A Blood Test For Toxoplasmosis - How To Take And Decoding

2023 Author: Riley Dean | [email protected]. Last modified: 2023-08-25 08:37

Toxoplasma test procedure

Content

• 1 How does infection occur
• 2 Why is an analysis for toxoplasmosis necessary?

• 3 ELISA

  • 3.1 Information about Ig M
  • 3.2 Information on Ig G
  • 3.3 Interpretation of the analysis by indicators of immunoglobulin
  • 3.4 Interpretation of Avidity Analysis Results
• 4 PCR

It is urgently necessary to take a blood test for toxoplasmosis for women who are in a position, or planning to become pregnant in the near future, only timely diagnosis of this parasitic disease can prevent serious illnesses of the unborn child or miscarriage.

How does infection occur

How does infection occur

You can become infected with the parasite from pets, most often cats are the carriers. Doctors advise pregnant women to avoid close contact with cats some time before conception and throughout pregnancy. The carriers of the parasite are also intermediate hosts, most often mice, although in their body the parasite cannot be in the form of cysts, therefore this method of transmission of the parasite is absolutely safe for humans.

Often, infection occurs through the meat of farm animals, especially through the meat of sheep or pigs. That is why you should not eat undercooked or raw meat. Even if there is no toxoplasmosis in meat products, there is a high probability of picking up in this way no less dangerous parasites, for example, bovine or pork tapeworm. It is possible to exclude infection through animal meat only if all food undergoes sufficient heat treatment.

You can become infected with the parasite through the blood. So, infected blood-sucking insects are especially dangerous to humans, they contribute to the penetration of Toxoplasma directly into the bloodstream through damaged skin. In a similar way, infection occurs during blood transfusion or organ transplantation from a sick person, however, this may only be due to medical negligence.

An analysis for toxoplasmosis is necessary for pregnant women, since the intrauterine method of infection with the parasite is recognized as the most dangerous. In this case, the infection of the fetus occurs directly in the womb of a sick woman, the parasite easily penetrates the placenta and causes serious disturbances in all organ systems in the child. If a blood test for toxoplasmosis showed positive results, this can be a serious reason for the artificial termination of pregnancy.

Why is a toxoplasmosis test necessary?

As mentioned above, toxoplasmosis in most infected patients proceeds without visible symptoms, so it is simply impossible to detect the presence of the parasite without laboratory tests. Toxoplasmosis is especially dangerous during pregnancy, it has been established that if an expectant mother is sick with a parasite, then with a probability of 70% it will be transmitted to her unborn child. Intrauterine infection in the future for a child can result in severe damage to the nervous system, eyes and other organ systems.

Blood for toxoplasmosis is donated not only in order to determine the presence of the parasite in the body, but also to establish with maximum accuracy when the infection occurred and how the body reacts to it. Since the body in most cases forms immunity from dangerous diseases, then if a woman has already been ill with a parasite 3-4 months before conceiving a child, she has absolutely nothing to fear - the body has developed a stable immunity and re-infection will not occur.

Today, the most effective tests for toxoplasmosis are considered to be enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) analysis; they can be easily done in any diagnostic laboratory.

ELISA

ELISA method

With the help of an enzyme immunoassay, the content of certain immunoglobulins in the body is determined. Immunoglobulin IgM is produced by the body immediately after infection with toxoplasmosis, IgG antibodies indicate the beginning of the development of persistent immunity to parasites.

An enzyme-linked immunosorbent assay for toxoplasmosis is a clinical examination of biological material, as a result, the presence of antibodies that fight toxoplasmosis is determined.

It is worth saying that the body gives an immune response to any infection in the human body, how many dangerous viruses, parasites and other pathogens exist, so many types of immunoglobulins. Antibodies with the help of the bloodstream are successfully spread throughout the body, bind to the infection and neutralize it after a while. In the case of toxoplasmosis, some time after infection, the body develops strong immunity, which prevents further infection.

Information about Ig M

As mentioned above, for each disease, its own type of immunoglobulins is produced; when infected with Toxoplasma, antibodies also have a different appearance depending on the stage of infection. So, distinguish between "early" and "late" antibodies, which determine the time elapsed after infection. These data are taken into account when conducting laboratory examinations of the patient's biological materials.

The first type of immunoglobulins M is produced by the body in the first days after the disease. When it takes about 2-3 weeks after infection, the content of the substance in the body reaches a maximum, 1-2 months after toxoplasmosis, the immunoglobulin disappears without a trace and does not show itself in the analyzes. If, during the analysis for toxoplasmosis, immunoglobulins M are recorded in the blood, we can say that the disease is in an exacerbation stage.

Information about Ig G

Immunoglobulins G appear in the body 2-3 days after infection; they reach their maximum amount a month after infection. Unlike antibodies M, immunoglobulin G does not disappear anywhere and continues to be in the body until the end of life, providing strong immunity and preventing re-infection of the body.

If antibodies G are found in the body during the analysis, we can say that the body is ready to fight the disease, and there is no threat to the fetus.

It is worth noting that each laboratory that conducts research on toxoplasmosis has its own threshold values for the content of immunoglobulins. If the antibody content is below the threshold level, a negative diagnosis is made, above the threshold level, a positive one.

Deciphering the analysis by indicators of immunoglobulin

Immunoglobulin M	Immunoglobulin G	Analysis results
Negative	Negative	There is no parasite in the body. If such a test result is recorded in a pregnant woman, she is at risk and must undergo tests for toxoplasmosis every trimester of pregnancy. It is advisable to exclude any contact with pets that may carry the parasite.
Negative	Positive	The body began to develop a strong immunity to toxoplasmosis. During pregnancy, more research is needed to determine the ability of antibodies to bind to parasites and destroy them. If, according to the results of an additional examination, a high avidity to parasites is diagnosed, immunity was acquired before the start of pregnancy, and the patient does not need further examinations.
Positive	Negative	The infection occurred a few days ago, during pregnancy there is a high probability of transmission of the parasite to the fetus through the placenta. It is necessary to conduct an additional analysis after 1-2 weeks, if the G antibodies are positive and the parasite's DNA is not detected, treatment is prescribed. Sometimes the test can be false positive.
Positive	Positive	Such results are possible with primary infection. Remember that M antibodies in the body of an infected person can persist for 2-3 months after an illness. An additional study is prescribed for the avidity of antibodies to toxoplasmosis.

Decoding the results of the analysis for avidity

Avidity	Value
Less than 40%	Acute primary infection. During pregnancy, additional PCR examinations are necessary.
41-59%	Invalid result manifested during the transition period. It is necessary to re-examine in 2-3 weeks.
More than 60%	The body has developed a strong immunity to toxoplasmosis. With such indicators, a person can act as a carrier of the parasite. Primary acute infection is not threatened, the fetus is safe.

PCR

PCR method

Inside Toxoplasma is DNA, which contains all the hereditary information about the parasite. The PCR method is based on the identification of the DNA or RNA of the parasite in the patient's biological material (most often blood, but sometimes saliva, sputum, amniotic fluid, urine). With the help of the analysis, it is possible to determine with high accuracy at what stage the disease is. Despite all the information content of the analysis for toxoplasmosis, it is used only when other studies do not give an accurate answer to the question of parasite infection.

The research method has its drawbacks. Firstly, this is a high price; not every patient can afford such a study. Secondly, high requirements are imposed on equipment for the study of biological material.

PCR analysis can be positive or negative. In the first case, the result means that a parasite develops in the body; in the second case, the pathogen is not found in biological materials. The test allows you to identify the parasite, if its amount in biological materials is extremely small; using the PCR test, the disease is often detected at an acute stage.

There is no need to prepare for ELISA and PCR analyzes, while it is advisable to take biological material on an empty stomach; the day before the analysis, it is better to stop eating heavy and fatty foods.

Tests for toxoplasmosis are highly effective methods for examining the body, which allow not only to identify the parasite in the body, but also to determine at what stage the disease is. It is advisable to do such studies for pregnant women or women who are planning to conceive a child in the near future, often the disease does not manifest itself with specific symptoms, while it is very dangerous for the unborn child.