Cytomegalovirus infection igm and igg. What is a positive IGG to cytomegalovirus, what to do

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Material for research: Blood serum

Research method: Linked immunosorbent assay

Preparation: Blood from a vein can be donated after a 4-hour fasting period. The day before and on the day of blood donation, intensive physical activity, drinking alcohol, smoking. You can drink water.

Description:High quality and quantitation antibodiesIgMAndIgGto cytomegalovirus Cytomegalovirus infection – infection caused by herpes virus type 5 (cytomegalovirus). It is part of the group of infections of the TORCH complex, including rubella, toxoplasmosis, as well as pathology caused by herpes virus types 1 and 2. Infections included in the TORCH complex pose a serious threat to the health of the child, fetus, and patients with immunodeficiency. The virus is transmitted from a patient through close contact with biological fluids, sexual contact, transplacental from mother to fetus, during childbirth, breastfeeding. CMV is capable of infecting and damaging cells of various tissues and organs.

In persons with healthy immune system the disease is usually asymptomatic. The main manifestations include low-grade fever, headache, myalgia, pharyngitis. Symptoms of congenital infection are characterized by jaundice, pneumonia, enlarged liver and kidneys. There is hearing loss, vision pathology, mental retardation, severe violations CNS leading to microcephaly. To date serological diagnostics is the main tool for verifying and determining the stage of infection, including the determination of specific IgM and IgG antibodies, as well as the calculation of the avidity index for positive results of two classes of immunoglobulins.

Antibodies IgM class are the main indicator of how acute stage infections and reinfection/reactivation. It is important to consider that this class of antibodies can circulate in the body for more than a year. In some cases, false positives may be detected in uninfected subjects. IgM results. Thus, the study of IgM antibodies should be carried out exclusively in combination with other serological methods.

Antibodies of class G appear after IgM and remain in the body for a long time. They are detected during the acute, chronic and latent stages of infection. The detection of antibodies together with IgM, as well as a 4-fold increase in IgG concentration with an interval of 2 weeks, may indicate an acute stage of CMV infection. In these cases, to clarify the stage infectious process it is necessary to determine the antibody avidity index. The use of “direct” methods for detecting the virus, such as PCR, is also recommended.

Indications for the study:

examination of women planning pregnancy

pregnant women who do not have antibodies to CMV (every 3 months)

pregnant women with signs of current infection

immunodeficiency

patients with suspected acute CMV infection (picture infectious mononucleosis, prolonged low-grade fever, enlarged liver and spleen, pneumonia of unknown origin)

questionable result of the previous examination

Interpretation:

Reference values:

ResultIgM		Interpretation
Positivity index >1.0	"positively"	Presence of antibodies
Positivity index 0.8 – 1.0	"doubtful"	Zone of uncertainty
Positivity Index<0,8	"negative"	Absence of antibodies
ResultIgG		Interpretation
>0.25 IU/ml	"positively"	Presence of antibodies, quantity
0.2 – 0.25 IU/ml	"doubtful"	Zone of uncertainty
<0,2 МЕ/мл	"negative"	Absence of antibodies

IgG(-)IgM(-) - repeated testing is required during pregnancy (once every 3 months).

IgG(+)IgM(-) - immunity after past infection, no further testing required. If an active infection is suspected, re-send the sample after 10-14 days to monitor the IgG titer.

IgG(-)IgM(+) - retesting after 3 weeks to exclude a false positive result or the onset of an active infection.

IgG(+)IgM(+) - an acute stage of infection is possible, an avidity test is performed.

Doubtful - the result does not allow one to draw a conclusion about the presence or absence of antibodies; it is recommended to re-take the test after 14 days.

Antibodies to cytomegalovirus lgM, CMV IgM quantitative- allows you to determine the presence of IgM antibodies to cytomegalovirus (CMV or CMV).

When a person comes into contact with CMV, his immune system exhibits a protective response by producing IgM and IgG antibodies against CMV.

The duration of the incubation period is from 15 days to 3 months. With this infection, non-sterile immunity occurs (that is, complete elimination of the virus is not observed). Immunity to cytomegalovirus infection (CMV) is unstable and slow. Reinfection with an exogenous virus or reactivation of a latent infection is possible. Due to long-term persistence in the body, the virus affects all parts of the patient’s immune system. Specific antibodies are responsible for the lysis of the intracellular virus and also inhibit its intracellular replication or spread from cell to cell. Sera from patients after primary infection contain antibodies that react with internal proteins of CMV (p28, p65, p150). The serum of recovered people contains mainly antibodies that react with membrane glycoproteins.

The greatest diagnostic significance is the determination of IgM as an indicator of the activity of the process, which may indicate an acutely ongoing disease, reinfection, superinfection or reactivation. The appearance of anti-CMV IgM antibodies in a previously seronegative patient indicates a primary infection. During endogenous reactivation of an infection, IgM antibodies are formed irregularly (usually in fairly low concentrations) or may be completely absent. Detection of class G immunoglobulins also makes it possible to determine primary cytomegalovirus infection (CMVI), monitor over time individuals with clinical manifestations of infection, and help with retrospective diagnosis. In severe CMV disease, as well as in pregnant women and young children, the production of antibodies to CMV is slowed down. This is manifested by the detection of specific antibodies in low concentrations or the absence of positive dynamics of antibodies.

Cytomegalovirus infection is a widespread viral infection of the body, which belongs to the so-called opportunistic infections, which usually occur latently. Clinical manifestations are observed against the background of physiological immunodeficiency states (children in the first 3–5 years of life, pregnant women - more often in the 2nd and 3rd trimester), as well as in persons with congenital or acquired immunodeficiencies (HIV infection, use of immunosuppressants, oncohematological diseases, radiation, diabetes and so on.).

Cytomegalovirus- is part of the herpes virus family. Like other representatives of this group, it can persist in a person throughout his life. The risk group includes children 5–6 years old, adults 16–30 years old, as well as people who practice anal sex. Children are susceptible to airborne transmission from parents and other children with latent forms of infection. For adults, sexual transmission is more common. The virus is found in semen and other body fluids. Vertical transmission of infection (from mother to fetus) occurs transplacentally and during childbirth.

CMV infection is characterized by a variety of clinical manifestations. In healthy people with normal immunity, the primary infection occurs without complications (and is often asymptomatic). In rare cases, a picture of infectious mononucleosis develops (about 10% of all cases of infectious mononucleosis), clinically indistinguishable from mononucleosis caused by the Epstein-Barr virus. Replication of the virus occurs in the tissues of the reticuloendothelial system, epithelium of the urogenital tract, liver, mucous membrane of the respiratory tract and digestive tract. When immunity is reduced after organ transplantation, immunosuppressive therapy, HIV infection, as well as in newborns, CMV poses a serious threat, since the disease can affect any organ. The development of hepatitis, pneumonia, esophagitis, gastritis, colitis, retinitis, diffuse encephalopathy, fever, leukopenia is possible. The disease can be fatal.

Cytomegalovirus is dangerous in cases of immunodeficiency and during pregnancy is potentially dangerous for the development of the fetus. Therefore, 5–6 months before a planned pregnancy, it is necessary to undergo a TORCH examination in order to assess the state of immunity in relation to these viruses, if necessary, provide treatment, or provide prevention and control. When a pregnant woman is initially infected with cytomegalovirus (in 35–50% of cases) or the infection is reactivated during pregnancy (in 8–10% of cases), an intrauterine infection develops. If an intrauterine infection develops before 10 weeks, there is a risk of developmental defects and possible spontaneous termination of pregnancy. When infected at 11–28 weeks, intrauterine growth retardation and hypo- or dysplasia of internal organs occur. If infection occurs at a later stage, the damage may be generalized, affecting a specific organ (for example, fetal hepatitis) or appear after birth (hypertensive-hydrocephalic syndrome, hearing impairment, interstitial pneumonia, etc.). Manifestations of infection also depend on maternal immunity, virulence and localization of the virus.

To date, a vaccine against cytomegalovirus has not been developed. Drug therapy allows you to increase the period of remission and influence the recurrence of infection, but does not eliminate the virus from the body.

It is impossible to completely cure this disease: cytomegalovirus cannot be removed from the body. But if you promptly, at the slightest suspicion of infection with this virus, consult a doctor and carry out the necessary tests, then you can keep the infection in a “dormant” state for many years. This will ensure a normal pregnancy and the birth of a healthy child.

Laboratory diagnosis of cytomegalovirus infection is of particular importance in the following categories of subjects:

Women preparing for pregnancy

1. Latent course of the disease
2. Difficulty in differential diagnosis of primary infection and recurrent infection during examination during pregnancy
3. Severe consequences of intrauterine infection in newborns

Pregnant women

1. Severe consequences of intrauterine infection in newborns
2. Immunodeficiency states (generalized forms)

Consecutive repeated determination of the level of IgG antibodies in newborns makes it possible to distinguish congenital infection (constant level) from neonatal infection (increasing titers). If the titer of IgG antibodies does not increase during repeated (after two weeks) analysis, then there is no reason for alarm; if the titer of IgG increases, the issue of abortion should be considered.

СMV and TORCH
CMV infection is part of the group of TORCH infections (the name is formed by the initial letters in the Latin names - Toxoplasma, Rubella, Cytomegalovirus, Herpes), which are considered potentially dangerous for the development of a child. Ideally, a woman should consult a doctor and undergo laboratory testing for TORCH infection 2–3 months before a planned pregnancy, since in this case it will be possible to take appropriate therapeutic or preventive measures, and, if necessary, compare the results of studies before pregnancy in the future with the results of examinations during pregnancy.

Indications:

• preparation for pregnancy;
• signs of intrauterine infection, feto-placental insufficiency;
• state of immunosuppression due to HIV infection, neoplastic diseases, taking cytostatic drugs, etc.;
• clinical picture of infectious mononucleosis in the absence of infection caused by the Epstein-Barr virus;
• hepato-splenomegaly of unknown nature;
• fever of unknown etiology;
• increased levels of liver transaminases, gamma-GT, alkaline phosphatase in the absence of markers of viral hepatitis;
• atypical course of pneumonia in children;
• miscarriage (frozen pregnancy, recurrent miscarriages).

Preparation
It is recommended to donate blood in the morning, between 8 am and 12 pm. Blood is drawn on an empty stomach, after 4–6 hours of fasting. It is allowed to drink water without gas and sugar. On the eve of the examination, food overload should be avoided.

Interpretation of results


Units of measurement: UE*

A positive result will be accompanied by an additional comment indicating the sample positivity rate (SP*):

• CP >= 11.0 - positive;
• KP<= 9,0 - отрицательно;
• CP 9.0–11.0 - doubtful.

Important! To increase the information content of the research, an IgG antibody avidity study is performed as an additional test to clarify the likelihood of a recent primary infection.

Negative:

• CMV infection occurred more than 3–4 weeks ago;
• infection in the period 3–4 weeks before the examination is excluded;
• intrauterine infection is unlikely.

Positively:

• primary infection or reactivation of infection;
• intrauterine infection is possible.

"Doubtful"- a borderline value that does not allow reliably (with a probability of more than 95%) to classify the result as “Positive” or “Negative”. It should be borne in mind that such a result is possible with a very low level of antibodies, which can occur, in particular, in the initial period of the disease. Depending on the clinical situation, repeat testing of antibody levels after 10–14 days may be useful to assess changes.

*Positivity rate (PR) is the ratio of the optical density of the patient's sample to the threshold value. CP - positivity coefficient, is a universal indicator used in enzyme immunoassays. CP characterizes the degree of positivity of the test sample and can be useful to the doctor for the correct interpretation of the result obtained. Since the positivity rate does not correlate linearly with the concentration of antibodies in the sample, it is not recommended to use CP for dynamic monitoring of patients, including monitoring the effectiveness of treatment.

Cytomegalovirus IgG is positive - the result of a biochemical study that confirms the presence of this herpesvirus in the blood. In the vast majority of cases, the presence of pathogens in the body does not harm the health of an adult or child. But it is extremely, even deadly, dangerous for people with reduced immunity. Due to the weakening of the protective forces, cytomegaloviruses rapidly multiply and invade healthy tissues and organs.

In this article we will address the issue of IgG antibodies, which are produced in response to the introduction of cytomegalovirus into the human body.

Characteristic features of cytomegaloviruses

Cytomegalovirus is a genus of viruses from the Betaherpesvirinae subfamily of the Herpesviridae family. According to numerous studies, there are a huge number of virus carriers and people with a latent form of infection among the world’s population.

The fact of detection of serum IgG antibodies to cytomegaloviruses is recognized as evidence of human infection. This is an indicator that the human body has already encountered the pathogen. Most adults become infected with these members of the herpesvirus family during their lifetime, with 15% of cases occurring in childhood.

The penetration of cytomegaloviruses into the body does not go unnoticed by the immune system. It begins to intensively produce antibodies - high-molecular proteins immunoglobulins, or Ig. When they come into contact with viruses, antigen-antibody complexes are formed. In this form, infectious pathogens are easily vulnerable to T-lymphocytes - cells of the leukocyte blood unit responsible for the destruction of foreign proteins.

At the initial stage of immune defense, only IgM to cytomegalovirus is produced. They are designed to neutralize cytomegaloviruses directly in the blood. But these antibodies only reduce the activity of pathogens, so a certain amount of them manages to penetrate the cells. Then the production of IgM slows down and soon stops altogether. Only in cases of indolent chronic infection are these antibodies always present in the systemic circulation.

Soon the immune system begins to produce IgG antibodies. Immunoglobulins are involved in the process of destroying infectious agents. But after the virus is destroyed, they remain in the human blood forever. Antibodies G provide cellular and humoral immunity. If reintroduced, cytomegaloviruses will be quickly detected and destroyed immediately.

For 2-8 weeks after infection with cytomegalovirus, IgG and immunoglobulin A antibodies circulate in the blood simultaneously. Their main function is to prevent the adsorption of agents to the surface of cells of the human body. IgA ceases to be produced immediately after pathogens enter the intercellular space.

Who should be tested for CMV antibodies?

With a sharp decrease in immunity, cytomegalovirus (CMV) is activated, but this usually does not cause serious health problems in children and adults. Clinically, the infection is manifested by fever, weakness, malaise, headaches and joint pain, and runny nose. That is, it disguises itself as laryngitis, pharyngitis, and tonsillitis, which are widespread in childhood. Therefore, if a child has frequent colds, a test for the presence of IgG antibodies is required to determine further therapeutic tactics.

Biochemical analysis is also indicated in the following cases:

• pregnancy planning;
• identifying the causes of developmental disorders in newborns;
• assessment of the functioning of the immune system in patients with immunodeficiency conditions or malignant neoplasms;
• preparation for chemotherapy with drugs that suppress the immune system;
• planning to donate blood for transfusion to other people (donation).

An IgG test is also prescribed when symptoms characteristic of acute or chronic cytomegalovirus infection appear. So in men the testicles and prostate can be affected; in women, inflammation affects more the cervix and the inner layer of the uterus, vagina, and ovaries.

Detection method

IgG antibodies can be detected by performing an ELISA - enzyme-linked immunosorbent assay. The study is highly sensitive and informative. If IgG to cytomegalovirus circulates in a person’s blood, they will definitely be detected. The analysis also allows you to determine the form of infection and the stage of its course.

It is possible to detect IgM or IgG cytomegalovirus in the bloodstream in a laboratory setting in a relatively short time. The enzyme immunoassay is based on the antigen-antibody reaction. Venous blood serum is usually used as a biological sample. It is placed in eraser plates with several wells. Each of them contains a specific purified antigen to cytomegalovirus IgG and IgM antibodies.

A positive test result for IgG to cytomegalovirus means that the person is immune to this virus and is a carrier of it.

Moreover, this does not at all mean that the cytomegalovirus infection is in the active stage or any guaranteed dangers for a person - it all depends on his own physical condition and the strength of the immune system. The most pressing question of the presence or absence of immunity to cytomegalovirus is for pregnant women - it is on the developing fetus that the virus can have a very serious impact.

Let's look at the meaning of the analysis results in more detail...

IgG analysis for cytomegalovirus: the essence of the study

An IgG test for cytomegalovirus means looking for specific antibodies to the virus in various samples from the human body.

For reference: Ig is an abbreviation for the word “immunoglobulin” (in Latin). Immunoglobulin is a protective protein produced by the immune system to destroy the virus. For each new virus that enters the body, the immune system produces its own specific immunoglobulins, and in an adult, the variety of these substances becomes simply enormous. For simplicity, immunoglobulins are also called antibodies.

The letter G is a designation for one of the classes of immunoglobulins. In addition to IgG, humans also have immunoglobulins of classes A, M, D and E.

Obviously, if the body has not yet encountered the virus, then it has not yet produced the corresponding antibodies to it. And if there are antibodies to the virus in the body, and the test for them is positive, then, consequently, the virus has already entered the body at some point. Antibodies of the same class against different viruses are quite different from each other, so an IgG test gives a fairly accurate result.

An important feature of the cytomegalovirus itself is that once it infects the body, it remains in it forever. No medicine or therapy will help you get rid of it completely. But since the immune system develops a strong defense against it, the virus remains to exist in the body in an invisible and practically harmless form, persisting in the cells of the salivary glands, some blood cells and internal organs. Most carriers of the virus are not even aware of its existence in their bodies.

You also need to understand the differences between the two classes of immunoglobulins - G and M - from each other.

IgM are fast immunoglobulins. They are large in size and are produced by the body for the fastest possible response to the penetration of the virus. However, IgM does not form immunological memory, and therefore, with their death after 4-5 months (this is the lifespan of the average immunoglobulin molecule), the protection against the virus with their help disappears.

IgG are antibodies that, once produced, are cloned by the body and maintain immunity against a specific virus throughout life. They are much smaller than the previous ones, but are produced later on the basis of IgM, usually after the infection has been suppressed.

We can conclude: if cytomegalovirus-specific IgM is present in the blood, this means that the body became infected with this virus relatively recently and, perhaps, an exacerbation of the infection is currently occurring. Other details of the analysis can help clarify more subtle details.

Decoding of some additional data in the analysis results

In addition to just a positive IgG test, the test results may contain other data. The attending physician should understand and interpret them, but just to understand the situation it is useful to know the meanings of some of them:

1. Anti- Cytomegalovirus IgM+, Anti- Cytomegalovirus IgG-: cytomegalovirus-specific IgM is present in the body. The disease occurs in an acute stage; most likely, the infection was recent;
2. Anti- Cytomegalovirus IgM-, Anti- Cytomegalovirus IgG+: inactive stage of the disease. The infection occurred a long time ago, the body has developed a strong immunity, and viral particles that enter the body again are quickly eliminated;
3. Anti-Cytomegalovirus IgM-, Anti-Cytomegalovirus IgG-: There is no immunity to CMV infection. The organism had never encountered it before;
4. Anti- Cytomegalovirus IgM+, Anti- Cytomegalovirus IgG+: reactivation of the virus, exacerbation of infection;
5. Antibody avidity index below 50%: primary infection of the body;
6. Antibody avidity index above 60%: immunity to the virus, carriage or chronic form of infection;
7. Avidity index 50-60%: uncertain situation, the study must be repeated after a few weeks;
8. Avidity index 0 or negative: the body is not infected with cytomegalovirus.

It should be understood that the different situations described here may have different consequences for each patient. Accordingly, they require individual interpretation and approach to treatment.

A positive test for CMV infection in a person with normal immunity: you can just relax

In immunocompetent people who do not have diseases of the immune system, positive tests for antibodies to cytomegalovirus should not cause any alarm. Whatever the stage of the disease, with strong immunity it usually proceeds asymptomatically and unnoticed, only sometimes expressing itself in the form of a mononucleosis-like syndrome with fever, sore throat and malaise.

It is only important to understand that if tests indicate an active and acute phase of the infection, even without external symptoms, then from a purely ethical point of view, the patient needs to independently reduce social activity for a period of a week or two: be less in public, limit visits to relatives, not communicate with small children and especially with pregnant women (!). At this moment, the patient is an active spreader of the virus and is capable of infecting a person for whom CMV infection can be truly dangerous.

Presence of IgG in immunocompromised patients

Perhaps the most dangerous virus is cytomegalovirus for people with various forms of immunodeficiency: congenital, acquired, artificial. Their positive IgG test result may be a harbinger of complications of the infection such as:

• hepatitis and jaundice;
• cytomegalovirus pneumonia, which is the cause of death in more than 90% of AIDS patients in developed countries of the world;
• diseases of the digestive tract (inflammation, exacerbation of peptic ulcers, enteritis);
• encephalitis, accompanied by severe headaches, drowsiness and, in advanced conditions, paralysis;
• retinitis is an inflammation of the retina of the eye, leading to blindness in a fifth of patients with immunodeficiencies.

The presence of IgG to cytomegalovirus in these patients indicates a chronic course of the disease and the likelihood of an exacerbation with a generalized course of infection at any time.

Positive test results in pregnant women

In pregnant women, the results of an analysis for antibodies to cytomegalovirus can determine how likely the fetus is to be affected by the virus. Accordingly, it is based on the test results that the attending physician makes a decision on the use of certain therapeutic measures.

A positive test for IgM to cytomegalovirus in pregnant women indicates either a primary infection or a relapse of the disease. In any case, this is a rather unfavorable development of the situation.

If this situation is observed in the first 12 weeks of pregnancy, it is necessary to take urgent measures to combat the virus, since with primary infection of the mother there is a high risk of teratogenic effects of the virus on the fetus. With a relapse, the likelihood of fetal damage decreases, but still persists.

With later infection, it is possible for the child to develop a congenital cytomegalovirus infection or become infected at the time of birth. Accordingly, specific pregnancy management tactics will be developed in the future.

The doctor can determine whether the doctor is dealing with a primary infection or a relapse in this case by the presence of specific IgG. If the mother has them, it means that she has immunity to the virus, and the exacerbation of the infection is caused by a temporary weakening of the immune system. If there is no IgG for cytomegalovirus, this indicates that the mother became infected with the virus for the first time during pregnancy, and the fetus will most likely be affected by it, as well as the mother’s entire body.

To take specific therapeutic measures, it is necessary to study the patient’s medical history, taking into account many additional criteria and features of the situation. However, the mere presence of IgM already indicates that there is a risk to the fetus.

The presence of IgG in newborns: what does it mean?

The presence of IgG to cytomegalovirus in a newborn indicates that the baby was infected with the infection either before birth, or at the time of birth, or immediately after it.

Neonatal CMV infection is clearly indicated by a fourfold increase in IgG titer in two tests at a monthly interval. In addition, if the presence of specific IgG in the blood of a newborn is observed already in the first three days of life, they usually speak of a congenital cytomegalovirus infection.

CMV infection in children can be asymptomatic, or can be expressed by quite serious symptoms and have complications such as inflammation of the liver, chorioretinitis and subsequent strabismus and blindness, pneumonia, jaundice and the appearance of petechiae on the skin. Therefore, if cytomegalovirus is suspected in a newborn, the doctor must carefully monitor his condition and development, remaining ready to use the necessary means to prevent complications.

What to do if you test positive for antibodies to CMV infection

If you test positive for cytomegalovirus, you should first consult your doctor.

In most cases, the infection itself does not lead to any consequences, and therefore, in the absence of obvious health problems, it makes sense not to carry out treatment at all and entrust the fight against the virus to the body itself.

The drugs used to treat CMV infection have serious side effects, and therefore their use is prescribed only in cases of urgent need, usually in patients with immunodeficiencies. In these situations use:

1. Ganciclovir, which blocks the multiplication of the virus, but at the same time causes digestive and hematopoietic disorders;
2. Panavir in the form of injections, not recommended for use during pregnancy;
3. Foscarnet, which can cause kidney problems;
4. Immunoglobulins obtained from immunocompetent donors;
5. Interferons.

All these drugs should be used only on the recommendation of a doctor. In most cases, they are prescribed only to patients with immunodeficiencies or those who are prescribed chemotherapy or organ transplants that involve artificial suppression of the immune system. Only sometimes they treat pregnant women or infants.

In any case, it should be remembered that if previously there were no warnings about the danger of cytomegalovirus for the patient, then everything is fine with the immune system. And a positive test for cytomegalovirus in this case will only inform about the fact of the presence of already formed immunity. All that remains is to maintain this immunity.

Video about the danger of cytomegalovirus infection for pregnant women

Cytomegalovirus is a herpetic type microorganism that is opportunistic and latently lives in the bodies of 90% of people. When the immune system is weakened, it begins to actively multiply and leads to the development of infection. To diagnose the disease, an enzyme immunoassay for cytomegalovirus IgM is predominantly used - determining the presence of antibodies to the infectious agent in the blood.

Indications for the study

As a rule, cytomegalovirus does not pose a danger to a person with normal immunity and is asymptomatic; Sometimes mild symptoms of general intoxication of the body appear, which do not lead to the development of complications. However, for pregnant women and people with immunodeficiency, acute infection can be dangerous.

An enzyme immunoassay for antibodies to CMV is performed if the following symptoms are observed:

• increased body temperature;
• rhinitis;
• a sore throat;
• enlarged lymph nodes;
• inflammation and swelling of the salivary glands, in which the virus is concentrated;
• inflammation of the genital organs.

Most often, cytomegalovirus is difficult to distinguish from a common acute respiratory disease. It is worth noting that a pronounced manifestation of symptoms indicates a weakened immune system, so in this case you should additionally check for immunodeficiency.

The easiest way to distinguish cytomegalovirus from a cold is by the timing of the disease. Symptoms of acute respiratory infections disappear within a week; herpes infection can remain in acute form for 1–1.5 months.

Thus, the indications for prescribing the analysis are as follows:

1. Pregnancy.
2. Immunodeficiency (caused by HIV infection, taking immunosuppressants, or congenital).
3. The presence of the above symptoms in a person with normal immunity (the disease must first be differentiated from the Epstein-Barr virus).
4. Suspicion of CMV in a newborn child.

Given the possible asymptomatic course of the disease, during pregnancy the test should be performed not only in the presence of symptoms, but also for screening.

The immune system first responds to the entry of any foreign microorganisms into the blood by producing antibodies. Antibodies are immunoglobulins, large protein molecules with a complex structure that are able to bind to proteins that make up the shell of viruses and bacteria (they are called antigens). All immunoglobulins are divided into several classes (IgA, IgM, IgG, etc.), each of which performs its own function in the body’s natural defense system.

IgM class immunoglobulins are antibodies that are the first protective barrier against any infection. They are produced urgently when the CMV virus enters the body, do not have a specification and have a short lifespan - up to 4–5 months (although residual proteins that have a low coefficient of binding to antigens may remain 1–2 years after infection).

Thus, an analysis for IgM immunoglobulins allows you to determine:

• primary infection with cytomegalovirus (in this case, the concentration of antibodies in the blood is maximum);
• exacerbation of the disease - the concentration of IgM increases in response to a sharp increase in the number of viral microorganisms;
• reinfection - infection with a new strain of the virus.

Based on the remnants of IgM molecules, over time, IgG immunoglobulins are formed, which have a specification - they “remember” the structure of a particular virus, persist throughout life and do not allow the infection to develop unless the overall strength of the immune system is reduced. Unlike IgM, IgG antibodies against different viruses have clear differences, so analysis for them gives a more accurate result - they can be used to determine which virus has infected the body, while analysis for IgM only provides confirmation of the presence of infection in a general sense.

IgG antibodies are very important in the fight against cytomegalovirus, since it is impossible to completely destroy it with the help of medications. After the exacerbation of the infection ends, a small number of microorganisms remain in the salivary glands, on the mucous membranes, and internal organs, which is why they can be detected in samples of biological fluids using polymerase chain reaction (PCR). The virus population is controlled precisely by IgG immunoglobulins, which prevent cytomegaly from becoming acute.

Decoding the results

Thus, enzyme immunoassay makes it possible to accurately determine not only the presence of cytomegalovirus, but also the period elapsed since infection. It is important to evaluate the presence of both major types of immunoglobulins, so IgM and IgG antibodies are considered together.

The results of the study are interpreted as follows:

IgM	IgG	Meaning
–	–	A person has never encountered cytomegalovirus, so the immune system is “not familiar” with it. Considering that almost all people are infected with it, the situation is very rare.
–	+	Normal for most people. This means that there was contact with the virus in the past, and the body has developed a permanent defense against it.
+	–	Acute primary infection - the infection occurred recently, “fast” immunoglobulins were activated, but there is no permanent protection against CMV yet.
+	+	Exacerbation of chronic infection. Both types of antibodies are activated when the body has encountered the virus previously and has developed permanent protection, but it does not cope with its task. Such indicators indicate a serious weakening of the immune system.

Particular attention should be paid to a positive IgM antibody result in pregnant women. If IgG immunoglobulins are present, there is nothing to worry about; acute infection poses a danger to the development of the fetus. Complications in this case occur in 75% of cases.

In addition to the actual presence of antibodies, enzyme immunoassay evaluates the avidity coefficient of proteins - their ability to bind to antigens, which decreases as they are destroyed.

The results of the avidity study are deciphered as follows:

• >60% - immunity to cytomegalovirus is developed, infectious agents are present in the body, that is, the disease occurs in a chronic form;
• 30–60% - relapse of the disease, an immune response to the activation of a virus that was previously in a latent form;
• <30% - первичное инфицирование, острая форма заболевания;
• 0% - no immunity, there was no CMV infection, there are no pathogens in the body.

It should be borne in mind that a person with a strong immune system does not need to worry about positive test results - cytomegalovirus does not require drug treatment, the body is quite capable of coping with the infection on its own. However, if the results indicate an acute phase of the disease, you should limit contact with healthy people, especially pregnant women, as there is a high probability of spreading the virus.

Positive IgM result during pregnancy

For women planning a pregnancy or already carrying a child, it is very important to know about a past infection with cytomegalovirus, as this can affect the development of the fetus. An enzyme immunoassay for antibodies comes to the rescue with this.

Test results during pregnancy are assessed differently. The safest option is positive IgG and negative IgM - there is nothing to worry about, since the woman has immunity against the virus, which will be passed on to the child, and there will be no complications. The risk is also small if positive IgM is detected - this indicates a secondary infection that the body is able to fight, and there will be no serious complications for the fetus.

If no antibodies of either class are detected, the pregnant woman should be very careful. It is important to follow measures to prevent infection with cytomegalovirus:

• avoid sexual intercourse without using contraception;
• avoid sharing saliva with other people - do not kiss, do not share dishes, toothbrushes, etc.;
• maintain hygiene, especially when playing with children, who, if they are infected with cytomegalovirus, are almost always carriers of the virus, since their immunity is not yet fully formed;
• See a doctor and get tested for IgM for any manifestations of cytomegalovirus.

It is important to remember that it is much easier to become infected with the virus during pregnancy due to the fact that a woman’s immunity naturally weakens during pregnancy. This is a mechanism of protection against rejection of the embryo by the body. Like other latent viruses, old cytomegalovirus can become active during pregnancy; this, however, only in 2% of cases leads to infection of the fetus.

If the result for IgM antibodies is positive and for IgG antibodies is negative, the situation is most dangerous during pregnancy. The virus can enter the fetus and infect it, after which the development of the infection may vary depending on the individual characteristics of the child. Sometimes the disease is asymptomatic, and permanent immunity against CMV develops after birth; in 10% of cases, the complication is various pathologies of the development of the nervous or excretory system.

Particularly dangerous is infection with cytomegalovirus during pregnancy of less than 12 weeks - an underdeveloped fetus cannot resist the disease, which leads to miscarriage in 15% of cases.

An IgM antibody test only helps determine the presence of the disease; The risk to the child is assessed through additional tests. Based on a number of factors, appropriate pregnancy management tactics are developed to help minimize the likelihood of complications and congenital defects in the child.

Positive result in a child

An embryo can become infected with cytomegalovirus in several ways:

• through sperm during fertilization of the egg;
• through the placenta;
• through the amniotic membrane;
• during childbirth.

If the mother has IgG antibodies, then the child will also have them until about 1 year of age - initially they are there, since during pregnancy the fetus shares a common circulatory system with the mother, then it is supplied with breast milk. As breastfeeding stops, the immune system weakens and the child becomes susceptible to infection from adults.

Positive IgM in a newborn indicates that the child was infected after birth, but the mother does not have antibodies to the infection. If CVM is suspected, not only an enzyme-linked immunosorbent assay is performed, but also PCR.

If the child’s body’s own defenses are not enough to fight the infection, complications may develop:

• slowdown in physical development;
• jaundice;
• hypertrophy of internal organs;
• various inflammations (pneumonia, hepatitis);
• lesions of the central nervous system - mental retardation, hydrocephalus, encephalitis, problems with hearing and vision.

Thus, the child should be treated if IgM antibodies are detected in the absence of IgG immunoglobulins inherited from the mother. Otherwise, the body of a newborn with normal immunity will cope with the infection on its own. Exceptions are children with serious oncological or immunological diseases, the course of which may affect the functioning of the immune system.

What to do if the result is positive?

A person’s body with a healthy immune system is able to cope with the infection on its own, so if an immune response to cytomegalovirus infection is detected, nothing can be done. Treatment of a virus that does not manifest itself in any way will only lead to a weakening of the immune system. Medicines are prescribed only if the infectious agent begins to actively develop due to an insufficient response of the body.

Treatment is also not necessary during pregnancy if there are IgG antibodies. If only the IgM test is positive, medication is necessary, but it is intended to contain the acute infection and convert the cytomegalovirus into a latent form. It should be remembered that medications for CMV are also unsafe for the body, so they can only be used if prescribed by a doctor - self-medication will lead to various adverse consequences.

Thus, positive IgM indicates an active stage of CMV infection. It should be considered in conjunction with other test results. Particular attention to the test indications should be paid to pregnant women and people with weakened immune systems.