Cytomegalovirus IgG & IgM antibodies

About Test:

Cytomegalovirus is a member of Herpes virus family. It is related to the family of virus that cause chicken pox, herpes simplex and mononucleosis.

CMV is a common virus that can infect almost anyone.

It is an infection which is common in human beings and is usually mild and asymptomatic.

Once infected it remains in the body for life. But in a healthy individual, it may lie dormant in the body and get reactivated. When there is active viral infection in the body, the virus can spread from person to person through body fluids such as blood, saliva, urine, tears, semen, vaginal fluid and breast milk. Casual contact doesn’t transmit CMV.

Different types of Cytomegalo virus CMV infection.

• Congenital - This is when a baby gets CMV from its mother before birth.
• Primary - This is the first time someone gets CMV. It usually doesn’t cause symptoms, but some people may have signs that look like mononucleosis.
• Reactivation -  An infection that has been dormant can become active again when the immune system is weakened like in HIV infection, those getting treatment for cancer, or those who have had an organ transplant.

Since a majority of CMV infections remain asymptomatic, it is often difficult to diagnose CMV infection based on symptoms alone.

Investigations used to Diagnose CMV infection: Serologic tests detect CMV antibodies IgM and IgG

• CMV IgM:  CMV IgM detection is a sensitive marker of primary CMV infection, but CMV IgM is also produced during Non Primary CMV infections like viral reactivation or if there is reinfection with exogenous virus. It has also been found that IgM persists for a long term following primary infection in some individuals.
   
• CMV IgG: A positive test for CMV IgG indicates that a person was infected with CMV at some time during their life but does not indicate when a person was infected. This applies for persons ≥12 months of age when maternal antibodies are no longer present. Measurement of CMV IgG in paired samples taken one to three months apart can be used to diagnose primary infection; seroconversion (1^st sample IgG negative, 2^nd sample IgG positive) is clear evidence for recent primary infection.
  
  If primary infection needs to be excluded, All CMV IgG positive (reactive) samples should be tested for

               i. CMV IgM

              ii. CMV IgG Avidity Test