Cytomegalovirus (CMV): IgG, IgM and PCR

Cytomegalovirus (CMV) is very common: most people become infected in childhood or youth, usually without symptoms. Blood antibody testing shows whether you have had CMV before and helps assess recent infection, while PCR detects the virus itself in blood. Testing is most often requested by women planning pregnancy or already pregnant, and people with persistent fatigue and fever of unclear cause.

Who is this test for

• women planning pregnancy and pregnant women when a gynaecologist wants to know whether they have had CMV;
• pregnant women with flu-like fever and fatigue or fetal changes on ultrasound;
• people with mononucleosis-like symptoms (fever, fatigue, enlarged lymph nodes), particularly when tests for Epstein-Barr virus are negative;
• people with fever lasting weeks or unexplained high liver enzymes;
• people with weakened immunity, for example after transplantation or on immunosuppressive medicines, when a doctor checks by PCR whether the virus is active;
• women working with small children, for example in nurseries, who are planning pregnancy.

What the test reveals

CMV belongs to the herpesvirus group. It spreads through saliva, urine and other bodily fluids, often from young children, and after infection remains inactive in the body for life. In healthy adults, it usually passes unnoticed or as an illness resembling mononucleosis. It is particularly important in pregnancy because it is the most common cause of congenital infections and an important cause of hearing impairment in children; it is also dangerous with severely weakened immunity.

• CMV IgM appears first after infection and suggests recent or reactivated infection.
• CMV IgG appears later and remains for life, showing previous infection.
• Cytomegalovirus PCR detection does not measure antibodies; it detects the virus itself in blood. It is used in particular situations assessed by a doctor, most commonly with weakened immunity.

The test and preparation

Antibody testing requires venous blood, taking a few minutes, without special preparation. PCR also uses a blood sample. State whether you are pregnant, when symptoms began and whether you recently received blood or immunoglobulins, because these affect interpretation. Bring previous CMV results if available.

What your results mean

• IgG negative, IgM negative: you have not had CMV. Hygiene measures are then particularly important during pregnancy.
• IgG positive, IgM negative: you had the virus previously. Fetal risk during pregnancy is much lower than with a first infection but is not absent, so hygiene measures still apply.
• IgM positive: a recent infection is possible, but also viral reactivation, persisting IgM or a false-positive result. A doctor usually requests a new sample in two to three weeks and may also request IgG avidity, which indicates whether infection is recent.
• PCR positive: virus was detected in blood. What this means depends on your immunity and symptoms.
• PCR negative: virus was not detected in blood, which does not exclude previous infection.

Cut-offs are printed on the report. A doctor, or gynaecologist during pregnancy, interprets it alongside symptoms, examination and previous results.

How to arrange testing

You can come for blood collection without an appointment or referral at one of our branches throughout Croatia (listed on the Contactpage). Prices for all tests and panels are listed in the price list. If your doctor requests EBV antibodies alongside CMV, the Infectious Mononucleosis + CMV Panelis more cost-effective; during pregnancy, alongside toxoplasma, rubella and herpes simplex, the TORCH test.

Frequently asked questions

Is CMV dangerous?

Usually not for healthy children and adults: infection passes without symptoms or as a mild viral illness. It may be dangerous to the fetus if the mother is infected during pregnancy, and to people with severely weakened immunity.

How can I reduce CMV risk during pregnancy?

Avoid contact with young children’s saliva and urine. Do not share cups or cutlery with a child, do not kiss them on the mouth, and wash hands after changing nappies, feeding and wiping noses. These measures also apply with positive IgG.

Can CMV cause mononucleosis-like symptoms?

Yes. Fever, fatigue and enlarged lymph nodes may result from CMV, while the rapid mononucleosis test is then usually negative. EBV and CMV antibodies are therefore often tested together for such symptoms.

Can I become infected with CMV again?

After the first infection, the virus remains in the body and may occasionally reactivate; infection with another strain is also possible. In healthy people, this usually causes no symptoms.