https://www.ncbi.nlm.nih.gov/pubmed/30489694

2018 Nov 29:e12987. doi: 10.1111/cmi.12987. [Epub ahead of print]

The relapsing fever spirochete Borrelia turicatae persists in the highly oxidative environment of its soft-bodied tick vector.

Abstract

The relapsing fever spirochete Borrelia turicatae possesses a complex life cycle in its soft-bodied tick vector, Ornithodoros turicata. Spirochetes enter the tick midgut during a bloodmeal, and during the following weeks spirochetes disseminate throughout O. turicata. A population persists in the salivary glands allowing for rapid transmission to mammalian hosts during tick feeding. Little is known about the physiological environment within the salivary glands acini in which B. turicatae persists. In this study, we examined the salivary gland transcriptome of O. turicata ticks and detected the expression of fifty-seven genes involved in oxidant metabolism or antioxidant defenses. We confirmed the expression of five of the most highly expressed genes including glutathione peroxidase (gpx), thioredoxin peroxidase (tpx), manganese superoxide dismutase (sod-1), copper-zinc superoxide dismutase (sod-2), and catalase (cat) by reverse-transcriptase droplet digital PCR (RT-ddPCR). We also found distinct differences in the expression of these genes when comparing the salivary glands and midguts of unfed O. turicata ticks.

Our results indicate that the salivary glands of unfed O. turicata nymphs are a highly oxidative environment where reactive oxygen species (ROS) predominate, while midgut tissues comprise a primarily nitrosative environment where nitric oxide synthase is highly expressed. Additionally, B. turicatae was found to be hyperresistant to ROS compared to the Lyme disease spirochete B. burgdorferi, suggesting that it is uniquely adapted to the highly oxidative environment of O. turicata salivary gland acini.

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**Comment**

Much can be learned about Borrelia turicatae by reading this case study:  https://wwwnc.cdc.gov/eid/article/23/5/16-2069_article

We learn:

  • Ornithodoros turicata soft bodied ticks, are endemic to Texas and Florida
  • They are found in caves and ground squirrel or prairie dog burrows  https://madisonarealymesupportgroup.com/2018/04/23/tick-borne-relapsing-fever-found-in-austin-texas-caves/
  • Once infected, they remain infected for the rest of their lives, which can be up to ten years.
  • Attachment is painless
  • They are rapid night feeders (5-60min)
  • Due to their rapid feeding they are rarely found or leave lesions
  • Patient in study suffered with headache, nausea, & pain behind knees
  • Had numerous lesions which resolved after 6 days (without treatment)
  • Developed persistent fever
  • Developed thrombocytopenia (low platelets)
  • Developed elevated Erythrocyte sedimentation rate & C-reactive protein
  • Improved rapidly with doxycycline
  • Platelet count normalized within 2 weeks
  • Asymptomatic soldiers with similar exposure were treated prophylactically
  • TBRF is a neglected and probably underdiagnosed disease
  • Published cases in Texas have been supported by serology for the TBRF group, exposure location, and tick collections, but the authors state successful identification of B. turicatae in a human has not been reported
  • Military training groups in Israel have declared certain caves off limits because of heavy tick presence https://madisonarealymesupportgroup.com/2017/10/27/israeli-kids-get-lyme-disease-from-ticks-in-caves/ and have prophylactically administered doxycycline to those suspected to have been exposed
  • Asymptomatic patients given doxy don’t have a Jarisch-Herxheimer reaction but those with active illness do
Another study demonstrating the wily and adaptable nature of spirochetes.