MTHFR variant. No controlled study has yet tested whether these variants change how people with babesiosis respond to treatment. Patients with known immunodeficiency conditions should discuss heightened surveillance with their physician before traveling to tick-endemic regions.

Eligibility for Babesiosis clinical trials depends on factors like age, diagnosis, treatment history, and overall health. Each trial sets its own inclusion and exclusion criteria. Trial Friend translates these requirements from medical language into plain English so patients can review them more easily. The Match Me tool can score your profile against active trials to help identify studies that may be a fit.

Participating in a Babesiosis clinical trial typically involves scheduled visits, medical tests, and close monitoring by a research team. Depending on the study phase, you may receive an investigational treatment, a placebo, or the current standard of care. Trials may last from a few weeks to several years. Study participation is voluntary, and you can withdraw at any time.

Babesiosis clinical trials may exclude patients on certain antimalarial or antiparasitic regimens that could confound study results. Standard treatment (atovaquone plus azithromycin, with clindamycin plus quinine as the alternative) is typically the baseline these trials aim to improve upon. If you are on immunosuppressive therapy such as rituximab or TNF inhibitors, this affects both disease severity and trial eligibility. Trial Friend's medication conflict checker scans each trial's exclusion criteria against common babesiosis and coinfection medications including atovaquone, azithromycin, clindamycin, quinine, doxycycline (for Lyme or anaplasmosis coinfection), and immunosuppressive agents. The checker flags the specific drug, exclusion language, and a confidence level so you can discuss timing with your Lyme-literate doctor or infectious disease specialist.

Key questions to ask your Lyme-literate doctor (LLMD) or infectious disease specialist about babesiosis clinical trials include: Has my infection been confirmed by blood smear showing Babesia ring forms and PCR, not just antibody testing? Have I been tested for Lyme and Anaplasma coinfection, since all three share the same tick vector? If standard atovaquone-azithromycin has not cleared my infection or my symptoms, would the B-FREE tafenoquine trial at Mount Sinai or the tafenoquine expanded access program, both from 60 Degrees Pharmaceuticals, fit me? Is my spleen functioning normally, and could hyposplenia explain relapsing parasitemia? Some Lyme-literate doctors check for MTHFR variants and for Epstein-Barr virus or cytomegalovirus, so would either test help in my case, and what evidence is there for it? Has parasite resistance been considered as a cause of relapse, since cytochrome B variants in Babesia microti are linked to treatment failure?