- Red or tiger top tube
- 5-7 mL of venous blood
- Capillary tube from newborn heelstick or cord sample
Additional information
- Handle sample gently to prevent hemolysis
- Send sample to lab immediately
- Reject samples that are lipemic, icteric, contaminated, heat-inactivated or hemolyzed
- Paired serum samples are preferred with one blood sample taken upon suspicion of CMV, and another one taken within 2 weeks
- Cytomegalovirus antibody testing provides a qualitative and quantitative analysis of antibodies to cytomegalovirus (IgM, IgG) in the blood
- Cytomegalovirus is a double-stranded DNA virus of herpesviridae family designated as human herpesvirus–5 (HHV-5)
- CMV is the major cause of non-Epstein-Barr virus infectious mononucleosis like syndromes in the general population and is an important pathogen causing a variety of disease in immunocompromised hosts
- CMV infection occurs worldwide affecting all geographic regions and socioeconomic groups, but is widespread in developing countries and lower socioeconomic groups
- The CMV antibody test is indicated in the following conditions:
- Persons with symptoms of infectious mononucleosis but with negative monospot / Epstein Barr virus test results
- Immunocompromised persons
- Donors and recipients of blood/ blood products and organ transplants
- In pregnant women as a part of the TORCH panel
- Infants born to CMV infected mothers
- To screen for CMV infection in infants who require blood transfusions or tissue transplants
- Persons presenting with signs of hepatitis, but with negative hepatitis testing for hepatitis A, B, and C
- To discriminate between current infection (IgM) and prior infections (IgG)
- Transmission of CMV primarily occurs from person to person contact through body fluids such as saliva, urine, blood, tears, and semen. CMV can be sexually transmitted and can also be transmitted via breast milk, transplanted organs, and from blood transfusions
- CMV infection is most often acquired during childhood and is usually asymptomatic. In some cases it will manifest as a mononucleosis-like syndrome with prolonged fever and mild hepatitis. Typically there are no long term complications in immunocompetent persons
- Once a healthy person becomes infected with CMV, the virus remains alive and continues to harbor usually in dormant stage, within that person's body for life. CMV can reactivate intermittently, often sub-clinically, shedding small amounts of virus into body fluids but not causing symptoms
- Reactivation of latent infection or primary infection in immunocompromised persons such as HIV-infected, solid organ transplant, bone marrow transplantation, and on chemotherapy, may be seen clinically as:
- Fever of unknown origin
- Pneumonia
- Hepatitis
- Encephalitis
- Myelitis
- Colitis
- Uveitis
- Retinitis
- Neuropathy
- Organ rejection
- Infants who acquire CMV from a pregnant mother with a primary infection are prone to develop severe cytomegalic inclusion disease which includes:
- Petechiae (71%)
- Jaundice (67%)
- Splenomegaly
- Thrombocytopenia (77%)
- Intrauterine growth retardation (50%)
- Microcephaly (53%)
- Retinitis
- Mental retardation
- Deafness
- Motor dysfunction
- CMV antibodies
- CMV immunoglobulins
- IgM antibodies appear by 1-2 weeks post exposure and may persist for 16-20 weeks after initial infection
- IgM antibodies may also be detectable when latent CMV infection is reactivated
- IgG antibodies appear 2-4 weeks after CMV exposure and typically last a lifetime
- The presence of IgM or a fourfold or greater rise in IgG titer suggests recent infection
- IgM antibody to CMV in cord or infant blood is diagnostic of congenital CMV infection
- Presence of IgG antibodies in infants up to 6 months of age may be of maternal origin, but a rising or persistent IgG titer even after 6 months is indicative of congenital CMV infection, which should be confirmed by viral culture or viral antigen testing
- Antibodies to CMV can be detected by several methods such as:
- Enzyme immunoassay
- Indirect immunofluorescence
- Latex agglutination
- Passive hemagglutination
Additional information
- Approximately 50-85% of Americans have had CMV infection by age 40 years
- Isolation of CMV from urine or saliva in the first 1-2 weeks of life is the standard procedure for diagnosis of congenital CMV disease
- As both CMV and HIV-1 are immunosuppressive, these two viruses may act additively or synergistically to accelerate HIV-1 disease progression
- Antibody results must be evaluated in the context of the patient's current clinical symptoms and viral culture results
- Related laboratory tests include
- Antigen Testing
- Culture
- Direct Examination - histology
- EBV testing
- HIV testing
- Monospot
- TORCH panel
Consult your laboratory for their normal ranges as these may vary somewhat from the ones listed below.
- CMV IgG: Negative (< 1:16)
- CMV IgM: Negative (< 1:8)
ELISA testing has a different scale for negative/positive
- IgM Titers
0.89 IV: Negative- 0.90-1.09 IV: Equivocal
1.10 IV: Positive- IgG Titer
- 0.89 IV: Negative
- 0.90-1.09 IV: Equivocal
- 1.10 IV: Positive
For acute infection, IgM is typically positive and IgG is negative. A positive IgG with a negative IgM typically represents previous (not acute) infection. Titers may also be serially followed to see if there is a pattern of rise or fall in the titers.
- A high result is consistent with either current or prior infection
- False positives may occur
- For acute infection, IgM is typically positive (or negative if not enough time to form antibody has been allowed) and IgG is negative
- For previous infection, a positive IgG with a negative IgM is typical
- IgM may also become positive transiently in cases of reactivation of latent CMV
- Titers may also be serially followed to see if there is a pattern of rise or fall in the titers
False positive results may be found in:
- Antinuclear antibody positive patients
- Epstein-Barr virus infections
- Herpes simplex virus
- Infectious mononucleosis
- Measels
- Rheumatoid factor
- Varicella-Zoster
A negative result is useful as a screening test in low probability patients. In patients with a clinical scenario likely to be CMV infection, a false negative result must be considered.
False negative results may occur if:
- The treatment was begun before antibodies developed
- The test was done < 2 weeks after exposure to the virus (for IgM) or < 4 weeks (for IgG).
- ARUP Laboratories®. Cytomegalovirus Antibody, IgG. [Homepage on the internet]©2007. Last updated in September 2006. Last accessed on February 3, 2007. Available at URL: http://www.aruplab.com/guides/ug/tests/0050165.jsp
- ARUP Laboratories®. Cytomegalovirus Antibody, IgM. [Homepage on the internet]©2006. Last updated in September 2006. Last accessed on February 3, 2007. Available at URL: http://www.aruplab.com/guides/ug/tests/0050553.jsp
- Centers for Disease Control: Cytomegalovirus (CMV). [Homepage on the Internet]. Last reviewed on August 15, 2005. Last accessed on February 3, 2007. Available at URL: http://www.cdc.gov/cmv/clinicians.htm
- eMedicine from WebMD®. Cytomegalovirus. [Homepage on the Internet] ©1996-2007. Last updated on August 11, 2006. Last accessed on February 3, 2007. Available at URL: http://www.emedicine.com/med/topic504.htm
- Galadari I et al. Rapid detection of IgM and IgG antibodies to herpesviridae virus. Allerg Immunol (Paris). 2006 Jun; 38(6): 198-202.
- Genser B et al. Evaluation of five commercial enzyme immunoassays for the detection of human cytomegalovirus-specific IgM antibodies in the absence of a commercially available gold standard.Clin Chem Lab Med. 2001 Jan;39(1):62-70.
- HIV InSite®. Cytomegalovirus and HIV. [Homepage on the Internet]©2007. Last updated in May 2006. Last accessed on February 3, 2007. Available at URL: http://www.hivinsite.org/InSite?page=kb-05-03-03
- Kapusta M et al. Detection of cytomegalovirus in infant cerebrospinal fluid by conventional PCR, nested PCR and PCR-Digene. Acta Microbiol Pol. 2001; 50(3-4): 263-74.
- LabTestsOnline®. CMV. [Homepage on the Internet] ©2001-2007. Last reviewed on October 26, 2005. Last accessed on February 3, 2007. Available at URL: http://www.labtestsonline.org/understanding/analytes/cmv/test.html
- MedlinePlus Medical Encyclopedia®. CMV serology test. [Homepage on the Internet]©2005. Last updated on November 16, 2005. Last accessed on February 3, 2007. Available at URL: http://www.nlm.nih.gov/medlineplus/ency/article/003546.htm
- Schleiss et al. Protection against congenital cytomegalovirus (CMV) disease, conferred by a replication-disabled, bacterial artificial chromosome (BAC)-based DNA vaccine. Vaccine. 2006 Sep 11; 24(37-39): 6175-86. Epub 2006 Jul 18.
- Weber B et al. Human cytomegalovirus infection: diagnostic potential of recombinant antigens for cytomegalovirus antibody detection. J Virol Methods. 2001 Aug; 96(2): 157-70.