Cytomegalovirus

Content

Introduction

Cytomegalovirus (CMV) is a virus belonging to the herpesvirus family, extremely common and easily transmitted.

It has been calculated that the infection affects 60/90% of the world population. In Italy, according to blood tests, over 80% of people have a "CMV infection contracted in the past.

The infection is difficult to detect because in most cases it causes ailments similar to influenza or infectious mononucleosis or does not cause any at all.

The body's defense system (immune system), in fact, is able to effectively and quickly control the reproduction of the virus, preventing it from spreading in the body.

Like most herpesviruses, CMV is able to remain in the body's cells without manifesting itself and reactivated following the weakening of the immune system or in the case of psycho-physical stress (secondary infection).

The virus can create significant health problems in children under the age of 2 and in people with a weakened defense system following chronic diseases or infections such as HIV / AIDS.

The virus during pregnancy can be passed on to the baby and cause a severe infection present at birth (congenital). In Italy, according to different epidemiological studies, this occurs in a very limited number of cases.

CMV can also cause pregnancy loss under certain circumstances.

Symptoms

CMV infection is generally contracted during childhood, adolescence or, more rarely, in adulthood.

Often it does not cause any disturbances (symptoms) and you do not notice that you have been infected by it. In cases where fever, malaise, sore throat or swollen lymph nodes appear, the infection is often confused with the flu or infectious mononucleosis and, consequently, laboratory tests are hardly carried out to ascertain it.

Disorders (symptoms) generally last 5-10 days, but in early childhood or in the case of a weakened immune system, they may remain longer.

CMV infections that develop in people with AIDS or severe cancer can affect all organs and, in particular, cause pneumonia with impaired respiratory function, retinitis with impaired vision, or encephalitis.

CMV infection present at birth (congenital) manifests itself in a very variable manner: in some cases it does not cause significant disturbances while in the most serious cases it can cause severe impairment of liver function (with the presence of red spots on the skin and yellow of the eyes and skin), of the lungs (with difficulty in breathing and possible insufficiency of the amount of oxygen needed by the body tissues) and of the central nervous system with delayed development of the body and mind, convulsions, blindness and deafness.

These manifestations vary from case to case and can be temporary or persist for a long time, with the risk of disability or life-threatening complications.

Causes

CMV is a very widespread virus and almost the entire population comes into contact with it at some stage of life.

During the first (primary) infection, the virus can spread to all parts of the body and be present in biological fluids such as saliva, mucus, urine and genital secretions.

Contagion generally occurs following close contact with the person carrying the infection, mainly through the inhalation / ingestion of droplets of saliva or mucus from the respiratory tract, more rarely through contact with urine (children).

Sexual transmission cannot be ruled out even if most adults are already protected against the virus thanks to their immune system. The infection can be transmitted, finally, following a transfusion of blood / blood products or organ transplantation from donors in which it has not been possible to verify the presence.

In most cases the person who has an ongoing "CMV infection is not aware of it because, usually, no disturbances appear.

In cases of severe depression of the body's defense system (immune) caused by chronic diseases, tumors (leukemia), infections (HIV / AIDS) or drugs (immuno-suppressive) there is an increased susceptibility to CMV infection which, under these circumstances, it can lead to damage to many organs and serious health problems.

Transmission of the virus from mother to child is possible during pregnancy, at delivery or during breastfeeding.

Diagnosis

The ascertainment (diagnosis) of a possible CMV infection generally requires the execution of blood tests since, not causing specific disorders, it is not easily identifiable during the medical examination.

With laboratory analyzes it is possible to detect in the blood the presence of so-called anti-CMV antibodies which, in the case of an infection in the past, are of the IgG class while, in the case of ongoing infection, they are of the IgM class.

The suspicion of the presence of a CMV infection transmitted from mother to child should lead to the search, during pregnancy or at birth, for viral genetic material in the amniotic fluid (by amniocentesis) or in the blood and secretions of the newborn.

In people with severe impairment of the immune system, or in the case of infection present at birth (congenital), damage to the retina and brain can be highlighted with appropriate instrumental investigations.

Therapy

In cases of infection that causes mild ailments, adequate rest is sufficient with the possible help of anti-inflammatory drugs.

Specific treatment (therapy) against CMV is needed only in the most serious situations, mainly in people with weakened immune systems due to AIDS, immunosuppressive therapies after a transplant, blood / lymphatic system cancers and in the case of newborns , in which the infection causes damage to organs.

There are drugs effective against CMV, capable of specifically interfering with a herpesvirus protein (polymerase), which must be administered either generally or locally under the adequate supervision of a specialist doctor.

Prevention

Prevention of CMV infection is extremely difficult due to the widespread prevalence of the infection among the population and the fact that, in cases with no or few disorders, the infection is not ascertained (diagnosed).

As with most respiratory-borne viral infections, the practice of adequate hygiene standards and rest at home, especially if fever is present, can help limit the transmission of CMV, particularly among children.

In the case of severe weakness of the body's defense system following AIDS, organ transplants or cancers of the blood / lymphatic system, preventive treatment (prophylaxis) with specific drugs against CMV or specific antibodies may be required.

This treatment is indicated in women who contract the infection during pregnancy to prevent its transmission to the baby.

There is currently no vaccine approved for preventive or therapeutic use, but trials are underway with vaccines that could provide appreciable protection against CMV infection.

The availability of an effective vaccine could allow, within a few years, to limit the circulation of the virus among the population, reducing the likelihood of congenital infections and serious consequences in people with inefficient immune systems.

Living with

CMV infection is acquired mainly in the first 30 years of life and, often manifesting itself in a mild form and without disturbances, it is not a major health problem.

It is always advisable for children with fevers of unknown cause to temporarily avoid attending schools and places of aggregation.

On the other hand, it is essential to prevent and treat the infection quickly in cases of severe impairment of the immune system (people with AIDS or cancers of the blood and immune cells, people undergoing organ transplants or immunosuppressive treatments) and in confirmed cases of infection already present at birth (congenital) if major disorders or organ damage are present.

It is advisable that all pregnant women carry out tests to exclude, even in the absence of disorders, an "ongoing CMV infection in order to prevent transmission to the fetus or child.

Bibliography

EpiCentro (ISS). Cytomegalovirus

Centers for Disease Control and Prevention (CDC). Cytomegalovirus (CMV) and congenital CMV infections (English)

National system for guidelines (SNLG). Physiological pregnancy

Griffiths P, Lumley S. Cytomegalovirus [Summary]. Current Opinion in Infectious Diseases. 2014; 27: 554-9

Luisi K, Sharma M, Yu D. Development of a vaccine against cytomegalovirus infection and disease [Summary]. Current Opinion in Virology. 2017; 23: 23-29

Rawlinson WD, Hamilton ST, van Zuylen WJ.Update on treatment of cytomegalovirus infection in pregnancy and of the newborn with congenital cytomegalovirus [Summary]. Current Opinion in Infectious Diseases. 2016; 29: 615-624

In-depth link

Ministry of Health and Italian Society of Infectious and Tropical Diseases. Italian guidelines on the use of antiretroviral drugs and on the diagnostic-clinical management of people with HIV-1 infection

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