Date of Award

Fall 2019

Document Type

Open Access Thesis


Epidemiology and Biostatistics

First Advisor

Melissa Nolan


Tick – borne relapsing fever (TBRF) is globally dispersed, and within the United States is found primarily in the mid – west, south - west, and north – west portions of the country. TBRF is a disease which causes patients to experience flu – like symptoms and is distinguished by multiple relapses of high fever which can cause individuals to be hospitalized multiple times over months. TBRF is caused by Borrelia spp. spirochetes and spread by Onthidoros spp. soft – shelled ticks. First diagnosed in the early 20th century, the disease has gone underdiagnosed and has attracted little attention for over a century despite being the cause of illness in multiple outbreaks. Previous reviews on the subject have been limited in scope and focused on state – specific reports in localized regions of the country. The primary and secondary objectives of our review were to describe the epidemiology, scope, and clinical outcomes of TBRF to update the medical community on its impact and also to establish an evidence - based reasoning for inclusion of TBRF in the NNDSS. We present our review of TBRF as the most expansive in regard to years covered and sample size. As well, this is the only review, to our knowledge, which has collected and analyzed data by infection type. Papers selected for review had to be original case reports of TBRF infections, published in English, and have occurred in the United States. Data from similar reviews were not included nor were those papers used for analysis. Added criteria were used to collect data on cases which could be used for logistic and Poisson regressions analyzing the likelihood of clinical outcomes. After the review process was complete, 80 papers were used for the primary analysis and 40 papers used to collect data for regression analyses. Results showed that most of TBRF infections took place in adults and children. Men were statistically more likely to be infected than women (p= B. turicatae infections compared to B. hermsii infections, indicating that infection type influences clinical presentation of the disease. Modeling febrile episodes and Jarisch – Herxheimer reactions on treatment type hinted that some treatments are better than others but no statistically significant claims can be drawn from this analysis. In conclusion, this review highlights important differences between our results and prior published literature reviews, as well as provides recommendations on reporting practices, treatment protocols, and future work while arguing that TBRF should be a nationally notifiable disease and reported to the NNDSS.


© 2019, Kyle M. Hatcher

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