Meningoencephalitis from Borrelia miyamotoi in an immunocompromised patient

Abstract

Ixodes ticks serve as vectors for Borrelia burgdorferi, the agent of Lyme disease. Globally, these ticks often concurrently harbor B. miyamotoi, a spirochete that is classified within the relapsing-fever group of spirochetes. Although humans presumably are exposed to B. miyamotoi, there are limited data suggesting disease attributable to it. We report a case of progressive mental deterioration in an older, immunocompromised patient, and even though Koch's postulates were not met, we posit B. miyamotoi as the cause, owing to its direct detection in cerebrospinal fluid (CSF) with the use of microscopy and a polymerase-chain-reaction (PCR) assay. It is likely that B. miyamotoi is an underrecognized cause of disease, especially in sites where Lyme disease is endemic.

Figure 1. Morphologic Features of Spirochetes Detected in Cerebrospinal Fluid

Panels A and B show the spirochetes as viewed with the use of dark-field microscopy. Panels C and D show the spirochetes as viewed with the use of bright-field microscopy, with Giemsa staining and a pH of 7.0. The bar indicates 2 µm.

Figure 2. Phylogenetic Analysis of DNA Sequences Obtained by Polymerase-Chain-Reaction Amplification of the Patient’s Cerebrospinal Fluid

The maximum-likelihood algorithm was implemented in the MEGA 5.05 program. The branch labels are from GenBank, which includes accessions deposited with data stating that the sequences came from Ixodes dammini and others stating that they came from I. scapularis. Panel A shows the 16S ribosomal RNA gene target, with the use of a 1127-base-pair portion and the Hasegawa–Kishino–Yano with invariant sites (HKY+G+I) plus gamma model. Panel B shows the flagellin gene target, with the use of a 456-base-pair portion and the Tamura 2 parameter (T92) model. The arrow marks the spirochete in the sample from our patient. The scale bars denote the genetic distance in nucleotide substitutions per site.