A recent study by Quest Diagnostics and the University of North Carolina at Chapel Hill has found that nearly one in three patients with suspected Lyme disease also had antibodies against one or more additional tick-borne pathogens. 

Published in JAMA Network Open, the study, titled "Coseropositivity to Tick-Borne Pathogens Among Patients Suspected to Have Lyme Disease," analyzed de-identified test results from 193,260 individuals across the United States who underwent testing for tick-borne diseases between January 2021 and December 2025. The study is believed to be the largest serology-based, simultaneous evaluation of multiple tick-borne pathogens in the U.S. and the largest involving a dataset as recent as 2025. 

Key findings: 

• 29.5% of individuals who had antibodies against Borrelia burgdorferi, the bacterium that causes Lyme disease, also had antibodies against at least one other tick-borne pathogen. 

• Only 5.5% of those without antibodies for Lyme disease had antibodies against another tick-borne pathogen.  

• The most frequent pattern of co-seropositivity was observed among other pathogens transmitted by the blacklegged tick, the primary vector of Borrelia burgdorferi, including Babesia microti and Anaplasma phagocytophilum. 

• Among the entire cohort, 5% of individuals were seropositive for B. burgdorferi; 3.4% for Babesia microti (a malaria-like parasite); 3.1% for Anaplasma phagocytophilum; and 1.0% for Ehrlichia species. 

• Patients in the Northeastern U.S. were roughly twice as likely to have antibodies co-detected against non-Lyme disease pathogens (31.1% of patients who were seropositive for B. burgdorferi) than other parts of the U.S. [Midwest (16.6%); South (16.0%); West (13.6%)] 

• Babesia antibodies were most commonly co-detected among patients who were seropositive for B. burgdorferi, reaching 18.5% in the Northeast. 

More than 40% of all the diagnostic panel testing occurred during the summer months of June through August and nearly 26% in the fall months of September through November, reflecting the seasonal nature of tick activity. Additionally, the cohort was primarily represented by the Northeast (70.6% of all patients tested) but also included other regions, reflecting the known habitat of ticks that transmit these diseases. 

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