Cytomegalovirus is an infectious agent and a cause of an infection which is basically well tolerated by healthy individuals. In healthy people the virus multiplies in the body, triggers certain symptoms and signs and infection soon gets under control. Certain people, however, may suffer great damage due to cytomegalovirus infection. This refers to pregnant women and immunocompromised patients. Contracting cytomegalovirus during pregnancy is highly detrimental for the fetus, associated with multiple organ damage while people with weakened immune system simply cannot fight off the infection and require aggressive treatment since the virus may be even a cause of lethal outcome.
Cytomegalovirus is a Worldwide Infection
CMV is actually a viral genus and it belongs to Herpesviridae family. The virus is also known under the name human CMV because this type affects humans only. According to certain characteristics and due to the fact that CMV and viruses such as HSV type 1 and 2, Varicella-zoster virus and Epstein-Barr virus belong to the same family but different subfamilies of Herpesviridae it is clear that the aforementioned viruses actually share some characteristics. For example, most of them remain in the body once the infection is gone. Since they are present in the body they may easily reactivate and trigger re-infection.
CMV infections affect people all over the world. The transmission is achieved via direct contact from an infected person to other people. The virus can be isolated from various bodily fluids including urine, blood, saliva, semen, cervical mucus and even breast milk. This drives to conclusion that there are different pathways of viral transmission. Hand-to-mouth contact with infected fluids is the most common one. However, the person may easily get infected via unprotected sexual contact, breastfeeding, blood transfusions and organ transplants. The virus passes through the placenta and easily infects the fetus.
As it has already been mentioned health individuals need not to worry about CMV but those with weak immune system as well as pregnant women are supposed to be aware of potential detrimental effects of the infection and try to at least prevent infection from developing. Impeccable personal hygiene, frequent and through hand washing and other such measures are highly efficient against infection.
When it comes to symptoms of CMV infection, the majority of patients have the infection without knowing it (asymptomatic disease). In case symptoms actually occur the affected individual develops fever, his/her lymph nodes become enlarged (usually glands in the neck) and there is a general feeling of not being well.
How does CMV Affect Pregnancy?
CMV is a major threat for each and every pregnant woman, to be more precise for her child since the woman may not even know she is infected while the virus can easily pass through the placenta and cause damage to her baby.
Fortunately the organization of Teratology Information Service (OTIS) estimated that the virus is transmitted in 30-50% cases meaning that not every fetus is affects. What is more, only 10-15% of infected babies actually show signs of congenital cytomegalovirus infection. Approximately 0.2-2.5% of babies all over the world are suffering from congenital CMV infection.
As for clinical presentation of congenital cytomegalovirus, it practically depends on whether the signs of infection are clear or not present at all (symptomatic/asymptomatic disease).
Cytomegalic inclusion disease is symptomatic form of the infection. This is the most severe infection caused by CMV virus and affects basically all the babies of pregnant women who have contracted the virus during their pregnancy. It is rarely reported in women in whom the primary viral infection took place before pregnancy while reactivation occurs during pregnancy. Cytomegalic inclusion disease almost always leads to intrauterine growth retardation, blood abnormalities, different skin problems such as petechiae and purpura as well as hepatosplenomegaly i.e. enlargement of the liver and spleen. The most detrimental effects are see in in the central nervous system. Microcephaly, ventriculomegaly and cerebral atrophy are awful health issues these babies are prone to. Furthermore, they may develop chorioretinitis and sensorineural hearing loss. One of the characteristics of CMV infection of this type are intracerebral calcifications that are easily confirmed with the assistance of CT scanning. The mentioned changes are blamed for cognitive deficits later in life. The neurodevelopmental prognosis of such patients is poor.
Asymptomatic congenital cytomegalovirus disease, on the other hand, affects fetuses of women who have preexisting immunity to CMV. The baby appears healthy at birth. There is usually subtle growth retardation and the child may easily suffer serious neurodevelopmental sequelae. Sensorineural hearing loss is the most reported complications of this type of CMV infection. It affects 15% of all infants and may be unilateral or bilateral. Hearing loss does not have to be detected at birth since many children become deaf months or even years after birth.
Finally, the baby may get infected prenatally, while passing down the birth canal or via breastfeeding. Prenatal infection is also either asymptomatic or the baby develops lymphadenomegaly, hepatitis and pneumonitis. The infection may be severe.