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| __NOTOC__
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| {{Relapsing fever}}
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| {{CMG}}
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| ==Overview==
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| ==Laboratory Findings==
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| [[Image:Borrelia spirochetes.jpg|right|thumb|Borrelia spirochetes]]
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| [[Image:Peripheral blood smear from Schwan, Policastro et al.jpg|right|thumb|Peripheral blood smear from Schwan, Policastro et al 2003]]
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| *The definitive diagnosis of TBRF is based on the observation of Borrelia spirochetes in smears of peripheral [[blood]], [[bone marrow]], or [[cerebrospinal fluid]] in a symptomatic person. Although best visualized by dark field microscopy, the organisms can also be detected by Wright-Giemsa or acridine orange-stained preparations.
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| *The organisms are best detected in blood obtained while a person is [[febrile]]. With subsequent febrile episodes, the number of circulating spirochetes decreases, making it harder to detect spirochetes on a peripheral blood smear. Even during the initial episode spirochetes will only be seen 70% of the time.
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| Blood samples obtained before [[antibiotic]] treatment can be cultured using BSK medium or by inoculating immature mice. The spirochete will usually be evident within 24 hours if the blood was drawn during a febrile episode.
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| Although not valuable for making an immediate diagnosis, serologic testing is available through public health laboratories and some private laboratories. Acute serum should be taken within 7 days of symptom onset and convalescent serum should be taken at least 21 days after symptoms start. Early [[antibiotic]] treatment may blunt the [[antibody]] response and the antibody levels may wane quickly during the months after exposure. To confirm the diagnosis of TBRF, Borrelia specific antibody titers should be increased between acute and convalescent serum samples and convalescent serum antibody levels should be at least two standard deviations above pooled negative controls. Serologic testing for TBRF is not standardized and results may vary by lab. Patients with TBRF may have false-positive tests for Lyme disease because of the similarity of proteins between the two organisms.
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| Incidental laboratory findings include normal to increased white blood cell count with a left shift towards immature cells, a mildly increased serum [[bilirubin]] level, mild to moderate [[thrombocytopenia]] (low platelet count), elevated [[ESR]] and slightly prolonged coagulation tests, [[PT]] and [[APTT]].
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| ==References==
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| {{Reflist|2}}
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| [[Category:Bacterial diseases]]
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| [[Category:Zoonoses]]
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| [[Category:Infectious diseases]]
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