Toxoplasmosis: transcript analysis. Diagnosis of Toxoplasmosis

Not everyone knows that they are carriers of an infection such as toxoplasmosis. This disease rarely causes severe symptoms, so a person does not even suspect infection. But is toxoplasmosis so harmless? In the world, cases of the development of serious complications after infection of the disease are recorded. Infection during pregnancy is extremely dangerous. Therefore, in some cases, it is important to undergo a timely examination for toxoplasmosis. Deciphering the tests for this infection requires special medical knowledge. We will try to clarify the essence of the main modern methods of diagnosing the disease, tell us what their advantages and disadvantages are, help to decipher the results.

Toxoplasmosis - what is it?

In order to understand the essence of methods for the diagnosis of toxoplasmosis, it is important to understand what this disease is. So, toxoplasmosis is an infectious disease caused by the parasite Toxoplazma gondii. Carriers of oocysts (spores of parasites) are cats. But other animals can become intermediate hosts. With mammalian excrement, toxoplasmosis spores enter the soil. Therefore, you can become infected if you do not comply with hygiene standards during contact with animals, eating raw meat, unwashed vegetables and fruits. Infection also occurs in utero - from the infected mother to the fetus.

The disease is tolerated once, after which the body develops stable immunity in the form of antibodies, thereby protecting a person from reinfection with a disease such as toxoplasmosis. Decryption of analyzes is carried out taking into account this particularity of the body.

What is dangerous toxoplasmosis?

In most cases, toxoplasmosis does not cause severe symptoms and complications in an adult with a normal immune response. But in people with reduced body defenses, disturbances in the functioning of the nervous system, fever, enlarged liver, and eye damage can occur.

Toxoplasmosis infection is especially dangerous during pregnancy. Infection penetrates the fetus and infects it. The medical prognosis in this case is unfavorable - a miscarriage, premature birth, stillbirth are possible. In the case of a successful delivery, the child may have congenital disorders of the nervous system, serious damage to internal organs, often incompatible with life. In connection with such a high level of danger for the normal course of pregnancy and the development of the fetus during the period of conception planning, as well as throughout the entire period of gestation, a woman is assigned laboratory tests to determine the acute phase of the disease, namely the primary infection. Decryption of the analysis for toxoplasmosis during pregnancy should be carried out only by a specialist and taking into account all factors affecting the study.

Methods for diagnosing infection

Diagnostic methods of toxoplasmosis can be divided into 3 large groups:

1. Serological studies are based on the detection of antibodies to infection in biological material that are produced in the body immediately after infection. The advantage of this examination is the ability to identify a quantitative indicator of antibodies, which helps to determine the duration of infection, thereby highlighting the acute period of a disease such as toxoplasmosis. Decryption of this type of analysis is carried out by determining the quantitative detection of IgG and IgM immunoglobulin proteins. The disadvantage of this type of diagnosis is the lack of information for HIV-positive people, since in their body the immune system is weakened and produces antibodies to infections only in small quantities.
2. Parasitic are based on the detection in the blood of parasites - the causative agents of toxoplasmosis. A significant drawback of this type of diagnosis is the inability to determine the duration of infection, and accordingly, the acute phase of the disease cannot be distinguished. The interpretation of the analysis for toxoplasmosis in this case occurs when the parasite is directly detected in the test material.
3. Hardware is used as an additional means of making or refuting the diagnosis of toxoplasmosis in cases difficult from the point of view of diagnostic medicine.
   

More often than other methods, a blood test for toxoplasmosis is used. Deciphering the results is usually not difficult and is carried out by the serological method.

Serological diagnostic methods

The following diagnostic methods are used to determine antibodies to toxoplasmosis:

1. RIF, or immunofluorescence reaction , is carried out in this way: using special chemical reagents, the material is diluted. In a special microscope that displays ultraviolet light, antibodies will be visible. In the presence of toxoplasmosis, the glow will be bright - this result is displayed in the form: +++ or ++++.
2. RNG, or an indirect hemagglutination reaction , is based on the property of red blood cells to precipitate during certain chemical reactions. If, after carrying out the necessary laboratory procedures, red blood cells have covered the bottom of the tube, the result is positive. It is designated as follows: “intense reaction +++” and “sharply intense reaction ++++”.
3. ELISA, or an enzyme-linked immunosorbent assay , is used to determine toxoplasmosis more often than others, as it has several advantages: it is carried out quickly, using special equipment, has the ability to trace the dynamics, as well as analyze 2 types of immunoglobulins IgG and IgM. To conduct such an analysis, test systems manufactured in the Czech Republic and Finland are used. Such tests can be successfully performed for all groups of subjects, including HIV-infected people.

Decoding analysis for toxoplasmosis by ELISA

In order to correctly decipher the results of the analysis for toxoplasmosis by the ELISA method, one should understand the essence of biological infection processes. Antibodies of the protein groups of immunoglobulins of the IgG and IgM type are produced by the body to combat the pathogen and protect against secondary infection. IgM antibodies are produced by the body immediately after infection with toxoplasmosis, are in the body for up to a month, after which the indicators gradually decrease and completely disappear. Thus, the detection of IgM antibodies in the analysis is a sign of an acute form of toxoplasmosis.

IgG type immunoglobulins begin to be produced in the body on the 3rd day of infection and protect a person from reinfection with toxoplasmosis throughout life. Thus, the detection of antibodies of this group and the lack of IgM indicators suggests that the body is protected, therefore there is no reason for concern. But there are other options for the results of the analysis for toxoplasmosis by ELISA. Then the interpretation of the analysis for toxoplasmosis requires additional examinations to confirm the acute form of the disease or the absence thereof. The options indicated in the table are possible.

Analyzing the table, it can be noted that it is difficult to identify acute toxoplasmosis. IgG is positive - the transcript of the analysis can indicate both a previous infection and a primary infection. But the presence of IgM antibodies usually indicates an acute stage of the disease.

Torch infections during pregnancy

During pregnancy planning and in the early stages of gestation, doctors prescribe a comprehensive analysis, which has the abbreviation TORCH. Studies are being conducted on infections that are transmitted in utero and cause serious impairment of fetal development. Such diseases include toxoplasmosis, rubella, cytomegalovirus, herpes simplex, syphilis. The analysis is carried out by a serological research method, namely ELISA. The decoding of the results of the analysis for torch infection is also carried out according to the ELISA method described in the table.

Parasitic diagnostic methods

The presence or absence of parasites - the causative agents of toxoplasmosis - is determined using microscopy of the material (blood, saliva, tissue samples during a biopsy). This method is uninformative: it does not have the ability to track the process in dynamics and determine the duration of infection.

To date, they use this type of parasitic method for the diagnosis of toxoplasmosis, as polymerase chain reaction. Using this study, parasite DNA is isolated. In this way, you can detect the pathogen even with a small quantitative ratio of it in the material. But decoding the result of a blood test for toxoplasmosis using the PCR method does not make it possible to determine the duration of infection and to track the dynamics of the disease. Doctors prescribe this method as an additional study in the presence of controversial results of serological tests, in particular, the diagnosis of ELISA, as well as the impossibility of other methods of detecting toxoplasmosis in a specific clinical case. Often used the PCR method to determine toxoplasmosis in children of the first year of life and AIDS patients, when the time factor is not a priority.

Using this diagnostic method, it is not difficult for a doctor to determine the diagnosis of toxoplasmosis — deciphering the tests is not difficult. So, a positive result indicates the presence of a parasite in the test material, a negative one indicates its absence.

Conducting parasitic methods for the diagnosis of toxoplasmosis has a number of features: firstly, there is a possibility of a false negative result due to the fact that the parasites have already settled in the tissues of the organs and are not in a specific area of ​​the studied material. And secondly, pathogens, if all the necessary conditions are not met, can die in the material taken for analysis even before microscopy, which will also negatively affect the result of the study.

Diagnosis of intrauterine toxoplasmosis

When confirming infection of a pregnant woman, the question arises of intrauterine infection of the fetus - additional diagnostics are necessary. The interpretation of the tests for toxoplasmosis by intrauterine methods is based on the detection of fetal development pathologies, as well as the direct determination of parasites in the amniotic fluid. There are such methods of intrauterine examination of toxoplasmosis:

1. Ultrasound diagnostics - allows you to identify abnormalities in the development of the fetus, namely such violations as a decrease in the thickness of the placenta, the detection of calcifications in the tissues of the brain of the fetus, ascites and hepatomegaly, which may indicate the penetration of the pathogen from the mother to the fetus.
2. Amniocentesis, or the study of amniotic fluid, is carried out by PCR diagnostics of toxoplasmosis.

Diagnostic methods in complicated medical cases

With complicated forms of infection or the inability to use common diagnostic methods for toxoplasmosis, the following methods for detecting the disease are used:

1. Subcutaneous test with toxoplasmin. The drug is injected. Evaluate the result after two days. If there is swelling, the diameter of which is at least 10 mm, then the sample is considered positive. Such an analysis does not answer the question of whether the disease is acute or if there is a long-standing infection.
2. Instrumental methods help to identify specific disorders and deviations in the work of internal organs, characteristic of a parasite lesion - the causative agent of toxoplasmosis. Apply methods such as ultrasound, computed tomography, nuclear magnetic resonance, biopsy. Only the specialist can decrypt the result of such diagnostic procedures.
   

In most cases, doctors prescribe a standard blood test for toxoplasmosis. Decryption is carried out by ELISA or PCR. In controversial cases, additional tests and examinations are recommended. Often, for the correct interpretation of the results, it is necessary to take into account a whole range of medical factors that affect the final diagnosis. Therefore, do not unravel the results yourself, but seek qualified help from a specialist.