Anti-Toxo-IgM (IgM class antibodies to Toxoplasma gondii). How to decipher a test for toxoplasmosis: main indicators Toxoplasmosis deciphering test results Helix
Let's look at widely used tests for toxoplasmosis, when the patient simply donates blood in the laboratory. And the first of them is PCR.
PCR
If class M antibodies are found in the blood of a pregnant woman and class G antibodies gradually increase, which will be discussed below, then this indicates a primary infection, a fresh process. It is in this case that even if the woman feels normal, she needs to be treated urgently to prevent infection of the fetus and the occurrence of congenital deformities.
Also, the detection of these immunoglobulins allows us to make a diagnosis of acute toxoplasmosis in newborns. The fact is that class G immunoglobulins are common in both mother and baby.
Therefore, when they are detected in a child, he himself may be healthy, but the antibodies came to him from a mother who had been ill, and even recovered. But class M immunoglobulins cannot pass through the placenta, and therefore, if they are found in the child’s blood, the analysis indicates that he is sick with toxoplasmosis and received it in utero. Detection of class M immunoglobulins in a baby allows not only to make an early diagnosis, but also to begin urgent treatment, even in the case of a low antibody titer.
Antibodies class G to Toxoplasma
We have already said enough about pregnant women; a blood test for toxoplasmosis is mandatory for them, and more than once. But in what cases should a test for toxoplasmosis be prescribed to other categories of the population? What are the indications for prescribing PCR and immunoglobulin testing for toxoplasmosis?
Indications for blood tests
In addition to testing pregnant women, as well as women wishing to become pregnant, screening for toxoplasmosis is required for the following categories of the population:
- enlargement of the liver and spleen of unknown origin, or hepatosplenomegaly syndrome;
- prolonged and unclear fever;
- acquired immunodeficiency, as well as HIV infection;
- chronic damage to muscle tissue, or myositis (after all, toxoplasmosis can affect muscles);
- Lymphadenopathy (enlarged lymph nodes), including generalized, in the absence of other causes;
- recurrent miscarriage (this is a separate case);
- severe neurological diseases such as encephalitis, in the absence of other causes.
Finally, a blood test for toxoplasmosis should be taken from those family members who have all of the conditions described above, or simply chronic infections, fever and malaise if there are cats in the house.
How to donate blood for toxoplasmosis?
In order to donate blood for toxoplasmosis, no special preparations are needed. Regular venous blood is donated, which is taken from the cubital vein. The analysis must be carried out in the morning on an empty stomach, and on the eve of the analysis it is advisable to limit physical activity, not drink alcoholic beverages, and it is advisable not to smoke at least an hour before blood sampling. No other special preparations are required.
Test results
How can one interpret the results of all the analyzes mentioned above?
PCR
If we are talking about antibodies, or immunoglobulins, then they have their own norm in the blood, or titer. If the patient has class M immunoglobulins, then the threshold value is considered to be 1.1 c.u. (conventional unit). Above and inclusive of this value, specific antibodies are considered to have been detected.
If the patient's antibody titer is less than 0.9 arbitrary units, then there are no antibodies. Of course, this range is too narrow. But here we have to rely on additional information from the anamnesis. In the case of positive values, we can talk about either an acute infection or an indefinite period of infection (up to a year), as well as congenital toxoplasmosis, but only if the study was done in the first weeks of the baby’s life. If class M immunoglobulins for toxoplasma are not detected, then this may indicate not only that the person is healthy, but also that he is sick, only the duration of the disease is insignificant, for example, less than 3 weeks, and antibodies of this class simply did not have time to develop.
Class G immunoglobulins have slightly different reference values. If the plasma level is 1.6 c.u. or less, then the conclusion is “negative”. More than 3 USD e - “positive”.
If the patient's blood serum contains more than 3 u. e, including with repeated studies, this indicates activation of the infection and its spread in the body, and a decrease in antibody titer indicates, for example, successful treatment.
What can a doctor conclude in case of negative values? Firstly, that a person is healthy if he has a negative PCR test and immunoglobulin M. Secondly, a patient with a toxoplasmosis infection may simply have a very weak immune system, which prevents the production of normal antibodies. And, as in the previous case, we can talk about an acute infection - up to two weeks after infection.
Toxoplasmosis is a serious infection. It should be remembered that, along with cytomegalovirus and rubella, it is part of the so-called group, which is especially dangerous for pregnant women and for the development of the child. This means that a consultation and laboratory examination for this group of infections must be done 3 months before the planned pregnancy, because if anything is revealed, it will be possible to take measures for diagnosis and treatment, and prevent infection of the unborn baby.
Tests for toxoplasmosis are important laboratory tests that help identify the pathogen in the human body.
Causes, symptoms and routes of transmission of the disease
Toxoplasma pathogens most often enter the human body through unwashed vegetables and fruits, raw meat and after contact with cats. Infection can occur after the bite of an insect vector or from mother to fetus through the umbilical cord.
The symptoms of toxoplasmosis are similar to some other diseases, so a person most often learns about the disease after recovery.
The main symptoms include the following factors:
- high body temperature;
- pain in joints and muscles;
- severe headaches;
- rapid fatigue and weakness of the limbs;
- apathy.
Very often, the chronic form of acquired toxoplasmosis is accompanied by an increase in the size of some lymph nodes, lack of sleep, decreased appetite and hallucinations.
The congenital disease is characterized by various skin rashes, enlarged spleen, decreased vision, yellowing of mucous membranes and sometimes death.
Diagnosis of toxoplasmosis
Most often, the disease passes without significant symptoms, so to find out about the presence of oocysts in the body, you need to be tested for toxoplasmosis. It also allows you to find out about the time of infection and the developed immunity to the pathogen. How is a blood test done for toxoplasmosis? To do this, you first need to contact an infectious disease specialist. After a complete examination, you may need the help of a neurologist or ophthalmologist.
The test for toxoplasmosis does not require special preparation. But before the procedure you should still follow a few recommendations:
- Stop taking any antibacterial drugs two weeks before the test;
- For an accurate diagnosis, it is not recommended to eat fatty, spicy, sour or smoked foods within a couple of days. Caffeine-containing drinks and alcohol are excluded from the daily diet;
- The evening before the test, you should not use shower gels, various creams or talcum powders: blood for toxoplasmosis is taken from a vein, and scented products can affect the results;
- You need to take the test for toxoplasmosis on an empty stomach.
Modern laboratory research methods consist of two diagnostic methods.
1 way
Using an enzyme-linked immunosorbent assay (ELISA), you can determine the presence of immunoglobulins in the blood serum that appear in the body in response to a pathogen.
Early immunoglobulins or lgM are produced immediately after oocysts enter the body and disappear within a few weeks. Late immunoglobulin (lgG) appears after thirty days and remains in the body throughout life, developing immunity to relapse.
Method 2
The polymerase chain reaction method detects the DNA of the pathogen in the human body. This test for toxoplasmosis is considered an accurate laboratory test, but due to high costs it is carried out if confirmed by ELISA.
To clarify the diagnosis, only blood serum is used. The patient’s urine and feces are not suitable for laboratory research, since the pathogen does not undergo sexual development in his body.
The doctor gives a referral for testing only if infection is suspected. Pregnant women undergo this procedure in the early stages. If the diagnosis is confirmed, a repeat test is scheduled after a few weeks.
Interpretation of analyzes
The analysis required requires decoding: even minor knowledge about the disease allows you to decipher it yourself. But only a highly qualified specialist can see small changes in the blood.
How is the test for toxoplasmosis deciphered?
After passing the ELISA test in the laboratory, the number of immunoglobulins is calculated, on which four variants of the development of the disease depend:
| Immunoglobulins lgM | Immunoglobulins IgG | Decryption result |
| No | No | The patient had never suffered from toxoplasmosis. Pregnant women are at risk, so donating blood to detect infection is necessary throughout the nine months. |
| No | Yes | It is necessary to conduct tests for antibody avidity and PCR diagnostics. If avidity is high and the polymerase chain reaction gives a negative result, it means that the patient has suffered from the infection for a long time, and the body has developed a strong immunity against the pathogen. |
| Yes | No | These indicators indicate the acute course of the disease. Additionally, avidity analysis and PCR are performed. |
| Yes | Yes | The presence of two immunoglobulins at once indicates a primary infection. Additional tests and procedures are required. |
Some test results for toxoplasmosis require additional procedures when deciphered. Avidity allows us to determine how actively immunoglobulins bind to Toxoplasma.
Avidity has three options:
- Indicator up to 40 units: The infection occurred approximately three days ago and is acute. For pregnant women, this is a high chance of infecting the fetus, so visiting a doctor should not be delayed;
- Indicator 41-59 units: infection is in a transition phase. The tests should be repeated in two weeks;
- Indicator over 60 units: the body has developed a strong immunity to the pathogen, the risk of re-infection is eliminated.
Deciphering the analysis for toxoplasmosis using PCR diagnostics has two options: the presence of pathogen DNA in the blood indicates an acute course of the disease, and its absence excludes the presence of toxoplasma in the body.
There is no exact treatment regimen for the infection: therapy depends on the degree of the disease and the general condition of the patient. With strong immunity, there is practically no treatment: the patient can only be prescribed vitamins. A severe form of the disease requires complex therapy, which includes taking antibiotics, vitamins, pathogenetic agents and immunomodulators. If the case is advanced, the attending physician may prescribe the patient a course of chemotherapy.
It is impossible to cure toxoplasmosis with the help of traditional medicine. But it will be an excellent addition to drug therapy.
After consultation with specialists, you can use garlic infusion, pumpkin seeds and horseradish.
Consequences of toxoplasmosis
In a person with a strong immune system, the disease passes in a short time without any symptoms and does not have serious consequences. Otherwise, the infection can cause damage to the nervous system, retina, problems with the endocrine and respiratory systems.
Pregnant women are at risk, so when examining them, special attention is paid to the necessary tests. Infection with toxoplasmosis in the early stages can lead to spontaneous miscarriage, premature birth or failure to develop the fetus in the womb. Very often, a child is born with disorders of the nervous system, problems with vision, liver and brain.
Tests for toxoplasmosis, like any research, can detect diseases in the early stages and help to carry out therapy correctly. To prevent infection, experts recommend following personal hygiene rules, washing food well and processing meat. If you wish, you can contact an infectious disease specialist who will tell you in detail about toxoplasmosis and tell you how to take tests to identify the pathogen.
What tests are used to diagnose toxoplasmosis?
Diagnosis of toxoplasmosis is carried out taking into account the patient’s medical history and laboratory results. Various serological methods are used as laboratory tests to detect the presence of specific immunoglobulins (IgM and IgG classes) for Toxoplasma. A blood test for toxoplasmosis can be performed using one or more methods from the list below.
- Enzyme-linked immunosorbent test (ELISA);
- Indirect (passive) hemagglutination reaction (IRHA/RPHA);
- Immunofluorescence analysis (IFA);
Upon contact with Toxoplasma, the human body produces specific protein compounds (immunoglobulins, also called “antibodies”) that are active against one or another harmful form of life. Toxoplasmosis produces IgM and IgG antibodies.
Note. A general blood test for toxoplasmosis is not very informative and does not reveal the disease. With toxoplasmosis, specific changes occur in the blood, which, taking into account the medical history, suggest the presence of infection. One of these indicators is an increased number of lymphocytes in the blood. With toxoplasmosis, relative lymphocytosis is recorded (over 35%). The norm of lymphocytes varies between 19-37%.
There are no specific restrictions when donating blood or urine. Blood for toxoplasmosis is taken from the ulnar vein, urine for testing is collected in the morning (morning portion). If it is impossible to draw blood from the ulnar vein, sampling is done from other venous vessels (for example, from the back of the hands or feet).
However, compliance with basic restrictions before donating blood is the key to the quality of the serum. 24 hours before the procedure for collecting venous blood, you should minimize the consumption of meat products and fatty foods, and absolutely eliminate alcoholic beverages. It is also necessary to exclude the use of medications that thin the blood, as this increases the breakdown of red blood cells and the release of hemoglobin. Such blood is not suitable for research. Half an hour before donating blood, you must stop smoking.
As for urine, the procedure is also standard and does not require a special approach. After getting up in the morning, we carry out hygienic procedures for the genitals, take a clean container prepared in advance, empty 1/3 of the bladder into the toilet, then fill the container with the required volume, and empty the rest into the toilet.
IgM antibodies are fairly large immunoglobulins and appear first in toxoplasmosis. Promote the activation of phagocytosis and have an effect on gram-positive bacteria. The normal rate varies from 0.4 to 2.6 units. A decrease in this indicator indicates suppressed humoral immunity due to chronic viral infection and other pathological processes that contribute to immune depletion.
The breakdown of the blood test for toxoplasmosis is as follows:
It should be understood that serological research methods are highly sensitive and accurate, however, false-positive and false-negative results may well occur.
Note. False-negative and false-positive ELISA results are extremely rare, however, small deviations from the real picture occur in ¼ of cases.
A key component of accuracy when conducting a study is a specialist, since the identification and determination of immunoglobulins depends on his experience and skills. Violation of the requirements for collecting biological material can also cause inaccurate results.
The presence of any rheumatic diseases in the patient should be disclosed to the attending physician before blood sampling. Metabolic disorders are another reason for the increased likelihood of receiving inaccurate data.
Failure to comply with the established restrictions before donating blood also increases the risk of obtaining inadequate data. This is especially true when taking medications. Long-term use of medications can significantly affect the accuracy of the result.
Conclusion
Since about a third of the adult population of the entire world had contact with Toxoplasma and in most cases did not have any consequences or manifestations of the disease, we can safely say that toxoplasmosis is not a dangerous disease for a person who has a normal immune system.
Toxoplasmosis is extremely dangerous during pregnancy, so it is wise to conduct a blood test for toxoplasmosis when planning a pregnancy.
The test for toxoplasmosis is included in the complex of tests for TORCH infections, which all pregnant women undergo. The disease is practically asymptomatic. But the presence of this disease in a pregnant woman can lead to severe pathologies of fetal development.
Toxoplasmosis
During pregnancy, it is extremely important to get tested for toxoplasmosis. An infected pregnant woman is at risk of spontaneous abortion. The probability of fetal infection does not exceed 15%. But if a woman is infected in the first trimester of pregnancy, the risk of chorioretinitis (inflammation of the retina and choroid) and severe neurological defects in the child increases significantly. Congenital toxoplasmosis often leads to generalized lesions in newborns. If a pregnant woman becomes infected with toxoplasmosis in the third trimester, the likelihood of infection of the fetus increases to 65%.
In adults with normal immunity, this disease is asymptomatic. With a decrease in the body's defenses, toxoplasmosis can manifest itself in chronic (mild), subacute and acute (severe) forms. The main symptoms of toxoplasmosis are headache, myalgia (muscle pain), fever, lymphadenopathy (enlarged lymph nodes). This infection can affect any organs and systems of the body.
Indications for analysis
This disease is diagnosed using a laboratory test of the patient's blood.
Indications for prescribing a blood test for toxoplasmosis:
- control examination in women before and during pregnancy;
- lymphadenopathy in a pregnant woman, if testing for toxoplasmosis has not previously been carried out;
- immunodeficiency states;
- HIV infection;
- hepatosplenomegaly of unknown origin;
- lymphadenopathy of unknown origin;
- fever of unknown origin;
- re-examination after receiving a questionable test result for toxoplasmosis during pregnancy.
Types of analyzes
The main methods of blood testing for toxoplasmosis are the following:
- enzyme-linked immunosorbent assay (ELISA) - blood test for IgG and IgM antibodies;
- PCR diagnostics (polymerase chain reaction method).
The blood test method for IgG and IgM antibodies (enzyme immunoassay) is based on the determination of antibodies against Toxoplasma antigens.
Toxoplasma, like all microorganisms, consists of complex organic substances called antigens. When antigens enter the blood, the cells of the human immune system perceive them as foreign and begin to produce immunoglobulins - antibodies - against them. In this case, antibodies accumulate in human blood in certain concentrations (titers).
Immunoglobulins G and M differ from each other. Thus, IgM immunoglobulins are produced by the human immune system in the first days of infection. The amount of these antibodies reaches its maximum level at 2–3 weeks of illness, then after 1–2 months they disappear. Therefore, the presence of these immunoglobulins in the analysis for toxoplasmosis indicates the acute phase of the disease.
IgG antibodies begin to be produced by the immune system 2-3 days later than IgM antibodies. The maximum amount of these immunoglobulins occurs a month after the onset of the disease. IgG antibodies do not disappear from the blood, but remain in it for a long time, for many people - for life. Thanks to this, a person develops specific immunity against toxoplasmosis, and the disease does not occur during re-infection. If IgG antibodies are detected in the test results during pregnancy, you don’t have to worry about the baby’s health.
Analysis transcript
Different laboratories use different methods of analysis, so the values of normal and elevated titers differ in different laboratories. Usually, in the analysis results form issued, next to each indicator, the normal value is indicated, when compared with which you can see whether the antibody titer detected in the patient is decreased or increased.
If the titer of IgG antibodies in the analysis is greater than normal, the result is said to be positive. If antibodies of this type are absent, or their titer is lower or within the normal range, this indicates a negative result.
An elevated IgM antibody titer resulting (positive) may mean that the person was infected with the infection no more than a few months ago. This is confirmed if a negative result for IgG antibodies is detected.
PCR analysis is a very sensitive method for laboratory diagnosis of infections. Its operating principle is based on determining the DNA or RNA of the infectious agent in a sample of blood, urine, or saliva. To diagnose toxoplasmosis, venous blood is usually used, less often urine.
Since PCR diagnostics is a fairly expensive method that requires high-precision equipment, it is usually used to confirm or refute the results of an enzyme-linked immunosorbent assay.
4.4
4.40 out of 5 (5 Votes)Toxoplasmosis is a dangerous infectious disease caused by protozoan microorganisms. Despite the fact that in adults the disease most often occurs unnoticed, it can pose a serious danger to the body. This is especially true for pregnant women, since toxoplasmosis can cause serious intrauterine malformations in the child.
How to identify the disease in time and protect the unborn baby from infection?
Typically, toxoplasmosis is carried by domestic cats, which become infected by eating small birds and raw meat. That is, a person can become ill with this disease when contaminated with cat feces - for example, if hygiene rules are not followed when cleaning animal litter boxes. In addition, you can become infected with toxoplasmosis after eating meat that has not been properly processed, as well as through blood transfusions from sick people. There are several forms of the disease, each of which has its own characteristics and symptoms, the most dangerous of which is the congenital form, which is transmitted from mother to fetus.
Forms and symptoms of toxoplasmosis
The symptoms and consequences of toxoplasmosis depend on the form of the disease and the characteristics of the patient’s body.
- Acute toxoplasmosis. In patients with a normal immune system who do not suffer from other diseases, it usually occurs unnoticed, without pronounced symptoms. In rare cases, the patient may have enlarged lymph nodes (most often axillary), increased body temperature, muscle weakness and aching pain in the right hypochondrium due to an enlarged liver and spleen. In an uncomplicated course, the disease goes away on its own within 1-2 weeks, after which the body develops immunity.
Acute toxoplasmosis - symptoms
- Common form. It affects people with poor health (AIDS patients, patients with cancer who have undergone chemotherapy, etc.) and is characterized by inflammatory processes in various organs: muscles, lungs, myocardium. The main danger is that the affected organs may stop functioning, which poses a direct threat to the patient’s life.
- . This form is accompanied by inflammation of the brain and is often found in patients with poor immunity. In this case, the disease primarily attacks the nervous system, which leads to the development of the following symptoms: headaches, fever, decreased sensitivity, etc. The result of infection can be paralysis and coma.
- Ocular toxoplasmosis. Most often it is a consequence of the congenital form of the disease, which manifests itself in adolescence and young adulthood. Its symptoms are pain and pressure in the eyeballs, fog, “dots” and “explosions” before the eyes, blindness.
Ocular toxoplasmosis - complication, photo
- . The result of infection of the fetus in the womb and the most complex form of the disease, which can lead to miscarriage, intrauterine death of the child or his death immediately after birth. In some cases (as happens with the ocular form), the symptoms of the disease in newborns are invisible and appear at an older age.
That is, early diagnosis of toxoplasmosis is very important for human health, especially when it comes to the developing body of the unborn baby.
Diagnosis of toxoplasmosis
Diagnosis of toxoplasmosis - methods
An analysis that allows you to detect infection with toxoplasmosis is called an enzyme immunoassay for the detection of IgM and IgG. This is a laboratory test that allows you to determine the content in the blood of immunoglobulin proteins produced in the body when fighting the disease. When conducting the analysis, special attention is paid to the type of immunoglobulins, since this factor can be used to judge the nature of the pathological process - carriage or disease.
Speaking figuratively, immunoglobulins produced after infection with toxoplasmosis can be divided into “early” and “late”. Antibodies M are produced during the acute period of infection in the first week and reach a maximum value within a month, and disappear after 2-3 months. They are detected in approximately 75% of infected newborns and 97% of adults. A negative result allows us to exclude the acute stage of the disease (less than 3 weeks), but the possibility of infection for a longer period remains.
Toxoplasmosis - analysis transcript
The production of immunoglobulins G begins 2-3 days later than M proteins, but unlike them, M proteins do not disappear anywhere and remain in the human blood for a long time (usually lifelong), providing specific immunity. Thanks to their presence, when pathogens of toxoplasmosis enter the blood again, the disease no longer develops. In other words, immunoglobulins G indicate that the acute stage of the disease has successfully passed and the human body is protected from infection. To fully verify this, an analysis is carried out for IgG avidity, that is, their ability to bind to the causative agents of toxoplasmosis for their subsequent neutralization.
If there is a suspicion of infection with toxoplasmosis, the patient is prescribed a test called PCR, which can detect Toxoplasma DNA in the urine or venous blood, which makes it possible to make a diagnosis with high accuracy.
As mentioned above, the most severe cases of the disease occur in newborns who became infected in the womb, therefore the diagnosis of toxoplasmosis is of greatest importance during the period of gestation.
How to decipher the test result for toxoplasmosis
It is quite difficult to decipher the result of a test for toxoplasmosis, since reference values in different laboratories can differ greatly from each other. Usually, when the level of immunoglobulins is above the threshold value, the test result is said to be positive, and if the level is lower, the test result is negative.
| Immunoglobulins M | Immunoglobulins G | Interpretation of the result |
|---|---|---|
| Negative | Negative | There is no infection with toxoplasmosis. Women with this result who are planning a pregnancy or carrying a child are at risk and should undergo regular examinations. |
| Negative | Positively | Lifelong immunity to the disease. Pregnant women with such indicators are recommended to do blood and urine tests, as well as determine the avidity of IgG to the causative agents of toxoplasmosis. High avidity indicates that immunity was developed in the body even before conception, that is, there is no need for further research and treatment. |
| Positively | Negative | The presence of an acute primary infection in the body. During pregnancy, such a result indicates the possibility of intrauterine infection of the child. You need to take blood and urine tests, and repeat the test for toxoplasmosis in a couple of weeks. |
| Positively | Positively | Perhaps we are talking about a primary infection with toxoplasmosis, but it should be remembered that the immunoglobulin M titer can remain positive from 3 months to 2 years. |
Avidity indicators of immunoglobulin G
| Avidity in % | Meaning | Interpretation of the result |
|---|---|---|
| Less than 40 | Low-avidity | Acute primary infection. This result in pregnant women requires additional studies to analyze |
| 41-59 | Transitional | The result is considered uninformative, so the patient is recommended to repeat the analysis in two weeks |
| More than 60 | Highly avid | Presence of immunity to toxoplasmosis pathogens. In this case, it is customary to talk about carriage or the current chronic form of the disease (the patient is not at risk of primary infection) |
Treatment of toxoplasmosis
Treatment of toxoplasmosis - treatment regimen
Most adult patients who have not previously suffered from serious illness do not require special treatment for the disease, since their immune system is able to cope with the infection on its own. Appropriate therapy is required only for pregnant women who have a risk of intrauterine infection of the fetus, children with a congenital form of the disease, as well as people with weakened immune systems. The following drugs are used to combat acute toxoplasmosis:
It is much more difficult to cure the chronic form of the disease, since it is difficult to respond to chemotherapy. Hyposensitizing and immunomodulating agents, as well as vitamins, play a key role in therapy.
Prevention of toxoplasmosis involves constant adherence to hygiene rules when working with raw meat, as well as appropriate processing of meat products before eating them. In addition, all owners of domestic cats must follow the rules for keeping animals in the apartment, especially if there is a pregnant woman there. It is very important to remember that toxoplasmosis is a dangerous disease that is easier to prevent than to cure.
Remember methods for preventing toxoplasmosis, especially during pregnancy
Video – Toxoplasmosis
