The Medical clinics of North America
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Laboratory testing for B. burgdorferi infection is intended to substantiate a physician's clinical judgment of whether a patient has Lyme disease or not. Cultivation of B. burgdorferi from a patient's skin or blood is the gold standard for demonstration of active infection, but it is expensive and lacks clinical sensitivity. Detection of spirochetal DNA in clinical samples by PCR has better sensitivity, but PCR for B. burgdorferi has not yet been standardized for more routine diagnostic testing. ⋯ This estimate can serve to reassure patients who are at low risk of B. burgdorferi infection but are seeking a Lyme test for complaints of a more nonspecific nature. Although new subunit serologic assays based on recombinant proteins are becoming available commercially, the longstanding two-test approach, in which a positive or indeterminate result with a standardized, sensitive ELISA test is followed by verification with a more specific Western blot assay, still provides the physician with a reasonably accurate and reliable assessment of the presence of antibodies to B. burgdorferi. More recent challenges for serologic testing are seropositivity in the population as the result of immunization with the Lyme disease vaccine and the emergence of new Borrelia species that cause Lyme disease-like illnesses.
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Babesiosis is an emerging infection caused by protozoal parasites and transmitted by the same tick that transmits Lyme disease. Babesiosis is found throughout the world, but most cases have been described from the northeastern and northern midwestern United States. ⋯ Specific diagnosis is made through examination of a Giemsa-stained thin blood smear, DNA amplification using polymerase chain reaction, or detection of specific antibody. Treatment consists of clindamycin and quinine or atovaquone and azithromycin and, in severe cases, exchange transfusion.