cytomegalovirus CMV belongs to the family herpesvirus

the virus is so named decause it causes enlargment of the cells it infects

عفوا because وليس decause

Cytomegalovirus
Cytomegalovirus has the largest genome of all herpes viruses and appears only to replicate in human cells. Its name derives form the fact that, like other herpes viruses, it can form multinucleated cells (syncytia) with characteristically staining inclusions. Some cells such as macrophages and fibroblasts support a productive infection while a latent infection is set up in several cell types including T lymphocytes and stromal cells of the bone marrow. There is only one serotype.

Transmission
Cytomegalovirus infection is found in s significant proportion of the population. As with Epstein-Barr virus (also spread in saliva), seropositivity increases with age.
The virus is spread in most secretions, particularly saliva, urine, vaginal secretions and semen (which shows the highest titer of any body fluid). Cytomegalovirus infection is therefore sexually transmitted. It can also spread to a fetus in a pregnant woman and to the newborn via lactation, though there is some doubt about the importance of milk transmission. In the hospital, the virus can also be spread via blood transfusions and transplants. In third world countries with more crowded conditions, the virus is found in a much higher proportion of the population than in western countries.

Pathogenesis
Cytomegalovirus causes no symptoms in children and at most mild disease in adults .The virus first infects the upper respiratory tract and then local lymphocytes. Circulating lymphocytes then spread the virus to other lymphocytes and monocytes in spleen and lymph nodes. The virus finally spreads to a variety of epithelial cells including those of salivary glands, kidney tubules, testes, epididymis and cervix. Infection is usually asymptomatic (sub-clinical) but glandular fever is sometimes seen in young adults. The virus can inhibit T cell responses. The virus elicits both humoral antibodies and cell-mediated immunity but the infection is not cleared. Cell-mediated immunity, not humoral antibodies, controls the infection The importance of cell-mediated immunity stems from the possibility of spread from cell to cell. Although suppressed, the virus may later reactivate, particularly in cases of immunosuppression; indeed, infection by the virus can, itself, be immunosuppressive.

Congenital disease
There are two instances in which cytomegalovirus can cause serious disease. During a primary infection of the mother, the virus can spread via the placenta to the fetus and congenital abnormalities can occur; in fact, this virus is the most common viral cause of congenital disease. Up to one in forty newborns in the United States are infected by the virus. Abnormalities include microcephaly, rash, brain calcification and hepatosplenomegaly. These may result in hearing loss (bilateral or unilateral) and retardation. As might be expected, when reactivation occurs in a pregnant mother (usually reactivation in the cervix), the symptoms are less severe because of the mothers seropositivity. In this case, congenital abnormalities are rare.
Besides infection in utero, infants may be infected perinatally. As noted above, one tissue in which cytomegalovirus can set up a latent infection is the cervical epithelium and immunosuppression associated with pregnancy can lead to reactivation. About 50% of children born to such mothers are infected and can themselves shed virus within a few weeks. Also breast epithelium can harbor latent virus that may be similarly reactivated leading to infection of the infant. In neither case is there usually a problem and the infant remains asymptomatic.
Neonates may also receive the virus through infected blood transfusions. In this case, the amount of virus is much higher and symptoms may occur. These usually consist of pneumonia and hepatitis.

Disease in immunosuppressed patients
In patients who have received an organ transplant or have an immunosuppressive disease (e.g. AIDS), cytomegalovirus can be a major problem. Particularly important is cytomegalovirus-retinitis in the eye which occurs in up to 15% of all AIDS patients. In addition, interstitial pneumonia, colitis, esophagitis and encephalitis are seen in some patients.

Diagnosis
Most infections are asymptomatic and therefore go undiagnosed. There are fluorescent antibody and ELIZA tests. Multinucleated (cytomegalinic) cells with characteristic inclusions can be seen in biopsies of many tissues

Treatment
Ganciclovir, which inhibits the replication of all human herpes viruses, is usually used, especially to treat retinitis. Foscarnet is also approved in the US. Acyclovir is not effective. A vaccine is being developed but the best way to avoid the virus is to restrict contact between infected children and pregnant women. Also since cytomegalovirus is sexually transmitted, condoms can limit spread

؟Acyclovir is not effectiveسؤال لتنشيط الفكر: لماذا

cytomegalovirus (CMV)belongs to the family herpesvirus.the virus is so named because it causes enlargment of the cells it infects disease caused by CMV can occur as a congenital ,neonatal,or childhood infection. only very occasionally dose CMV cause aprimary infection in adults. most adult infections are caused by reactivation of the virus which was acquired early in life. an association exists between CMV and HIV
congenital infection are usually caused by reactivation of CMV during pregnancy and this rare because most people have been infected with the virus early in life. in developing countries . most congenital infection cause little or no harm to the infant. mostly as aresult of primary matrenal infection. CMV cause cytomegalic inclusion diseas in the newborn .the infant may be born with damage to the brain. jaundiced with an enlarged liver and spleen .
the patient with active CMV infections excrete the virus for long period in urine ,respiratory secretion , saliva ,semen, and from the cervix.the virus also found in white blood cell . CMV can usually be detected in fresh urine or saliva by electron microscope.

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Cytomegalovirus

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The most common types of infections by CMV can be group as follows:

• Fetus/Infant
  • Congenital CMV infection
  • Perinatal CMV infection
• Immunocompetent patient
  • CMV mononucleosis
  • Post-transfusion CMV - similar to CMV mononucleosis
• Immunocompromised patient
  • CMV pneumonitis
  • CMV GI disease
  • CMV retinitis

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معلومة وصلتنى ان معظم السيدات يوجد لديهم CMV IgG ايجابى ليس هو السبب الرئيسى فى الاجهاض ولكن ممكن ان يكون سبب من اسباب عديدة . بسبب وجود كثير من السيدات لديهم هذا الفيرس وينجبون اطفل اصحاء
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