The presence of IgG antibodies in a single specimen is not sufficient to distinguish between active or past infection.
Patients suspected of having primary or active infection could be tested for the presence of IgM antibodies to CMV or CMV DNA by PCR.
Individuals with acute CMV infection may not exhibit any detectable IgG antibodies at the early stage of infection.
False reactive results may also occur in patients with measles, VZV, HSV, or EBV. Samples containing antinuclear antibodies or other anticell antibodies may give false reactive results.
Results may be affected if patient has developed heterophilic antibodies due to exposure to animal based protein.
False negative results may occur in immunocompromised patients.