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HelpTest Code BABG Babesia microti IgG Antibodies, Serum
Reporting Name
Babesia microti IgG Ab, SUseful For
An adjunct in the diagnosis of babesiosis
Follow-up of documented babesiosis
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 |
| 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
86753
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| BABG | Babesia microti IgG Ab, S | 16117-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 81128 | Babesia microti IgG Ab, S | 16117-4 |
Clinical Information
Babesiosis is a zoonotic infection caused by the protozoan parasite Babesia microti. The infection is acquired by contact with Ixodes ticks carrying the parasite. The deer mouse is the animal reservoir, and overall, the epidemiology of this infection is much like that of Lyme disease. Babesiosis is most prevalent in the Northeast, upper Midwest, and Pacific Coast of the United States.
Infectious forms (sporozoites) are injected during tick bites, and the organism enters the vascular system where it infects red blood cells (RBC). During this intraerythrocytic stage, it becomes disseminated throughout the reticuloendothelial system. Asexual reproduction occurs in RBC, and daughter cells (merozoites) are formed that are liberated on rupture (hemolysis) of the RBC.
Most cases of babesiosis are subclinical or mild, but the infection can be severe and life-threatening, especially in older or asplenic patients. Fever, fatigue, malaise, headache, and other flu-like symptoms occur most commonly. In the most severe cases, hemolysis, acute respiratory distress syndrome, and shock may develop. Patients may have hepatomegaly and splenomegaly.
A serologic test can be used as an adjunct in the diagnosis and follow-up of babesiosis, when infection is chronic or persistent, or in seroepidemiologic surveys of the prevalence of the infection in certain populations. Babesiosis is usually diagnosed by observing the organisms in infected RBC on Giemsa-stained thin blood films of smeared peripheral blood. Serology may also be useful if the parasitemia is too low to detect or if the infection has cleared naturally or following treatment.
Interpretation
A positive result of an indirect fluorescent antibody test (titer ≥1:64) suggests current or previous infection with Babesia microti. In general, the higher the titer, the more likely it is that the patient has an active infection. Patients with documented infections have usually had titers ranging from 1:320 to 1:2560.
Cautions
Previous episodes of babesiosis may produce a positive serologic result.
In selected cases, documentation of infection may be attempted by animal inoculation or polymerase chain reaction (PCR) methods (LBAB / Babesia species, Molecular Detection, PCR, Blood).
Performance characteristics have not been established for the following specimen characteristics:
-Lipemic
-Hemolyzed
Method Description
The patient’s serum is diluted and is placed in microscopic slide wells, which have been coated with Babesia microti-infected red blood cells from Syrian hamsters. 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 intraerythrocytic organisms constitutes a positive reaction.(Krause PJ, Telford III SR, Ryan R, et al. Diagnosis of babesiosis: Evaluation of a serologic test for the detection of Babesia microti antibody. J Infect Dis. 1994;169[4]:923-926; package insert: Babesia IFA IgG. DiaSorin Molecular; 8/12/2016)