Cytomegalovirus - What is It?

Cytomegalovirus - What is It?

All types of herpes are infections caused by viruses and have the common characteristic of being highly contagious and resistant. Once they become established in the body, they are permanent, except for the most severe type, herpes zoster. Symptoms usually disappear and reappear when the immune system is weakened, such as in times of stress. But it can also be symptomless, which makes it very difficult to diagnose. There are several types of herpes that infect humans, some more popular than others, but all are highly contagious. This article will explain the most important characteristics of one of the lesser-known viruses in this family: cytomegalovirus.


Cytomegalovirus

Cytomegalovirus is a virus among the herpesviridae family, and it is a DNA virus. In the general population, cytomegalovirus infection is highly prevalent and increases with age, infecting up to two-thirds of individuals and persisting latently in the host body indefinitely. While in the general population, this infection presents asymptomatically or minimally symptomatic in the form of a mononuclear syndrome. In the population of patients with a weakened immune system, cytomegalovirus infection can result in a wide range of clinical manifestations and organ involvement associated with significant morbidity and mortality. 


Once a person is infected, it remains latent in the body for life and can reactivate. It is very common, but most infected people are asymptomatic or have mild disease. It can cause serious problems in some particularly vulnerable groups: newborns who have been infected during pregnancy (congenital infection, which can cause deafness and neurological sequelae). It is a virus that is very important in transplant recipients, in whom it can cause serious symptoms and favor the rejection of the grafted organ, as well as in premature babies, as their immune system has not yet matured sufficiently.

Contagiousness of Cytomegalovirus

A girl unbuttons her pants in a contagious male sexually transmitted infection

It can be contracted through contact with body fluids such as saliva or urine. Other routes of transmission include blood, vaginal secretions and semen, breast milk, and through transplanted organs. Cytomegalovirus infection is common among infants and preschoolers. The virus is frequently transmitted within the family and in early childhood education centers. Another period of rapid acquisition is adolescence, of cytomegalovirus. Over half of the adult population has been infected with cytomegalovirus by the age of 40. Adults who have not had cytomegalovirus and who work with young children, especially children between 1 and 2.5 years of age, may be at higher risk of cytomegalovirus infection than people working in other settings.


Primary infection with cytomegalovirus spreads from the site of infection (skin or mucous membranes), where local replication occurs, to the vascular compartment (neutrophils and mononuclear leukocytes) and, from there, can infect almost all organs, mainly epithelial cells. Although the primary infection usually produces no symptoms (at most a mild Epstein-Barr virus mononucleosis-like syndrome in healthy people), cytomegalovirus enters a latent state which can reactivate and cause severe disease in severely depressed patients. The symptomatic disease occurs as a result of reactivation in the context of immunosuppression. Cytomegalovirus can infect almost all parts of the body and have the following manifestations.

Symptoms of Cytomegalovirus Disease

Cytomegalovirus infects humans.


In the majority of infections in adults who are not affected by cytomegalovirus, there are no symptoms. Sometimes, especially in children and adolescents, it causes a non-specific fever, as if it were a cold or flu, without the infected person knowing that they have been infected by this virus.

Occasionally, and especially if the infection occurs in adults, it manifests as a mononucleosis syndrome similar to infectious mononucleosis and consisting of:

-Fever.

-Enlarged lymph nodes and spleen (lymphadenopathy and splenomegaly). The lymph nodes and enlarged spleen are always smaller than in infectious mononucleosis virus infection.

-Hepatitis.

-Throat involvement in the form of pharyngitis is rare.

-Cytomegalovirus infection in immunosuppressed patients, i.e., patients with impaired defenses (transplant recipients, cancer patients, or AIDS patients), is very serious. 

-Congenital cytomegalovirus infection occurs in 0.5% of births and causes serious sequelae in the newborn, such as deafness or mental retardation. It is common for the child to be lost.


Treatment and Prevention

Valaciclovir pill of antiviral medication used to help reduce risk of infection

Valaciclovir pill of antiviral medication used to help reduce risk of infection.

With respect to congenital infection, antiviral therapy with ganciclovir has been shown to be effective in children with symptomatic infection in reducing the risk of long-term sequelae. There is insufficient evidence to recommend a particular measure in pregnant women to prevent transmission of cytomegalovirus to the fetus or sequelae of congenital infection. Education and behavior change (increased hand hygiene) may reduce the number of women with cytomegalovirus infections during pregnancy. Recent studies focus on passive immunization of pregnant women with immunoglobulins and antiviral treatment with valacyclovir to reduce the risk of congenital infection. 


There are two basic strategies to prevent cytomegalovirus disease in the transplant patient: universal prophylaxis and anticipatory therapy with monitoring of cytomegalovirus viremia in the recipient. Universal prophylaxis with ganciclovir, valganciclovir, or acyclovir reduces the risk of cytomegalovirus disease and mortality. Anticipatory therapy significantly reduces the risk of cytomegalovirus when compared to placebo or treatment of symptomatic disease. Although, there is no significant difference in the risk of cytomegalovirus disease or overall mortality when comparing universal prophylaxis and anticipatory therapy strategies. Differences have only been observed in leukopenia, which is much less frequent with anticipatory therapy.

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