We detected the DNA of an Anaplasma bovis-like bacterium in blood specimens from 4 patients from the United States with suspected tickborne illnesses. Initial molecular characterization of this novel agent reveals identity to A. bovis-like bacteria detected in Dermacentor variabilis ticks collected from multiple US states.

Tickborne diseases, due to a diversity of bacterial pathogens, represent a significant and increasing public health threat throughout the northern hemisphere. A high-throughput 16S V1-V2 rDNA-based metagenomics assay was developed and evaluated using >13,000 residual samples from patients suspected of tickborne illness and >1000 controls. Taxonomic predictions for tickborne bacteria were exceptionally accurate, as independently validated by secondary testing. Overall, 881 specimens were positive for bacterial tickborne agents. Twelve tickborne bacterial species were detected, including two novel pathogens, representing a 100% increase in the number of tickborne bacteria identified compared to what was possible by initial PCR testing. In three blood specimens, two tickborne bacteria were simultaneously detected. Seven bacteria, not known to be tick-transmitted, were also confirmed unique to samples from persons suspected of tickborne illness. These results indicate 16S V1-V2 metagenomics can greatly simplify diagnosis and accelerate discovery of bacterial tickborne pathogens.

Background: Tick-transmitted Borrelia species fall into two heterogeneous bacterial complexes comprised of multiple species, the relapsing fever (RF) group and the Borrelia burgdorferi sensu lato group, which are the causative agents of Lyme borreliosis (LB), the most common tickborne disease in the northern hemisphere. Geographic expansion of human LB in the United States and discovery of emerging Borrelia pathogens underscores the importance of surveillance for disease causing Borrelia. Methods: De-identified clinical specimens, submitted by providers throughout the United States, for patients suspected of LB, anaplasmosis, ehrlichiosis, or babesiosis, were screened using a Borrelia genus level TaqMan PCR. Borrelia species and sequence types (STs) were characterized by multi-locus sequence typing (MLST) utilizing next generation sequencing. Results: Among the 7,292 tested specimens tested, five different Borrelia species were identified: two causing LB, B. burgdorferi (n=25) and B. mayonii (n=9), and three RF borreliae, B. hermsii (n=1), B. miyamotoi (n=8), and CandidatusB. johnsonii (n=1), a species previously detected only in the bat tick, Carios kelleyi. ST diversity was greatest for B. burgdorferi positive specimens, with new STs identified primarily among synovial fluids. Conclusion: These results demonstrate broad PCR screening followed by MLST is a powerful surveillance tool for uncovering the spectrum of Borrelia species causing human disease, improving understanding of their geographic distribution, and investigating the correlation between B. burgdorferi STs and joint involvement. Detection of CandidatusB. johnsonii in a patient with suspected tickborne disease suggests this species may be a previously undetected cause of illness in humans with exposure to bat ticks.