https://www.ncbi.nlm.nih.gov/m/pubmed/29954419/

Multilocus sequence typing of clinical Borreliella afzelii strains: population structure and differential ability to disseminate in humans.

Gallais F, et al. Parasit Vectors. 2018.

Abstract

BACKGROUND: Lyme borreliosis in humans results in a range of clinical manifestations, thought to be partly due to differences in the pathogenicity of the infecting strain. This study compared European human clinical strains of Borreliella afzelii (previously named Borrelia afzelii) using multilocus sequence typing (MLST) to determine their spatial distribution across Europe and to establish whether there are associations between B. afzelii genotypes and specific clinical manifestations of Lyme borreliosis. For this purpose, typing was performed on 63 strains, and data on a further 245 strains were accessed from the literature.

RESULTS: All 308 strains were categorized into 149 sequence types (STs), 27 of which are described here for the first time. Phylogenetic and goeBURST analyses showed short evolutionary distances between strains. Although the main STs differed among the countries with the largest number of strains of interest (Germany, the Netherlands, France and Slovenia), the B. afzelii clinical strains were less genetically structured than those previously observed in the European tick population.

Two STs were found significantly more frequently in strains associated with clinical manifestations involving erythema migrans, whereas

another ST was found significantly more frequently in strains associated with disseminated manifestations, especially neuroborreliosis.

CONCLUSIONS: The MLST profiles showed low genetic differentiation between B. afzelii strains isolated from patients with Lyme borreliosis in Europe.

Also, clinical data analysis suggests the existence of lineages with differential dissemination properties in humans.

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**Comment**

This research highlights why thousands of patients remain undiagnosed. CDC two-tiered testing tests for ONE STRAIN of borrelia.  ONE.  There are 300 strains and counting worldwide.

It also shows how the differences between strains matter.  In this study, some strains were associated with the EM rash, while others were associated with disseminated symptoms – particularly neuroborreliosis.

Huh.  Guess we weren’t making it all up after all.
Could someone give the memo to the CDC, NIH, & IDSA?