Case Report: A Retrospective Serological Analysis Indicating Human Exposure to Tick-Borne Relapsing Fever Spirochetes in Texas

Abstract

In June 2013, a Caucasian male from Kerr county, Texas, with an extensive history of outdoor activity working with sheep, goats, and exotic game became ill, displaying fever, chills, uveitis, headache, retrobulbar pain, severe malaise, and weakness. Myalgia was centered on upper extremities, most notably the shoulders, arms, and hands, and by July 2013 the patient had experienced two febrile episodes (39C). Numerous insect bites were reported, most notably on areas of the body that were in direct contact with the ground, but offending arthropods were not found. The patient was initially tested for Coxiella burnetti exposure, but repeated serological results demonstrated that phase I and phase II immunoglobulin G (IgG) antibody titers failed to increase. Antibiotic treatment was administered, and symptoms improved. A retrospective evaluation of the patient's history and clinical summary led to suspicion of tick-borne relapsing fever borreliosis. The patient did not have a history of traveling outside of Texas prior to the onset of symptoms, and Borrelia turicatae was suspected as the causative agent. A serum sample was sent to us four months after antibiotic treatment, and we implemented a molecular approach to determine seroreactivity against two diagnostic antigens for relapsing fever spirochetes, recombinant glycerophosphodiester phosphodiesterase (rGlpQ) and Borrelia immunogenic protein A (rBipA).