CYTOMEGALOVIRUS

IgG , IgM

• Negative : ≤0.90 Od ratio
• Equivocal: 0.91 – 1.10 Od ratio
• Positive: ≥ 1.11 Od ratio

• CMV is a member of the herpes virus group, and most frequently transmitted to a developing child before birth. Once a person becomes infected, the virus remains alive, but usually dormant within that person’s body for life. CMV usually causes no symptoms or only mild illness. Individuals with mild illness may have non specific signs and symptoms such as sore throat, fever, tiredness, and swollen glands. CMV may sometimes cause s/s similar to mononucleosis. CMV spreads through infected bodily fluids (Urine, saliva, blood, tears, semen, and breast milk) or contact with contaminated objects.
• A pregnant woman infected with CMV can pass the infection to her baby through the placenta. This can cause serious physical and developmental problems in the baby. Most new borns who are infected appear normal but may later develop hearing or vision problems, pneumonia, seizures, and/or delayed mental developments
• CMV can cause serious illness and death in people with weakened immune system
• Two classes of CMV antibodies tests are done; IgM antibodies are produced by the body first in response to a CMV infection. They can be detected in the blood within a week or two after the initial exposure. IgM titres rise for a short time, then decline and usually fall below detectable levels after a few months. IgM antibody levels rise again when latent CMV is reactivated
• IgG antibodies are produced several weeks after the initial CMV infection. IgG levels rise during the active infection, then stabilize as the CMV infection resolves and the virus becomes inactive. Once exposed IgG antibody is present for the rest of life, which provides protection from getting another primary infection.
• Polymerase chain reactions (PCR) is used to diagnose congenital infections in newborns
• CMV testing is done for screening of immune suppressed patients, screening of organ transplant patients and blood donor screening

Interpretations

• A positive result is indicative of either recent active infection (up to 8 months before test) or secondary infection of latent virus or re infection.
• A negative result, however does not always rule out acute infection, because either the infection is in its early stage and the patient may be still unable to synthesize CMV specific IgM, or the patient is immunocompromised. A second sample should be collected if the first is negative in not less than one week.
• CMV IgG appears about 1-2 weeks later after IgM antibody appears. Specific IgG assay is useful in distinguishing subjects having acquired the disease from those who have not.