Novel Borrelia Species Causes Lyme Disease with High Spirochetemia

tick on skin
Tick with Target rash on skin: Image Credits

In a recent paper in the Lancet Infectious Diseases, Pritt et al  have identified a new genospecies of Borrelia which is attributed to have caused several cases of Lyme disease, marked by a high degree of spirochetemia.

In their research article abstract, they state:


At the Mayo clinic, from 2003 to 2014, we tested routine clinical diagnostic specimens from patients in the USA with PCR targeting the oppA1 gene of B burgdorferi sensu lato. We identified positive specimens with an atypical PCR result (melting temperature outside of the expected range) by sequencing, microscopy, or culture. We collected Ixodes scapularis ticks from regions of suspected patient tick exposure and tested them by oppA1 PCR.


100 545 specimens were submitted by physicians for routine PCR from Jan 1, 2003 to Sept 30, 2014. From these samples, six clinical specimens (five blood, one synovial fluid) yielded an atypical oppA1PCR product, but no atypical results were detected before 2012. Five of the six patients with atypical PCR results had presented with fever, four had diffuse or focal rash, three had symptoms suggestive of neurological inclusion, and two were admitted to hospital. The sixth patient presented with knee pain and swelling. Motile spirochaetes were seen in blood samples from one patient and cultured from blood samples from two patients. Among the five blood specimens, the median oppA1 copy number was 180 times higher than that in 13 specimens that tested positive for B burgdorferi sensu stricto during the same time period. Multigene sequencing identified the spirochaete as a novel B burgdorferi sensu lato genospecies. This same genospecies was detected in ticks collected at a probable patient exposure site.


We describe a new pathogenic Borrelia burgdorferi sensu lato genospecies (candidatus Borrelia mayonii) in the upper midwestern USA, which causes Lyme borreliosis with unusually high spirochaetaemia. Clinicians should be aware of this new B burgdorferi sensu lato genospecies, its distinct clinical features, and the usefulness of oppA1 PCR for diagnosis.

Named after the discovery in the Mayo Clinic, this could be a new addition to the four known disease causing genospecies of Borrelia burgdorferi sensu lato (B afzelii, B garinii, B burgdorferi sensu stricto, and B bavariensis).

Interestingly, the fact that all the novel specimen were isolated post-2012 also indicates that this is an emerging issue. As pointed out in an accompanying commentary:

The discovery of a novel tick-borne pathogen poses new challenges to diagnostics, therapy, and public health surveillance. As our environment and settlement patterns continue to change and the global human population continues to grow, we need eff ective surveillance and intervention strategies to control tickborne diseases.


  1. Pritt BS, Mead PS, Johnson DK, Neitzel DF, Respicio-Kingry LB, Davis JP, Schiffman E, Sloan LM, Schriefer ME, Replogle AJ, Paskewitz SM, Ray JA, Bjork J, Steward CR, Deedon A, Lee X, Kingry LC, Miller TK, Feist MA, Theel ES, Patel R, Irish CL, & Petersen JM (2016). Identification of a novel pathogenic Borrelia species causing Lyme borreliosis with unusually high spirochaetaemia: a descriptive study. The Lancet. Infectious diseases PMID: 26856777
  2. Wilhelmsson P, Lindgren PE. Detection of a novel Lyme borreliosis pathogen. Lancet Infect Dis. 2016 Feb 5. pii: S1473-3099(15)00483-1. doi: 10.1016/S1473-3099(15)00483-1. [Epub ahead of print] PubMed PMID: 26856776.

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