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Test Catalog

Test ID: TKPNL    
Tick-Borne Panel, Molecular Detection, PCR, Blood

Useful For Suggests clinical disorders or settings where the test may be helpful

Evaluation of patients with suspected human monocytic ehrlichiosis, human granulocytic anaplasmosis, babesiosis, or Borrelia miyamotoi infection

 

Evaluation of patients with a history of, or suspected, tick exposure who are presenting with fever, myalgia, headache, nausea, and other nonspecific symptoms

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Acute Tick-Borne Disease Testing Algorithm in Special Instructions.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Ticks are the primary vectors of infectious diseases in North America, and rank second only to mosquitoes in disease transmission worldwide. In the United States, tick-borne diseases include Lyme disease, Rocky Mountain spotted fever, human monocytic ehrlichiosis, human granulocytic anaplasmosis, babesiosis, tularemia, relapsing fever, Colorado tick fever, and Borrelia miyamotoi infection.(1) Several of these diseases are transmitted by the same tick, and coinfections are occasionally seen. In particular, Ixodes species ticks are capable to transmitting the causative agents of Lyme disease (B burgdorferi and B mayonii), anaplasmosis (Anaplasma phagocytophilum), and babesiosis (Babesia species). These diseases are prevalent throughout the northeastern and upper Midwestern states and parts of the Pacific Northwest.

 

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 rapid tick-borne PCR panel can assist in identifying the pathogen, allowing treatment to be initiated.

 

While Lyme disease due to B burgdorferi is best detected through 2-tiered serologic testing, acute ehrlichiosis, anaplasmosis, babesiosis, and B miyamotoi infection are best detected using molecular amplification assays. This tick-borne panel offers sensitive, specific, and rapid detection of the agents that cause these 4 diseases.

 

For information on the specific diseases, see the individual test IDs.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Babesia species, MOLECULAR DETECTION, PCR

Negative

 

Ehrlichia/Anaplasma, MOLECULAR DETECTION, PCR

Negative

 

Borrelia miyamotoi, MOLECULAR DETECTION, PCR

Negative

Interpretation Provides information to assist in interpretation of the test results

Borrelia miyamotoi

A positive result indicates the presence of B miyamotoi DNA and is consistent with active or recent infection. While positive results are highly specific indicators of disease, they should be correlated with symptoms and clinical findings of tick-borne relapsing fever.

 

Ehrlichia/Anaplasma

Positive results indicate presence of specific DNA from Ehrlichia chaffeensis, E ewingii, E muris eauclairensis, or A phagocytophilum and support the diagnosis of ehrlichiosis or anaplasmosis.

 

Negative results indicate absence of detectable DNA from any of these 4 pathogens in specimens, but it does not exclude the presence of the organism or active or recent disease.

 

Since DNA of E ewingii is indistinguishable from that of E canis by this rapid PCR assay, a positive result for E ewingii/canis indicates the presence of DNA from either of these 2 organisms.

 

Babesia

A positive 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 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.

 

Other tests to consider in the evaluation of a patient presenting with an acute febrile illness following tick exposure include serologic tests for Lyme disease (B burgdorferi), and molecular detection (PCR) for ehrlichiosis/anaplasmosis. For patients who are past the acute stage of infection, serologic tests for these organisms should be ordered prior to PCR testing.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This panel does not detect Borrelia burgdorferi or B mayonii, the causative agents of Lyme disease in the United States. While Lyme PCR (PBORB / Lyme Disease [Borrelia burgdorferi], Molecular Detection, PCR, Blood) can be useful for detecting acute infection with B mayonii, this organism has a limited geographic distribution (upper Midwestern United States) and is therefore not included in this panel. Serology is the preferred method for detection of B burgdorferi.  

 

For more information, see the individual test IDs.

Supportive Data

Borrelia miyamotoi:

The following assay verification data supports the use of this assay for clinical testing.

 

Accuracy/Diagnostic Sensitivity and Specificity: Clinical Samples:

-62 clinical EDTA blood specimens received in the clinical laboratory for Ehrlichia/Anaplasma PCR were tested using the Borrelia miyamotoi PCR assay. Results were compared to the MDH 16S rRNA TaqMan assay.

-In addition, 2 retrospectively identified B miyamotoi-positive specimens were confirmed by the B miyamotoi PCR assay and the MDH TaqMan assay.

 

Spiking studies:

-To supplement the clinical specimens, negative whole blood and cerebrospinal fluid (CSF) specimens were spiked with genomic or plasmid DNA of B miyamotoi near the limit of detection and tested in a blinded fashion. The sensitivity of the PCR assay was 100% and the specificity with spiked specimens was 100%. The samples were extracted and tested in a blinded fashion.

 

Species Inclusivity:

-4 strains of B miyamotoi were detected by the PCR assay.

-3 other Borrelia species that cause human tick-borne relapsing fever (B hermsii, B parkeri, and B turicatae) were also are detected at a melting temperature below that of B miyamotoi. Thus, related Borrelia species may be detected and differentiated with this assay.

-16 different strains from the B burgdorferi sensu lato group were not detected with this PCR assay.

 

Analytical Sensitivity/Limit of Detection (LoD):

-The LoD is 2,800 target copies/mL of whole blood or CSF.

 

Analytical Specificity:

-No PCR signal was obtained from the extracts of 31 bacterial, viral, parasitic, and fungal isolates from similar organisms or from organisms commonly found in the specimens tested.

 

Precision:

-Interassay precision was 100% and intra-assay precision was 100%.

 

Reference Range:

-The reference range of this assay is negative. This assay is designed to detect only species of clinical significance and is to be used for patients with a clinical history and symptoms consistent with tick-borne relapsing fever. It should not be used to screen healthy patients.

 

Reportable Range:

-This is a qualitative assay, and the results are reported as negative or positive for Borrelia miyamotoi DNA.

 

Ehrlichia/Anaplasma:

The following validation data supports the use of this assay for clinical testing. 

 

Accuracy/Diagnostic Sensitivity and Specificity:

Results from this real-time PCR assay on the LightCycler (LC PCR) were compared to those generated using conventional PCR assay for A phagocytophilum on 127 unique, archived whole blood specimens (26 positive and 99 negative specimens by conventional PCR). Using the conventional PCR as the gold standard, the diagnostic sensitivity and specificity for detection of A phagocytophilum were 100%. In addition, 12 known E chaffeensis isolates and 2 E ewingii isolates (reference strains) were tested by the LC PCR and were positive. 

 

Supplemental Data (Spiking Studies): 

To supplement the above data, 30 negative whole blood samples were spiked with A phagocytophilum positive control plasmid at the LoD (10 copies/microL). The 30 spiked specimens were run in a blinded manner along with 30 negative (nonspiked) specimens; 100% of the spiked specimens were positive, and 100% of the nonspiked specimens were negative.

 

Analytical Sensitivity/LoD:

The lower LoD of this assay for each of the species in EDTA blood is as follows:

-A phagocytophilum=approximately 10 targets per microliter

-E chaffeensis=approximately 5 targets per microliter

-E muris eauclairensis- =approximately 100 targets per microliter

-E ewingii/canis=approximately 10 targets per microliter

 

Analytical Specificity:

No PCR signal was obtained from extracts of the following organisms: herpes simplex virus, Epstein-Barr virus, Staphylococcus aureus, S epidermidis, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, Bartonella henselae, B quintana, Rickettsia typhi, R rickettsii, Toxoplasma gondii, Babesia microti MN, B microti ATCC 53899, Borellia burgdorferi ATCC 51990, Ehrlichia risticii ATCC VR-986, and Anaplasma marginale. Positive results were obtained from nucleic extracts of 2 Ehrlichia canis strains (patient strain and ATCC CRL-10390 strain), with a melting temperature (Tm) of 49.5 degrees C (indistinguishable from Ehrlichia ewingii). A positive melting peak was also noted with Ehrlichia muris (ATCC VR-1411), but the Tm (55.24 degrees C) was easily distinguished from the Tm of the target organisms.

 

Precision: 

Interassay precision was 97% and intra-assay precision was 96%.

 

Reference Range: 

Fifty whole blood specimens from normal donors were tested and found to be negative for targeted or detectable Ehrlichia and Anaplasma species.

 

Reportable Range: 

This is a qualitative assay, and results are reported as either negative or positive for targeted Ehrlichia/Anaplasma species (positive for A phagocytophilum, E chaffeensis, E muris eauclairensis , or Ehrlichia ewingii).

 

Babesia:

The following validation data supports the use of this assay for clinical testing.

 

Accuracy/Diagnostic Sensitivity and Specificity:

-96 whole blood specimens were tested by this real-time PCR assay and another real-time PCR assay. Concordance was 99%.

 

Analytical Sensitivity/LoD:

The LoD established using whole organism spiked into specimen matrix (whole blood) is as follows:

-Babesia microti, ATCC PRA 99: 2,670 target copies/mL

-Babesia duncani ATCC PRA 302: 1,540 target copies/mL

-Babesia MO-1 positive patient DNA: 10,700 target copies/mL

-Babesia divergens-positive patient DNA: 5,270 target copies/mL

 

Serial 10-fold dilutions of microscopy-positive specimens were also tested in a blinded fashion using conventional thick and thin blood films and the Mayo Babesia species PCR. The PCR was able to consistently detect two 10-fold dilutions lower than using microscopy.

 

Analytical Specificity:

No cross-reactivity was noted using a panel of 34 bacteria, viruses, parasites, and fungi were detected by the Babesia species PCR.

                         

Precision:  

Interassay and intra-assay precision was 100% precision.

 

Reference Range:  

The reference range is negative. This was confirmed by testing 93 blood specimens from asymptomatic individuals for the presence of Babesia species by the Babesia species PCR assay. All 93 specimens were negative.

 

Reportable Range:  

This test is a qualitative assay, and results are reported as positive or negative for Babesia species (B microti, B duncani, B divergens, and B MO-1).

Clinical Reference Recommendations for in-depth reading of a clinical nature

Caulfield AJ, Pritt BS: Lyme Disease Coinfections in the United States. Clin Lab Med 2015;35(4):827-846

Special Instructions Library of PDFs including pertinent information and forms related to the test