Novel real-time PCR assays for genomic group identification of tick-borne relapsing fever species Borrelia hermsii.

Modarelli JJ, et al. Diagn Microbiol Infect Dis. 2018.
Diagn Microbiol Infect Dis. 2018 Aug 8. pii: S0732-8893(18)30257-8. doi: 10.1016/j.diagmicrobio.2018.08.001. [Epub ahead of print]


Borrelia hermsii is a non-Lyme borreliosis pathogen that is responsible for causing tick-borne relapsing fever in humans and animals in the western United States. B. hermsii has been described to encompass two divergent genomic groups, GGI and GGII, which have been suggested to maintain a unique geographical distribution and potential range of pathogenicity. Though the genomic groups have been extensively documented in the literature, a real-time PCR tool for identifying these genomic groups is lacking. This study describes the development and validation of two flaB-based quantitative real-time PCR assays for differentiating between the two genomic groups of B. hermsii while also maintaining specificity against other closely related Borrelia species. The diagnostic specificity of the assays were evaluated using a large panel of various Borrelia species, including a collection of 22 B. hermsii culture isolates purified from various hosts. The high sensitivity and specificity of the assays provide a useful tool for supporting future studies aimed at evaluating the geographical distribution as well as potential intraspecies pathogenicity within arthropod vectors and mammalian hosts.



While the study outcome was to determine geographical distribution and potential intraspecies pathogenicity, I for one would like to see a switch in thinking to less concern for geography and more concern for accurate testing for patient diagnosis.  The geographical emphasis has worked against patients for over 40 years and according to everything coming across this desk, I think we need to embrace this pandemic for what it is – a pandemic that knows no borders.

The sooner we quit looking at maps the sooner patients are going to be believed, validated, and actually helped.

Go here for more on Tick-relapsing fever:  Please notice Dr. Cameron’s comment about another relapsing fever caused by Bm:  “You might assume a patient infected with Borrelia miyamotoi, a relapsing fever spirochete, to present with a relapsing fever. However, your assumption would be wrong 48 out of 50 times, according to a case series published in the Annals of Internal Medicine. [1] The authors found that only 2 out of 50 patients infected with the relapsing spirochete B. miyamotoi actually presented with a relapsing fever. [1]….The individuals exhibited symptoms similar to those found in other tick-borne illnesses.

So while researchers are trying to separate out all the various strains and the particular geography, clinicians are struggling with the fact that although many of the strains are supposed to be “relapsing fever” they actually present clinically like other TBI’s such as Lyme and cause a clinical picture quite different from relapsing fever.  This is paramount for clinicians to understand as the patients showing up in their offices have symptoms quite different from what the researchers are stating.

Be your own advocate and learn as much as you can.  Chances are you will be educating your practitioner.