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Cytomegalovirus test: who, why and what the results mean
«"Why is this virus known to everyone, but almost no one talks about it?"»
Cytomegalovirus (CMV) is one of the most common viruses in the world. Most infected people do not even realize they have it. However, in some situations — especially in pregnant women, newborns, and people with weakened immune systems — he can become a serious threat. That's why cytomegalovirus test is an important part prenatal, immunological and infectious screening.
What is cytomegalovirus?
CMV belongs to the herpesvirus family (Herpesviridae) and has the property of remaining in the body in a latent state throughout life. It is transmitted:
through saliva, tears, blood, semen, breast milk
during childbirth (vertical route)
organ transplantation
with immunosuppression (after chemotherapy or HIV infection) - may reactivate
In healthy adults, CMV usually causes no symptoms or manifests as a mild cold. But in pregnant women, it is a potential factor of congenital infections, and in people with immunosuppression — serious complications (encephalitis, pneumonia, eye, liver, intestinal damage).
When is a cytomegalovirus test ordered?
At planning pregnancy or during the first trimester
In case fetal developmental delays or birth defects
У newborns with suspected congenital infection
У patients with immunodeficiency (HIV, post-transplant, cancer patients)
At unexplained fevers, enlarged lymph nodes, eye damage
For disease activity control with already known CMV infection
What are the tests for cytomegalovirus?
1. ELISA (enzyme-linked immunosorbent assay) for IgM and IgG antibodies
IgM — indicates acute phase or recent infection
IgG — shows that the body has already encountered the virus
Additionally, they determine IgG avidity — to clarify the time of infection
High IgG avidity - long-standing infection
Low IgG avidity – recent infection (dangerous during pregnancy)
2. PCR (polymerase chain reaction)
Determines Virus DNA in blood, urine, saliva, cerebrospinal fluid
Allows detect active replication
It is used when serious organ damage, congenital CMV infection
3. Cultural study (virology)
Used less often due to duration
Relevant when assessing prolonged carriage in newborns
How to prepare for the analysis
ELISA – does not require special preparation, is taken in the morning on an empty stomach
PCR – it is better to take it before starting antiviral therapy
It is worth informing the doctor about pregnancy, immunodeficiency, chronic diseases
How to interpret the results
| Indicator | Value |
|---|---|
| IgM – / IgG – | The patient has never been in contact with CMV |
| IgM + / IgG – | Acute primary infection (dangerous during pregnancy) |
| IgM+/IgG+ | Possible recent infection or reactivation |
| IgM – / IgG + | Immunity after past exposure (carrier, safe for most) |
In difficult cases, it is important IgG avidity assessment and PCR to confirm active replication.
What to do if you test positive
At high avidity IgG – no specific treatment is required
At acute infection in a pregnant woman – consultation with an infectious disease specialist and geneticist is indicated
У newborns or immunocompromised individuals – possible prescription of antiviral drugs (ganciclovir, valaganciclovir)
Necessary dynamic observation and monitoring viral load
The cytomegalovirus test is a tool not only for detecting infection, but also for risk assessment, prognosis and determination of treatment tactics. Especially in vulnerable categories of patients - newborns, pregnant women, cancer patients and immunosuppressed patients.
