Cytomegalovirus infection
Cytomegalovirus infection is not of particular concern when contracted by healthy adults or children in good health. However, it is very feared during pregnancy, especially if it involves a woman for the first time during pregnancy: in this case the virus can infect the fetus and cause very serious damage.
Fortunately, only a minority of women who acquire Cytomegalovirus during pregnancy, and even fewer of those who reactivate during this period, transmit the infection to the product of conception. In statistical terms, there is considerable variability of data in the scientific documents consulted, for which - as an identifier - we report those disseminated by the higher institute of health:
- The risk of transmission to the fetus varies between 30 and 40% in the primary form and between 0.5 and 2% in the secondary form.
- 85-90% of newborns with congenital infection are asymptomatic. About 10% of asymptomatic newborns present late sequelae, generally hearing defects of variable severity, with possible fluctuating or progressive courses.
- About 10-15% of newborns are symptomatic, with symptoms that may be temporary or permanent; of these 10-30% will go against a perinatal death and 70-90% in neurological sequelae.
The main concerns are the cases in which the mother contracts the infection for the first time in the period between the two months preceding conception and the first three of the pregnancy, while the primary infection during the second and third trimester of gestation is progressively less severe.
A possible secondary or recurrent infection in an already infected pregnant woman is less worrying: since together with the virus the mother also transmits the antibodies to the fetus to eradicate it, the lower the percentages of fetuses affected and the less the seriousness of the distance sequelae with respect to what happens in case of primary infections with Cytomegalovirus. The latter, in fact, especially if contracted during the first trimester of gestation, often involve important manifestations: growth retardation, prematurity, hearing damage, hepatosplenomegaly, jaundice and permanent neurological damage up to perinatal mortality.
| Congenital infection with symptomatic cytomegalovirus: typical symptoms | Congenital cytomegalovirus infection: sequelae (Remington 2006) | ||||||||||||||||||||||||||||||
petechiae / purpura (75-100%) hepatosplenomegaly (75-100%) CNS involvement (70%): - Microcephaly (87%) - brain calcifications (80%) -meningoencefalite (75%) jaundice (50-75%) prematurity SGA (20-50%) hypotonia, lethargy, sucking difficulties, convulsions, defect of tooth enamel |
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Diagnosis
SEARCH FOR ANTI-CYTOMEGALOVIRUS ANTICORES IN PREGNANCY
It is sufficient to undergo a simple blood test to identify an infection that is present or past due to Cytomegalovirus.
On the blood sample taken from the patient, the analysis laboratory will assess the presence of specific antibodies, directed against the microorganism: if these are present the patient is defined as seropositive, vice versa seronegative if they are absent. In particular, anti-Cytomegalovirus antibodies of IgG and IgM calms are dosed: the IgM antibody positivity is spy of a recent infection, while that of IgG antibodies indicates a previous contact with the virus without providing useful information on the period of infection. Some more information comes from a more detailed examination, called IgG avidity test, which allows us to go back to the period of infection. Low IgG avidity (0.8) indicates the absence of a current or recent primary infection.
Unfortunately, as regards IgM, the risk of false positives has been demonstrated, therefore to appear recently infected with Cytomegalovirus (for the positivity to IgM) despite the infection is non-existent. Slight increases in IgM are recorded even at a short distance (1-2 months) from the reactivation phases.
When to do the exam and how to interpret the results
Whenever possible, it is a good idea to have a blood test for anti-Cytomegalovirus antibodies every month starting from two months before conception until the first 3-4 months of pregnancy, to check for infections during this period.The most suitable time to undergo these tests is of course the preconception period.
In the event that the IgG dosage is negative before pregnancy, particular attention is required to the mother to follow preventive measures useful to avoid primary infection. At the same time, the woman will be subjected to periodic monitoring to ascertain the absence of IgM positivization, which would indicate a Cytomegalovirus infection contracted during gestation. If this eventuality occurs, to determine the possible transmission of the virus to the fetus (which as we have seen occurs between 30 and 40% of cases), more detailed examinations are necessary, such as amniocentesis.
Conversely, in the case of positive IgG, the woman has already had the infection; therefore, she can face pregnancy with greater serenity. However, it should be stressed that prevention plays a crucial role even for positive IgG women. Recently, in fact, it has been shown that during pregnancy women already immune before conception can be re-infected with an antegenically different strain of Cytomegalovirus, so that the disease can be transmitted to the fetus with symptomatic manifestations, just as if it were of a primary infection.
MOLECULAR DIAGNOSIS
Some limitations of tests conducted for the detection of anti-Cytomegalovirus antibodies in pregnancy are now overcome by modern techniques of gene amplification, which allow the qualitative and quantitative detection of the virus directly from a blood or urine sample.
This technique is also performed on the sample of amniotic fluid taken through amniocentesis for the prenatal diagnosis of the infection.
Prevention
To prevent infection with Cytomegalovirus during pregnancy, it is advisable to avoid all occasions when the woman can come into contact with the mucous membranes of infected people or their body fluids. Particularly at risk are the children of preschool age (especially under the age of three-five years), who often contract infection in nursery schools and kindergartens, being highly infectious even when they do not show any symptoms of infection.
- wash your hands thoroughly and often with soap and water, especially if the woman comes into contact with small children (<3-5 years). The greatest risk of infection is when the woman kisses an infected child, or brings her hands to her nose, eyes or mouth, after feeding, bathing, cleaning her nose, or changing her diapers to a child or touched his toys. For good hand washing see this article.
- do not share plates, glasses, toothbrushes, towels, cutlery, glasses, with small children (do not suck the baby's pacifier to clean it)
- keep toys, rattles and anything that may be dirty with saliva or urine from small children.
Care and Treatment
At the present state of science, neither vaccines nor drugs against Cytomegalovirus that can be used in pregnancy yet exist. The research for the production of a vaccine against Cytomegalovirus is however intense and rather promising experimental results have already been obtained.
Although the currently available antiviral medicines cannot be used during gestation, they can still be administered to the newborn in case of confirmed infection. Among these we mention the Ganciclovir, to be administered intravenously in doses of 6 mg / kg to be repeated twice a day for six weeks. As an alternative to Ganciclovir, it has been proposed to administer a prodrug derived from it, Valganciclovir, which can be taken orally in doses of 16 mg / kg to be repeated twice a day for six weeks. The same drugs can also be used by immunocompromised patients affected by a primary or secondary, symptomatic and complicated infection with Cytomegalovirus.
