Brucella IgM Test Overview
The Brucella IgM test is a serological assay, typically ELISA-based, that detects IgM antibodies specific to Brucella species (e.g., B. abortus, B. melitensis, B. suis), indicating acute or recent infection with this intracellular zoonotic bacterium common in livestock and unpasteurized dairy exposure.
It measures early immune response, often combined with IgG for full serologic profiling, and may reflex to confirmatory agglutination tests like tube agglutination or Coombs for titer accuracy.
Indications of Brucella IgM Test
Primarily indicated for acute brucellosis suspicion in patients with undulant fever, drenching night sweats, profound fatigue, arthralgias/myalgias, hepatosplenomegaly, or orchitis/epididymitis; high-risk groups include pastoralists, veterinarians, slaughterhouse workers, lab personnel, and travelers to endemic areas like East Africa.
Also used for early screening in pregnancy (risk of miscarriage), blood donors, or post-exposure prophylaxis monitoring; IgM rises within 7-10 days of infection onset.
Patient Preparation/Instructions
No fasting or special prep required
Collect 3-5 mL venous blood in a plain red-top or serum separator tube (SST), allow clotting at room temp, centrifuge promptly.
Avoid recent (within 2 weeks) antibiotics, steroids, or Brucella vaccines that may blunt response
Disclose travel history, animal exposure, or raw milk consumption to clinician. Ship refrigerated if not same-day processing; hemolyzed/lipemic samples rejected
Reference Values
Typically: <0.80
Negative; 0.80-1.09
Equivocal; ≥1.10 Positive.
IgM suggests recent infection but may persist months; interpret with clinical context and IgG. Lab-specific ranges apply.
Report Turnaround
Results generally ready in 1-5 days; reflex agglutination adds 1-2 days depending on lab volume.
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