Background Information

Human Cytomegalo Virus (CMV)

CMV belongs to the family of herpesviridae which also includes Herpes Simplex virus type 1 and 2, Varicella- zoster virus and Epstein-Barr virus. The CMV is found universally throughout all geographic locations and socioeconomic groups; it infects between 50% and 85% of adults. CMV is also the virus most frequent transmitted to a developing child before birth. It is primarily a sexually transmitted disease, but it can also be transmitted from mother to child, via blood transfusions, organ transplantation and close contact. For most healthy persons who acquire CMV after birth, few symptoms are noticed and long term health conditions are seldom seen. Some infected persons experience mono-nucleosis-like syndrome symptoms with fever and mild hepatitis. The CMV is an opportunistic pathogen and is usually dormant within the infected person for life. Although the CMV is not a serious problem, it is important to certain high-risk groups, i.e. unborn baby during pregnancy, people who work with children and immunocomprised persons, such as transplant recipients and persons infected with human immunodefiency virus (HIV). The virus can be found in lung, kidney, gut and other organs and may be shed in bodily fluids of any infected person. An infection with CMV can cause a variety of inflammatory conditions, either localized or disseminated.

The incidence of primary CMV infection in pregnant women varies from 1% to 3%; healthy pregnant women are not at special risk from CMV infection. Their developing unborn babies may be at risk for congenital CMV disease causing generalized infection which symptoms may range from moderate liver and spleen enlargement to fatal illness. The average transmission rate to the fetus in primary maternal infection is 40% with a reported range of 24% to 75%. With treatment, most infected infants will survive; however within the first years of life 80% will have complications that may include hearing loss, vision impairment, hepatitis, pneumonia, purpera, thrombocytopenia and various degrees of mental retardation. These risks however, appear to be almost exclusive associated to those women who are having their first infection during pregnancy.

Infection with CMV is a major cause of disease and death in immunocomprised patients, including organ transplant recipients, hemodialysis patients, cancer patients, patients receiving immunosuppressive drugs and HIV infected patients. Common manifestations of the disease are pneumonia, retinitis (especially in HIV patients) CMV colitis and encephalitis. Whenever possible, patients should be given organs and/or blood that are CMV free.

The most used method for detection of CMV infections is the detection of antibodies by enzyme linked immunosorbent assay (ELISA) and by the growth of virus in tissue culture. However, the ELISA test may not be the adequate method in immunocomprised patients and newborns and antibodies used can cross-react with other species. Culturing the virus usually takes several weeks. With PanPath's REMBRANDT® kit for CMV, ISH analysis for viral DNA is less sensitive when compared to culture, but diagnosis can be obtained within one day. ISH is therefore a good alternative to ELISA, virus culture and PCR tests, especially for early stages of infection.

PanPath's Rembrandt® kit for CMV targets the 235 Kb total genome and shows no cross-hybridization with target DNA of EBV, HSV type 1/2 or other viruses, provided that the hybridization conditions as laid out in the protocol are strictly followed.