Diagnosis of Cytomegalovirus (CMV)
Diagnosis of cytomegalovirus (CMV) depends on the clinical context—whether the patient is a healthy adult, pregnant woman, immunocompromised individual, or a newborn. Since many cytomegalovirus (CMV) infections are asymptomatic or mimic other illnesses, laboratory testing is essential for confirmation. Accurate and timely diagnosis is particularly important in cases of congenital infection or severe illness in people with weakened immune systems.
Serological Tests
These blood tests detect antibodies produced in response to CMV:
IgM antibodies: Indicate recent or current infection
IgG antibodies: Indicate past exposure and immunity
A rise in IgG levels over time suggests a recent infection. Serological testing is commonly used in pregnant women to determine whether CMV exposure occurred during pregnancy, which could affect the unborn child.
Polymerase Chain Reaction (PCR)
Detects CMV DNA in blood, urine, saliva, or cerebrospinal fluid
Especially useful for monitoring viral load in immunocompromised individuals, such as transplant recipients or HIV patients
Highly sensitive and can track the effectiveness of antiviral treatment
Culture and Antigen Detection
CMV cultures are sometimes grown from bodily fluids or tissue samples, although this method is slower and less commonly used today
Antigen detection tests may identify viral proteins in white blood cells and are often used alongside PCR
Congenital CMV Diagnosis | Diagnosis of Cytomegalovirus (CMV)
If congenital CMV is suspected:
Testing should be done within the first three weeks of life
Saliva or urine samples are used for PCR testing
Later testing may not differentiate between congenital and acquired postnatal infection
Hearing tests and neuroimaging may also be recommended to assess the impact of infection on the baby’s development.
Biopsy and Imaging
In severe cases affecting organs:
A biopsy of affected tissue (e.g. gut, liver, or retina) may reveal inclusion bodies characteristic of CMV
CT scans or MRIs may be used to assess brain inflammation or other complications
Screening Limitations
Routine screening for CMV is not currently recommended for the general population. However, targeted screening is vital in:
Pregnant women with suspected infection
Organ or bone marrow transplant patients
Infants with abnormal findings at birth
In summary, diagnosis of cytomegalovirus (CMV) involves a combination of serological, molecular, and sometimes imaging techniques. Early and accurate diagnosis guides appropriate care, especially in high-risk patients or in preventing congenital complications.
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