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. Fewer than 3,000 reported U.S. cases per year, concentrated in the Northeast and upper Midwest. Classified as rare by GARD, NORD, and Orphanet (prevalence < 1 per 1,000,000).. 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 II trial for chronic and relapsing babesiosis (the B-FREE study at Mount Sinai, sponsored by 60 Degrees Pharmaceuticals), which ClinicalTrials.

Yes. As of September 2026, Trial Friend lists 4 FDA-approved drugs used to treat Babesiosis: Cleocin (clindamycin), first approved in 1970; Zithromax (azithromycin), first approved in 1991; Mepron (atovaquone), first approved in 1992; and Malarone (atovaquone + proguanil), first approved in 2000.

Each has its own page with what the label covers, side effects and how it is given, and the Treatments section of this page adds any further approved drugs found in FDA labeling data.

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. The immune suppression caused by babesiosis can reactivate latent Epstein-Barr virus (EBV) and cytomegalovirus (CMV), compounding the clinical picture.

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. MTHFR gene variants (C677T, A1298C) affect methylation and detoxification capacity, which can influence how patients process treatment metabolites and manage Herxheimer reactions during therapy. HLA-DR4 is associated with treatment-resistant Lyme arthritis in coinfected patients. TLR1 polymorphisms (1805GG variant) are linked to excessive inflammatory response in tick-borne disease. 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, or clindamycin plus quinine for severe cases) 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 failed, would I qualify for the tafenoquine Phase II trials (B-FREE study at Mount Sinai, or the 60 Degrees Pharmaceuticals trial)? Is my spleen functioning normally, and could hyposplenia explain relapsing parasitemia? Should we check for EBV and CMV reactivation given my immune suppression? If I have MTHFR variants, should I be on methylated B vitamins to support detoxification during treatment? Has parasite resistance been considered as a cause of relapse, since cytochrome B variants in Babesia microti are linked to treatment failure?