Ehrlichia and Anaplasma

Diagnostic Tests for Ehrlichia and Anaplasma

A clinical diagnosis of Ehrlichia (HME) or Anaplasma (HGA) may be difficult because symptoms can vary greatly from patient to patient. IGeneX offers the following tests to help physicians in the accurate detection of Ehrlichia and Anaplasma.

IgG and IgM Antibody for Ehrlichia (HME and HGA) by IFA

The Ehrlichia Immunofluorescence Assays (IFAs), Anaplasma phagocytophilum (HGA) IFA and Ehrlichia chaffeensis (HME) IFA are designed to detect human IgG and IgM antibodies to HGA and HME antigens, respectively, in human serum. For diagnostic purposes, HGA and HME IFA test results should be used in conjunction with other information available to the diagnosing physician.

Principal

The Ehrlichia IFA assay is a “two-stage” sandwich assay, based upon an antigen-antibody complex formation in the following steps:

  1. Binding of anti-Ehrlichiaspecific antibodies in human serum to fixed Ehrlichia
  2. Binding of fluorescent-labeled anti-humanIgG/IgM antibodies to the human anti– Ehrlichia antibodies bound to Ehrlichia on the slide.
  3. Identifing green fluorescing Ehrlichia organisms  with a fluorescent microscope.x.

Note: For HGA IFA, A. phagocytophilum is fixed to the slide and for HME IFA, Ehrlichia chaffeensis is fixed to the slide.

Ehrlichia-and-Anaplasma-Diagnostic-Testing

Reference Range

  • HME or HGAantibody titers IgM        <20
  • HME or HGAantibody titers IgG        <40

Clinical Significance

The Ehrlichia chaffeensis (HME) IFA is used to detect antibodies to Ehrlichia chaffeensis in human serum. The Anaplasma phagocytophilum (HGA) IFA is used to detect antibodies to Anaplasma phagocytophilum in human serum. Titers rise during the first two-to-four weeks of illness and decline over the next six-to-12 months. In patients with previously high titers, the presence of only IgG titer of less than 160 may indicate a resolving infection. If the IFA result is negative but the clinical symptoms of HME or HGA infection are present, PCR testing is suggested. E. chaffeensis and A. phagocytophilum are carried by the same ticks that have also been known to cause Babesiosis, Bartonellosis and Lyme disease. Patients with positive titers should also be tested for other tick-borne diseases.

Limitations

  1. A negative HME IFA test result does not exclude the possibility of  chaffeensisinfection.
  2. A negative HGA IFA test result does not exclude the possibility of  phagocytophiluminfection.
  3. Cross-reactions can occur among theRickettsiaceae, including: Rickettsia, Ehrlichia and Anaplasma.
  4. Results should be interpreted in conjunction with other laboratory and clinical findings.

Results Interpretations >
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Ehrlichia PCR

The polymerase chain reaction (PCR)-based diagnostic assays for detection of Ehrlichia from blood are highly specific to Analplasma phagocytophilum (HGA) and Ehrlichia chaffeensis (HME) DNAs. The combination of the following three steps imparts a very high specificity and sensitivity to the test:

  • Hybridization/selection
  • Amplification of Ehrlichia-specific DNA
  • Detection of Ehrlichia-specific amplified DNA fragments

Reference Range

  • Ehrlichia chaffeensis (HME):
    • Negative,  chaffeensis-specific DNA not detected
  • Anaplasma phagocytophilum (HGA): 
    • Negative,  phagocytophilum-specific DNA not detected

Clinical Significance

The Ehrlichia chaffeensis (HME) PCR test detects E. chaffeensis ribosomal DNA (rDNA) fragments in patient samples. The A. phagocytophilum (HGA) PCR test detects A. phagocytophilum rDNA fragments in patient samples. The Ehrlichia or Anaplasma rDNA fragments are hybrid-selected by probes, followed by PCR amplification of the selected fragments using specific primers. PCR products are then confirmed with E. chaffeensis- and A. phagocytophilum-specific probes by southern blot assay.

Limitations

  1. Results should be interpreted in conjunction with other laboratory and clinical findings.
  2. Test results can only help the physician in confirming a clinical diagnosis.

Results Interpretations >
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Which Kit to Order

Panels Blood Urine Misc
*TBD1 | Tick Borne Disease Panel 1
*CP1 | Co-infection Panel 1
*CP2 | Co-infection Panel 2
*CP3 | Co-infection Panel 3
CP4 | Co-infection Panel 4
CP5 | Co-infection Panel 5
EP1 | Ehrlichia Panel 1
(*) Not yet available for New York residents.

Collection Kits

Compatible with Samples Other than Blood or Urine

Misc. Collection Kit

The Miscellaneous Collection Kit is compatible with tick-borne disease tests that require samples other than blood or urine, such as cerebral spinal fluid (CSF), tissue, placenta or breast milk.

Compatible with All Tests that Require Blood

Blood Collection Kit

The Blood Collection Kit is compatible with most of the tick-borne disease tests and panels. The panels are usually the most comprehensive available for testing for Borreliosis/Lyme disease as well as co-infection(s) with other tick-borne illnesses.

Compatible with All Tests that Require Urine

Urine Collection Kit

The Urine Collection Kit is compatible with all tick-borne disease tests that require urine samples. These tests are particularly useful during the acute phase of a tick-borne disease infection before antibodies are present as well as for seronegative patients, patients with vague symptoms of long duration, and previously-treated patients with recurring symptoms.

Receipt of payment for the testing and a signed Requisition Form is required upon submission of patient's test specimen to IGeneX, with the exception of Medicare patients.