Cytomegalovirus (CMV) OverviewCytomegalovirus (CMV) is a common virus that infects people of all ages. It is a genus of Herpes viruses which is known as Human herpesvirus 5 (HHV-5) in humans. Cytomegalovirus is a member of Betaherpesvirinae in the subfamily Herpesviridae along with herpes simplex virus types 1 and 2, varicella-zoster virus (which causes chickenpox and shingles), and Epstein-Barr virus (which, together with CMV, are the main causes for infectious mononucleosis). These viruses share a characteristic ability to remain latent within the body over a long period. "Cytomegalovirus" means "very big cell virus". CMV can be spread by person to person contact (kissing, sexual contact, and getting saliva or urine on your, hands and then touching your eyes, or the inside of your nose or mouth), through the breast milk of an infected woman who is breast feeding, blood transfusions and solid organ transplantations, and also from am infected mother to her unborn child. CMV attacks the salivary glands, and can be fatal to fetuses. For persons with HIV or who have had an organ transplanted, CMV can be life threatening. CMV infection is thought to be specific to humans. The age at presentation, clinical manifestations, and route of infection may vary from person to person, but very few people escape infection during their lifetime. Serologic surveys conducted worldwide demonstrate CMV to be a ubiquitous infection of humans. Depending on the population surveyed, CMV may be found in 40-100% of people, depending on socioeconomic conditions. Infection earlier in life is typical in developing countries, whereas up to 50% of young adults are seronegative in many developed nations. CMV prevalence increases with age. Age has also been found to be a risk factor for CMV disease in certain transplant populations. SIGNS AND SYMPTOMS This virus usually produces few, if any, symptoms and it periodically reactivates without symptoms. Nevertheless, persons who have been infected with CMV develop antibodies to the virus, which persist in the blood of the individual for all his life. A person may be infected with CMV if he/she has symptoms of infectious mononucleosis (fever, fatigue, sore throat and swollen LYMPH NODES) but has negative test results for mononucleosis and Epstein Barr virus, or, shows signs of hepatitis, but has negative test results for hepatitis A, B, and C. Symptoms are present 9-60 days after primary infection. There are several types of CMV diseases: Congenital CMV disease is one of the TORCH infections (toxoplasmosis, other infections including syphilis, rubella, CMV, and herpes simplex virus) which may affect the development of newborns. Approximately 10% of congenitally infected infants have clinical evidence of disease at birth. The most severe form of congenital CMV infection is referred to as cytomegalic inclusion disease (CID). It almost always occurs in women who have primary CMV infection during pregnancy. The syndrome of congenital cytomegalic inclusion disease includes jaundice (yellowing of the skin and eyes), splenomegaly (enlarged spleen), thrombocytopenia (a low platelet count), intrauterine growth retardation, microcephaly (a condition, present at birth, in which the head is much smaller than normal for an infant of that age and gender), and retinitis (inflammation of the retina, the light-sensitive tissue at the back of the eyeball, that may lead to the loss of vision). Congenital CMV may also be asymptomatic. This happens when the mother has a preexisting immunity to CMV. These children appear normal at birth but they can have subtle growth retardation compared to uninfected children. The major consequence of asymptomatic CMV infection is the loss of hearing. Acquired CMV infection occurs postnatally. Primary infection is usually asymptomatic although CMV disease may occur in the following situations: - CMV mononucleosis. This is a disease of young adults which is acquired by person-to-person contact, by blood transfusions or solid organ transplantation. The symptoms include fever and severe malaise, the presence of an atypical lymphocytosis (increased numbers of circulating lymphocytes) and mild elevation of liver enzymes. - Transfusion-acquired CMV infection. Posttransfusion CMV infection has a presentation similar to that of CMV mononucleosis. Incubation periods range from 20-60 days. CMV infections in immunocompromised patients. Cytomegalovirus causes a variety of symptoms in immunocompromised patients. Disease manifestations vary in severity depending on the degree of host immunosuppression. Viral dissemination leads to multiple organ system involvement, with the most important clinical manifestations consisting of pneumonitis, gastrointestinal disease, and retinitis. There are several tests which help detect the presence of these antibodies and they are widely available from commercial laboratories. TREATMENT No treatment is generally necessary for CMV infection in the healthy individual since the majority of infections resolve on their own. For immunocompromised persons the treatment consists of antiviral agents: Ganciclovir (Cytovene), Cidofovir (Vistide), Foscarnet (Foscavir); immunoglobulins: Immune globulin intravenous (Gamimune, Gammagard, Sandoglobulin, Gammar-P), CMV-Ig (CytoGam), also a good nutrition. Vaccines are still in the research and development stage. PREVENTION Prevention is very important for pregnant or of childbearing age women. If you regularly come in contact with a large number of children, particularly in day care centre environments, you should avoid behaviours known to be associated with transmission of infection, particularly kissing and sharing eating utensils and carefully wash your hands after diaper changes. |