[2] Endemic foci for B. turicatae occur in Texas and Florida, where clinical isolates have been obtained from sick dogs, suggesting a role for wild canids in the maintenance of the spirochaetes in nature.
[2] Currently, the only known isolates of B. turicatae originate from argasid soft ticks and sick dogs, although the mammalian hosts for most species of relapsing fever spirochaetes include rodents and insectivores.
[5] The clinical features of relapsing fever may include recurring febrile episodes, chills, nausea, headache, muscle and joint aches, vomiting, lethargy, thrombocytopenia, spirochetemia, anemia, facial paralysis, neutrophilia, lymphopenia, anorexia, dry cough, light sensitivity, rash, neck pain, eye pain, confusion, dizziness, eosinopenia, myocarditis, dermatitis, brain infection, lymphoid hyperplasia, and pregnancy complications.
[5] During the "chill phase" of the crisis, which lasts 10 to 30 minutes, patients develop very high fever (up to 106.7 °F or 41.5 °C) and may become delirious, agitated, tachycardic, and tachypneic.
[5] The definitive diagnosis of TBRF is based on the observation of Borrelia spirochaetes in smears of peripheral blood, bone marrow, or cerebrospinal fluid in a symptomatic person.
[5] With subsequent febrile episodes, the number of circulating spirochaetes decreases, making detecting spirochetes on a peripheral blood smear more difficult.
[2][6] However, the ecology, pathogenesis, and distribution of B. turicatae remains understudied, and regions of endemicity not previously known to exist continue to be identified.
[2] As antibody responses generated against recombinant BipA appear to be unique to infections caused by B. turicatae, these immune responses generated against BipA suggest that it may be a species-specific antigen that could be used to identify additional vertebrate hosts, define endemic foci for B. turicatae, and increase the awareness of the disease to improve healthcare.
[5] Although the CDC has not yet developed specific treatment guidelines for TBRF, experts generally recommend tetracycline 500 mg every 6 hours for 10 days as the preferred oral regimen for adults.
[5] All patients treated with antibiotics should be observed during the first 4 hours of treatment for a Jarisch-Herxheimer reaction, which is a worsening of symptoms characterized by rigors, hypotension, and high fever.
[3][4] B. turicatae has two antigenically distinct isogenic serotypes, Bt1 and Bt2, which differ only in their expressed Vsps, thus in their degree of virulence and tropism, or the location of the infection.
[10] Additionally, Bt2 causes more severe systemic disease than Bt1, including conjunctivitis, ruffled skin, tibiotarsal arthritis, reduced spontaneous activity, and neonatal mortality.
[10] Relapsing fever spirochaetes have a unique process of DNA rearrangement that allows them to periodically change the expression of the VMPs in their outer membrane, which results in the generation of multiple serotypes.
[3][5] This process, called antigenic variation, allows the spirochaete to evade the host's immune response and cause relapsing episodes of fever and other symptoms.
[10] The vector, Ornithodoros turicata, is an extremely fast feeder among ticks, requiring a 5- to 60-minute blood meal, and is not likely to be collected from the host, making it difficult to track transmission.