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In North America, ticks are the primary vectors of infectious diseases.(1) Worldwide, ticks rank second only to mosquitoes in disease transmission. In the United States, tick-borne diseases include Lyme disease, Rocky Mountain spotted fever, human monocytic and granulocytic ehrlichiosis, babesiosis, tularemia, relapsing fever, Borrelia miyamotoi infection, and Colorado tick fever. Several of these diseases are transmitted by the same tick, and coinfections are occasionally seen.
Symptoms of the various tick-vectored diseases range from mild to life-threatening. Early symptoms, which include fever, aches, and malaise, do not aid in distinguishing the various diseases. Because early treatment can minimize or eliminate the risk of severe disease, early detection is essential, yet patients may not have developed distinctive symptoms to help in the differential diagnosis. A tick-borne panel can assist in identifying the pathogen, allowing treatment to be initiated.
Lyme disease is best detected through 2-tiered serologic testing. Acute ehrlichiosis, anaplasmosis, and babesiosis infections are best diagnosed using molecular amplification methods that offer sensitive, specific, and rapid detection of these agents.
For information on the specific diseases, see the individual tests.
Evaluation of patients with suspected human monocytic and granulocytic ehrlichiosis, and babesiosis
Evaluation of patients with a history of, or suspected, tick exposure who are presenting with fever, myalgia, headache, nausea, and other nonspecific symptoms
A positive LBAB / Babesia species, Molecular Detection, PCR, Blood test result indicates the presence of Babesia species DNA and is consistent with active or recent infection. While positive results are highly specific indicators of disease, they should be correlated with blood smear microscopy, serological results, and clinical findings.
A negative LBAB test result indicates absence of detectable DNA from Babesia species in the specimen, but does not always rule-out ongoing babesiosis in a seropositive person, since the parasitemia may be present at a very low level or may be sporadic.
A positive EHRL / Ehrlichia/Anaplasma, Molecular Detection, PCR, Blood test result indicates the presence of specific DNA from Ehrlichia chaffeensis, Ehrlichia ewingii, Ehrlichia muris eauclairensis organism, or Anaplasma phagocytophilum, and support the diagnosis of ehrlichiosis or anaplasmosis.
A negative EHRL test result indicates the absence of detectable DNA from any of these 4 pathogens in specimens, but does not exclude the presence of these organisms or active or recent disease.
Since DNA of Ehrlichia ewingii is indistinguishable from that of Ehrlichia canis by this rapid PCR assay, a positive result for Ehrlichia ewingii/canis indicates the presence of DNA from either of these 2 organisms.
While the LBAB / Babesia species, Molecular Detection, PCR, Blood assay is designed to detect symptomatic infection with Babesia microti, Babesia duncani, and Babesia divergens/MO-1, it may detect low-grade asymptomatic parasitemia in individuals in babesiosis-endemic areas. Thus, it should only be used for testing patients with a clinical history and symptoms consistent with babesiosis.
The EHRL / Ehrlichia/Anaplasma, Molecular Detection, PCR, Blood assay should not be used for screening asymptomatic individuals, and should only be used to test patients with signs and symptoms of ehrlichiosis or anaplasmosis.
A negative result does not indicate absence of disease.
The EHRL test may detect DNA of Ehrlichia canis (reported to cause asymptomatic infection in Venezuela only).
The EHRL test does not detect DNA of Rickettsia (formerly Ehrlichia) sennetsu, which has been reported to cause a rare mononucleosis-like illness in humans (in Japan and Malaysia).
Inadequate specimen draw or improper conditions for storage or transport may invalidate test results.
Babesia species, MOLECULAR DETECTION, PCR
Ehrlichia/Anaplasma, MOLECULAR DETECTION, PCR
Diaz J: Chapter 297: Ticks (including tick paralysis). In Mandell, Doublass, and Bennett's Principles and Practice of Infectious Diseases. Vol 2. Seventh edition. Edited by GL Mandell, JE Bennett, R Dolin, Philadelphia, Churchill Livingston, 2010, pp 3649-3661