Viral Serologies: IgG vs. IgM for EBV, CMV, Parvovirus, and When to Suspect Each Infection
Viral Serologies: IgG vs. IgM for EBV, CMV, Parvovirus, and When to Suspect Each Infection IgM means acute. IgG means past. Except when it doesn't. Here's how to interpret the viral serology panel without getting fooled. The Universal Principle: IgM vs. IgG IgM : The first antibody produced during acute infection. Appears within days to 1–2 weeks of infection. Generally indicates acute or recent infection. Declines over weeks to months. IgG : Appears later (2–4 weeks), rises during convalescence, and persists for years to lifetime . Indicates past exposure/immunity. IgM positive + IgG negative = early acute infection (seroconversion in progress) IgM positive + IgG positive = recent or acute infection (IgG just appearing) IgM negative + IgG positive = past infection/immunity Both negative = no exposure (susceptible) The IgM Caveat IgM is NOT always reliable for timing. False-positive IgM can occur with: polyclonal immune activa...