Quest Diagnostics Finds High Tick-Borne Disease Co-Exposure

Secaucus, New Jersey, U.S., September 21, 2026

Quest Diagnostics Study Reveals Co-Seropositivity

The large retrospective analysis evaluated serological evidence for multiple tick-borne pathogens, providing researchers with an opportunity to examine co-seropositivity patterns across different U.S. regions. Among the entire study population, 5.0% were seropositive for B. burgdorferi, while 3.4% had antibodies against Babesia microti, 3.1% against Anaplasma phagocytophilum, and 1.0% against Ehrlichia species. Among individuals with evidence of Lyme exposure, the most frequent co-detected pathogens included Babesia and Anaplasma, which can be transmitted by the same blacklegged tick responsible for transmitting B. burgdorferi. Co-exposure may occur when a single tick carries multiple pathogens or when an individual experiences multiple tick bites.

The geographic analysis also identified notable regional differences. In the Northeastern United States, 31.1% of patients who were seropositive for B. burgdorferi also had antibodies against non-Lyme pathogens. The corresponding figures were 16.6% in the Midwest, 16.0% in the South and 13.6% in the West. Babesia antibodies were particularly prominent in the Northeast, where they were detected in 18.5% of patients who were seropositive for B. burgdorferi. The researchers said the results provide a detailed picture of potential tick-borne co-exposure across a geographically diverse U.S. population.

Findings Highlight Comprehensive Tick-Borne Testing

The study has implications for infectious disease diagnostics, particularly because Lyme disease, anaplasmosis and babesiosis can present with overlapping symptoms. Quest Diagnostics noted that relying on testing for only one pathogen may potentially miss evidence of another tick-borne infection. This distinction can be clinically important because different pathogens may require different therapeutic approaches. For example, standard Lyme disease treatments such as doxycycline, amoxicillin or cefuroxime axetil do not treat Babesia, which requires a different antimicrobial regimen when active babesiosis is present. The researchers also identified strong seasonal testing patterns. More than 40% of diagnostic panel testing occurred during June through August, while nearly 26% occurred during September through November, consistent with the seasonal nature of tick activity. The Northeast accounted for 70.6% of the testing cohort, although the analysis included patients from other U.S. regions as well.

Study Supports Broader Tick-Borne Disease Research

The scale of the dataset makes the study significant for the evolving field of tick-borne disease diagnostics. The research provides real-world laboratory evidence that multiple pathogen exposures can occur among patients being evaluated for Lyme disease and offers regional information that could support further investigation into diagnostic patterns. However, the researchers emphasized an important limitation: the analysis was based on serological data without accompanying clinical information. Antibodies can remain detectable after previous exposure, meaning co-seropositivity does not by itself establish an active concurrent infection. The findings therefore demonstrate patterns of antibody detection rather than confirming that every co-positive patient had active coinfection.

For cGxP.wire readers, the study highlights the growing importance of comprehensive diagnostic testing, infectious disease surveillance and laboratory medicine as researchers work to understand the increasingly complex landscape of tick-borne diseases. The findings from Quest Diagnostics and UNC Chapel Hill add large-scale evidence to research on Lyme disease, babesiosis, anaplasmosis and pathogen co-exposure, while underscoring the need to interpret serological findings alongside clinical information and other diagnostic evidence.

Source: Quest Diagnostics press release