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Cytomegalovirus

Cytomegalovirus, a herpes viral genus, is known in humans as HCMV. It is part of the Betaherpesvirinae subfamily. Other herpesviruses fall into the subfamilies of Alphaherpesvirinae or Gammaherpesvirinae.

xHCMV infections are frequently associated with salivary glands. It can be lethal for people who are immunocompromised. Other CMV viruses are found in several mammal species, but species isolated from animals differ from HCMV in terms of genomic structure.

HCMV is found all over the world and throughout varied socioeconomic groups. It infects between 50% and 80% of adults in the US. 58.9% of those over 6 are infected with CMV while 90.8% of those over 80 test positive for HCMV. It is most commonly transmitted to a developing fetus. It is more widespread in developing countries. Most healthy people who are infected after birth have no symptoms although some people develop symptoms similar to mononucleosis or glandular fever. Sometimes they receive a sore throat. The virus remains latent after infection passes. Actual disease only occurs when immunity is suppressed by drugs, infection, or old age. The virus follows its initial infection by residing in T-cells.

CMV may be shed in bodily fluids including urine, saliva, blood, tears, semen, and breast milk. High risk groups include pre-natal and postnatal infants, immunocompromised people, and people with leukemia. Lytically replicating virus disrupts the cytoskeleton, causing massive cell enlargement, which is the source of the virus’ name. Although not highly contagious it can been spread in households and among young children in day care centers. Hand washing is an easy way to minimize the spread of CMV.

HCMV is a TORCH infection that leads to congenital abnormalities. TORCH stands for: toxoplasmosis, rubella, herpes simplex, and cytomegalovirus. Cogenital infection occurs when the mother suffers a primary infection during pregnancy. 5% develop multiple handicaps, and develop cytomegalic inclusion disease. Another 5% develop cerebral calcification. Primary CMV infection can lead to a weakened immune system or even worse a more common problem is reactivation of the latent virus.

In immuno-supressed people CMV can lead to fulminant liver failure, cytomegalovirus colitis, CMV pneumonitis, and CMV esophagitis. If a patient receives a transplant from someone infected with CMV then the patient will need prophylactic treatment with valganciclovir or ganciclovir. As long as it is treated early any life threatening infection can be prevented.

Often, CMV is not diagnosed because symptoms don’t usually manifest. Also, those infected develop lifelong anti-bodies to CMV. Generally, CMV is suspected when mononucleosis symptoms are present but that when tested return negative. Diagnostic tests are best performed by using paired serum samples. One blood test is taken upon suspicion while another should be taken 2 weeks later. Immunosorbent assay is the most commonly available serologic test for measuring antibody to CMV. The result determines if acute infection, prior infection, or passively acquired maternal antibody in an infant is present. CMV assays are part of the standard screening for non-directed blood donation. In the U.S. CMV-negative donations are earmarked for transfusion to infants or immuno-compromised patients.

Cytomegalovirus


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