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HelpTest Code ANAP Anaplasma phagocytophilum (Human Granulocytic Ehrlichiosis) Antibody, Serum
Reporting Name
Anaplasma phagocytophilum Ab, IgG,SUseful For
As an adjunct in the diagnosis of human granulocytic ehrlichiosis (anaplasmosis)
Seroepidemiological surveys of the prevalence of the infection in certain populations
Testing Algorithm
For more information see Acute Tick-Borne Disease Testing Algorithm.
Method Name
Immunofluorescence Assay (IFA)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.4 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
| Heat-inactivated specimen | Reject |
Special Instructions
Reference Values
<1:64
Reference values apply to all ages.
Day(s) Performed
Monday through Friday
CPT Code Information
86666
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| ANAP | Anaplasma phagocytophilum Ab, IgG,S | 23877-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 81157 | Anaplasma phagocytophilum Ab, IgG,S | 23877-4 |
Clinical Information
Anaplasma phagocytophilum is an intracellular rickettsia-like bacterium that preferentially infects granulocytes and forms inclusion bodies, referred to as morulae. A phagocytophilum is transmitted by Ixodes species ticks, which also transmit Borrelia burgdorferi and Babesia species. Infection with A phagocytophilum is also referred to as human granulocytic anaplasmosis (HGA) or human granulocytic ehrlichiosis, and symptoms in otherwise healthy individuals are often mild and nonspecific, including fever, myalgia, arthralgia, and nausea. Clues to the diagnosis of anaplasmosis in a patient with an acute febrile illness after tick exposure include laboratory findings of leukopenia or thrombocytopenia and elevated liver enzymes. HGA is most prevalent in the upper Midwest and in other areas of the United States that are endemic for Lyme disease.
Interpretation
A positive result of an immunofluorescence assay (IFA) test (titer ≥1:64) suggests current or previous infection with human granulocytic ehrlichiosis (anaplasmosis). In general, the higher the titer, the more likely it is that the patient has an active infection.
Seroconversion may also be demonstrated by a significant increase in IFA titers.
During the acute phase of the infection, serologic tests are often nonreactive, polymerase chain reaction (PCR) testing is available to aid in the diagnosis of these cases (see EPCRB / Ehrlichia/Anaplasma, Molecular Detection, PCR, Blood).
Cautions
Previous episodes of human granulocytic ehrlichiosis (anaplasmosis) may produce a positive serologic result.
In rare instances, clinical evidence of infection may also be derived by direct microscopic examination of Giemsa- or Diff-Quik-stained peripheral blood buffy coat smears, which may reveal clusters of round, dark-purple stained, small dots (morulae) in the cytoplasm of polymorphonuclear cells. However, this is a very insensitive method.
Performance characteristics have not been established for hemolyzed or lipemic specimens.
Method Description
The patient's serum is diluted and is placed in microscopic slide wells that have been coated with Anaplasma phagocytophilum-infected cells. After incubation, the slides are washed and a fluorescein-isothiocyanate conjugate is added to each well. The slides are then read using a fluorescence microscope and significant fluorescent staining of intracellular organisms constitutes a positive reaction.(Dumler JS, Asanovich KM, Bakken JS, Richter P, Kimsey R, Madigan JE. Serologic cross-reactions among Ehrlichia equi, Ehrlichia phagocytophila, and human granulocytic Ehrlichia. J Clin Microbiol. 1995;33[5]:1098-1103; Pancholi P, Kolbert CP, Mitchell PD, et al. Ixodes dammini as a potential vector of human granulocytic ehrlichiosis. J Infect Dis. 1995;172[4]:1007-1012; package insert: Anaplasma phagocytophilum IFA IgG. DiaSorin Molecular; Rev. I, 08/12/2016)