Inclusion body disease, salivary gland virus diseaseCytomegaly is an infectious disease caused by a specific virus, namely Human Herpesvirus 5 (also “Human Cytomegalovirus“). Cytomegaly occurs worldwide only in humans. In the western industrial nations, the virus (cytomegaly) can be found in about 40% of adults, in developing countries the infection is even greater at almost 100%.
Most people become infected during childhood and then carry the virus (cytomegaly) unnoticed. The human herpes virus 5 (cytomegaly), discovered in the 1950s, belongs to the large family of herpesviridae. A total of 8 different viruses are distinguished here, each of which causes specific clinical pictures.
Common to all Herpesviridae is that they can remain passively in the body of the affected patient for the rest of his or her life after an infection. Depending on the body cells in which the virus dwells, a distinction is made between 3 subfamilies of herpes viruses, namely alpha, beta and gamma herpes viruses. The cytomegalovirus belongs to the beta subfamily, which means that it survives in so-called lymphocytes and granulocytes, which are special cells of the immune defence.
The virus (cytomegaly) multiplies only very slowly, and the affected cells of the affected organism are also destroyed very slowly. The human herpes virus 5 (cytomegaly) is transmitted through saliva and other body fluids in close physical contact, for example during kissing or sexual intercourse. In addition, an unborn child can be infected via the placenta if the mother has a high number of viruses in her blood.
Viruses can also be transmitted from mother to child during birth or breastfeeding. Transfusions with infected blood are also a natural source of infection (cytomegaly). About 90% of all infections (cytomegaly) are asymptomatic.
This means that although the person affected carries the virus, does not develop any signs of illness and actually feels healthy, the immune system keeps the virus under control here. In some (rather rare) cases, however, symptoms may develop after an incubation period (i.e. the time between infection with the virus and the first appearance of symptoms) of 2-6 weeks. In addition to a general feeling of illness and discomfort, fever and swelling of the lymph nodes can occur, as well as headaches and aching limbs.
Overall, the course of cytomegaly is rather harmless in otherwise healthy people, but it is feared that on the one hand an infection of an unborn child in the womb and on the other hand an infection of patients who have an insufficiently functioning immune system. If a pregnant woman becomes infected with the virus (cytomegaly) for the first time in the first or second third of pregnancy, the infection is transmitted to the unborn child in about 40% of cases and can lead to malformations in the unborn child; in the worst case, such an infection can even result in the death of the unborn fetus in the womb. However, if a woman has already been infected with the virus once in her life and now falls ill again, the risk of transmission to the unborn child is much lower at around 1%.
In total, 5-10 infected children per 1000 live births are assumed, and 10% of these infected children again show signs of disease during birth (cytomegaly). Any malformations mainly affect the cardiovascular system and the gastrointestinal tract; for a few weeks or months these malformations can manifest themselves as hearing damage, seizures, motor disorders, an enlarged liver and spleen, and inflammation of the choroid or the retina of the eye. Furthermore, the occurrence of petechiae, i.e. very small bleedings from the vessels into the skin, which appear as red spots and do not disappear when pressure is applied to the skin, has been observed.
These bleedings into the skin are due to a pathologically increased bleeding tendency caused by the virus (cytomegaly). Suspected CMV infections during pregnancy are flu-like signs of illness in the mother. However, since the symptoms are so similar to those of influenza, cytomegaly is often not recognized.
The second group of patients at risk besides pregnant women consists – as described above – of people with a weakened immune system. These can be patients who have just had an organ transplant and in whom the immune system is specifically suppressed by certain drugs so that the body does not reject the foreign organ. AIDS patients also have an immune system that does not function well.
In this case, the HI virus attacks the body’s own immune cells directly, making the patients very susceptible to what are actually harmless diseases. If the immune system does not function sufficiently, infection with the cytomegalovirus often leads to inflammation of the entire body, very often severe pneumonia. If a patient’s clinical picture gives rise to suspicion of infection with the cytomegalovirus, the diagnosis can be made by means of various laboratory tests and examinations.
In this context, the direct detection of antibodies against the virus in the patient’s blood is particularly important. Antibodies are special proteins that are produced by the defence cells of the affected organism to inactivate the virus. In addition to the detection of antibodies, direct virus isolation also plays a role in diagnostics (cytomegaly)Typical for an infection with the cytomegalovirus are so-called “owl eye cells”, i.e. endogenous cells that change when infected with the virus in such a way that they look like large owl eyes under the microscope.
This characteristic feature of the virus is also described by its name: the Greek terms “kytos” = cell and “megalo” = large form the term cytomegaly. In the case of a mild form of cytomegaly in an otherwise healthy person, it is usually quite sufficient to take symptomatic action against the signs of the disease (e.g. lowering fever) and not to attack the virus itself. However, in immunocompromised people, therapy with the drug acyclovir is often advisable.
Aciclovir is a drug that can be administered locally as an ointment, as a tablet or intravenously and stops the virus multiplying in the body. This works because acyclovir is very similar to a certain component of viral DNA (the nucleic base guanine). This DNA building block, guanine, is normally activated by a specific viral enzyme and then incorporated into the DNA of the virus so that it can multiply.
However, if acyclovir is also present in the body, it is activated by the viral enzyme because of its great similarity to guanine. The unactivated guanine cannot be used and the viruses cannot multiply. Aciclovir should not be used during pregnancy, but on the whole it does not have many side effects.
Unfortunately, the viruses are becoming increasingly resistant to acyclovir, which is why in some cases the active substance ganciclovir is also used to treat cytomegaly. Ganciclovir is structurally related to acyclovir and is also similar to the DNA building block guanine; the mechanism of action is the same. Ganciclovir unfortunately has a higher rate of side effects than acyclovir.
Among other things, it can lead to disturbances of the blood count with a reduced platelet count, in addition, complaints in the area of the gastrointestinal tract and central nervous disorders such as headaches, dizziness and hallucinations are possible side effects. Unfortunately, no effective vaccination against the cytomegalovirus is yet available, although various vaccines are currently being developed. Women who are planning to become pregnant can be tested for the presence of antibodies against the virus in the body, but this is not yet an integral part of antenatal care and is not covered by health insurance (the cost is about 13 euros).
If there are no antibodies against the virus, there is always the risk of infection with the virus during pregnancy. In such a case a control examination is recommended in the 20th to 24th week of pregnancy. If there is then contact with the virus (cytomegaly), antibodies against the virus can be administered passively, although it is not certain whether the unborn child is also completely protected in this way. Before a planned pregnancy, it is always advisable to check the partner for cytomegalovirus, as transmission to the pregnant woman can occur particularly quickly.
