Skip to contentSkip to navigation

Anti-cytomegalovirus IgG


Cytomegalovirus (CMV) is a common virus. In North America, between 50% and 85% of the population has had a CMV infection, usually during childhood, without experiencing any symptoms (influenza- or mononucleosis-like symptoms). The body defends against a CMV infection by first producing IgM antibodies, which gradually disappear and are replaced after a few months by IgG antibodies, which remain detectable for the rest of that person’s life. For its part, the CMV virus is still present, but in a latent form that can, however, be reactivated.

Positive CMV IgG and IgM test results in a symptomatic individual likely indicate a recent first-time exposure to CMV or a reactivation of the virus. IgG retesting two to three weeks later is done to confirm an active infection. If the exposure is very recent, the results might be positive for IgM only. When the IgG and IgM results are both negative in a symptomatic person, these symptoms are probably not due to the CMV, and the person’s immune system probably has an abnormality and is not producing enough antibodies.

Term of the Week

Hot zone

A hot zone is a section of a facility (sometimes an entire facility or even a city district) where there is a high risk of contamination by patients with an infectious disease. All individuals entering a hot zone must respect appropriate protective measures. By analogy, “cold zone” and “warm zone” are used to refer to areas where there is no infected individual or only individuals suspected of having an infection.