The herpes viruses are an extremely well-known family of viruses.

Everyone is familiar with the classic cold sore, or the disease chickenpox, which occurs mainly in children, and its sequelae, shingles.

The human cytomegalovirus (human herpesvirus 5) also belongs to the herpes viruses.
It is an enveloped, double-stranded DNA virus that has a typical, very large cell nucleus.

The membrane envelope of human herpes virus 5 is extremely sensitive, which is why the virus has only a very short survival time outside of a host. In general, the virus has a very narrow host spectrum and is very sensitive to various solvents and acids.

The virus also has a very slow reproduction cycle, but once it appears in the body, it never completely disappears, just like all other herpes viruses.

Course and consequences of an infection with a human cytomegalovirus:

If you become infected with the human herpes virus 5, you will contract cytomegaly as a result. After infection, the first symptoms appear after an incubation period of about four to six weeks.

In healthy and immunocompetent persons, 99% of cases have a very mild course with few to no symptoms. Symptoms that can typically occur are prolonged fever (the body temperature is strongly elevated for weeks) and increased liver values.

In a mild course, which occurs in almost all cases, no antiviral medication is necessary. If complications occur, such as thrombocytopenia (lack of platelets in the blood), myocarditis (inflammation of the heart muscle) or pneumonia (inflammation of the lungs), treatment becomes absolutely necessary. However, severe complications are unlikely in immunocompetent individuals and are more likely to occur in immunocompromised patients.

Consequences of infection in immunocompromised patients:

As harmless as the virus is for immunocompetent persons, it can develop dangerously in immunocompromised patients.

If the immune system does not have the strength to fight the virus, the human herpes virus 5 can multiply unhindered and cause severe damage. A new infection, but also a reactivation of the virus can thus become extremely dangerous.

Acute, but also chronic inflammations can develop in the large intestine, often in connection with diarrhoea. The diarrhoea causes the body to lose a lot of fluid and also to absorb too few nutrients, which further weakens the immune system.

Patients who have a kidney transplant can also face severe consequences if the human herpes virus 5 reactivates. The virus attacks the transplant, which can lead to a significant deterioration in function; in the worst case, the patient may even lose the donor organ.

AIDS is one of the best-known diseases that attack the human immune system. If the disease breaks out, immunosuppression occurs, making the patient extremely susceptible to illness. Even a cold can have many times the effect of a healthy person because of the weakened immune system.

Similarly, an infection with the human herpes virus 5 is extremely dangerous for AIDS patients. If an infection occurs, the patient must receive a highly active antigen medication, otherwise the virus will attack the retina. If the human herpes virus 5 is able to multiply unhindered, it settles in the retina and destroys it, leading to blindness in the patient. If the infection remains untreated in an AIDS patient, there is a 30% risk of a retinal infection.

Infection with human herpes virus 5 during pregnancy:

If the infection occurs before pregnancy, antibodies have already formed in the blood, so there is no risk to the child. However, if the initial infection occurs during pregnancy, this can have serious consequences for the child, especially if it occurs in the first trimester.

If the mother becomes infected during the first months of pregnancy, there is a 20% chance that the infection will be passed on to the child. Especially in the first trimester, the foetus is extremely sensitive, which can lead to secondary damage if the foetus is infected. If the child is infected in the womb, there is a 50% risk of permanent secondary damage.
Hearing impairment has been found to be a particularly frequent sequelae, but also microcephaly, growth retardation and mental retardation, as well as neurological late effects.

If the mother is infected in the last trimester of pregnancy, there is an extremely high risk that the child will also be infected (80%). Since the foetus (especially the brain) is already very developed at this point, the consequences are not as drastic as in the first trimester. So far, no disease has been found that is connected with an infection at this time.

Why does human herpes virus 5 belong to the oncoviruses?

In healthy people, the virus does not normally cause any problems, but immunocompromised people can suffer from secondary diseases, including chronic hepatitis, which can lead to liver carcinoma.

Transmission of the human herpes virus 5:

The virus is transmitted via blood, saliva, urine and sperm secretion.

It should be noted, however, that a herpes virus can only be transmitted when it is active, i.e. directly after the initial infection, or during reactivation. During the resting phases, the virus is "asleep", so there is no risk of infection.

Since the virus has only a very short survival period without a host, direct contact is necessary for infection. To transmit the virus via saliva, for example, a kiss, or during sexual intercourse via the sperm secretion. Infection via the blood is rare, but also possible.

Even though the virus has a very short life span outside the host, and the possibility of infection is also very clearly defined, the rate of infection is very high (between 30% and 90%).

The reason for this is the mostly asymptomatic course. If an infection is clearly visible, one can take measures oneself and others can also protect themselves from the infection. If an infection is not visible, one then passes on the virus without being aware of contamination.

What protective measures can I take?

At the current state of research, there is still no vaccination against the virus, and it is also difficult to protect oneself against infection, as the disease usually causes no to very few symptoms. If you work in a high-risk occupational group (in the medical field), you should make sure that you do not come into direct contact with body fluids if you are pregnant.