Sign in →

Test ID: ANAP Anaplasma phagocytophilum (Human Granulocytic Ehrlichiosis) Antibody, Serum

Reporting Name

Anaplasma phagocytophilum Ab, IgG,S

Useful For

As an adjunct in the diagnosis of human granulocytic ehrlichiosis (anaplasmosis)


Seroepidemiological surveys of the prevalence of the infection in certain populations

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.


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 EHRL / Ehrlichia/Anaplasma, Molecular Detection, PCR, Blood).

Testing Algorithm

For more information see Acute Tick-Borne Disease Testing Algorithm.

Report Available

1 to 3 days

Day(s) Performed

Monday through Friday

Clinical Reference

Center for Disease Control and Prevention (CDC): Tickborne Diseases of the United States: A Reference Manual for Healthcare Providers. 6th ed. US Department of Health and Human Services; 2022. Accessed September 29, 2022. Available at

Method Name

Immunofluorescence Assay (IFA)

Specimen Type


Specimen Required

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

Reference Values


Reference values apply to all ages.

Test Classification

This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


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
Mayo Clinic Laboratories | Neurology Catalog Additional Information:

mml-CNS-Infections, mml-Pediatric