Positive EBV IgM indicates a recent or acute Epstein–Barr virus infection, commonly causing infectious mononucleosis. IgM antibodies appear early and usually wane within weeks to a few months. Results should be interpreted with symptoms and follow-up testing—EBV IgG, heterophile test, repeat serology or PCR—because false positives, cross‑reactivity, or lab variation can occur. Reactivation typically shows IgG without IgM.

EBV IgM appears early in acute infection, usually detectable at symptom onset and generally remains positive for about 4–12 weeks (commonly 4–6 weeks). In some people it may persist longer, up to 3 months or occasionally several months; after that IgG and EBNA patterns help determine past infection. If results are unclear or symptoms continue, repeat testing or clinical review is advised.

A positive Epstein‑Barr virus (EBV) test usually means you have been infected: IgM indicates recent or active infection, while IgG shows past exposure and immunity. Active EBV can cause infectious mononucleosis—fatigue, sore throat, fever, swollen lymph nodes—and most cases resolve with rest and fluids. Complications are uncommon but possible, especially if immunocompromised. Your clinician may recommend follow‑up testing and supportive care or monitoring.

Cost varies: in public healthcare systems the EBV IgM test is typically provided free to patients. In private settings it ranges roughly $20–$200 in the U.S. and about ₹400–₹1,200 in India; specialty labs or bundled panels may cost more. Prices depend on the lab, location and whether insurance covers testing, so check your local provider for exact charges.

Epstein‑Barr virus (EBV) is an infectious herpesvirus, not an autoimmune disease. However, EBV can trigger immune dysregulation and is associated with increased risk of some autoimmune conditions (for example, multiple sclerosis and systemic lupus erythematosus) and certain cancers. Rarely, chronic active EBV causes prolonged illness. Diagnosis and management differ from primary autoimmune diseases and need medical evaluation.

IgM and IgG are antibody classes with different roles. IgM is produced first in an infection, is a large pentamer that activates complement strongly, and indicates recent or acute exposure. IgG appears later, is a smaller monomer that provides long-lasting, specific immunity and immune memory, can cross the placenta, and is the main mediator of long-term protection after infection or vaccination.