A Blood Test For Toxocariasis - What Is It, Deciphering, Norm, Preparation

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

How is the analysis for toxocariasis performed?

Content

1 Danger of disease
2 Primary diagnosis
3 Complete blood count and liver function tests
4 ELISA analysis
5 Rules for blood sampling
6 Accuracy and reliability of the study
7 Analysis interpretation
8 Coefficient of positivity
9 Additional diagnostic methods

Among helminthic diseases, doctors often diagnose toxocariasis in people of different ages, which is a dangerous ailment. Toxocars, which are parasites, can penetrate into various internal organs, eyes and even the brain, provoking complications. An initial test for toxocariasis (fecal examination) may not show the presence of parasites in the body, so doctors take human blood for diagnosis.

Danger of disease

Human toxocarcosis

Toxocariasis is a disease provoked by roundworms from the order of nematodes. Once in the human body, they cause the development of various pathologies. In a person, after infection, lymph nodes increase, lymphadenopathy, bronchitis or bronchopneumonia, asthma develop, and skin rashes appear. In some cases, myocarditis, pancreatitis, leukocytosis, granuloma, keratitis are observed, and parasites may be detected in the eyeball. In medicine, there are known cases of the development of fatal pneumonia.

It is very difficult to identify the cause of pathologies of an infectious origin in the body. To correctly diagnose, the doctor prescribes a special blood test for toxocariasis, which allows you to see antibodies to parasites, to determine their number.

Primary diagnosis

The presence of helminths in the body may be indicated by the following manifestations:

A sharp onset of fever;
Decreased vision in one eye;
Lingering cough;
Fever, weakness and fatigue;
Loss of appetite and weight loss.

First, the physician studies the clinical manifestations of the disease: enlargement of the liver and spleen, prolonged cough, skin rashes. Examining the patient's skin, subcutaneous capsules are often found, in which helminth larvae are located.

Complete blood count and liver function tests

With toxocariasis, liver function tests will show a greatly increased level of bilirubin. A general blood test will show a high level of eosinophils (up to 80%), lymphocytes and ESR, as well as a reduced level of hemoglobin, which indicates that the larvae of the worms have spread to the internal organs of a person. Analysis of feces for this disease is not prescribed, since toxocars are not found in feces.

ELISA analysis

After examination, study of the history and results of a general blood test, the doctor prescribes an enzyme immunoassay (ELISA). Toxocars have antigens, which are represented by complex organic substances. The Toxocara test detects antibodies in the human body against these antigens. When they enter the human body, the immune system begins to function vigorously, producing antibodies or immunoglobulins. Their concentration in the blood is called titers. If the titers are higher than the acceptable norm, then the analysis is considered positive.

Venous blood is taken for research, while the patient should not eat food before analysis. In a blood test, antibodies against an antigen such as TES-Ag are studied. A very important stage in the diagnosis is the correct preparation of the patient, as well as the decoding of the ELISA. This method of diagnosing the disease is the most effective if you follow all the rules for its implementation.

Each laboratory has developed its own criteria for evaluating research results, so they may have slight differences. The form must necessarily indicate the norms with certain values, which determine the increase or decrease in the level of antibodies. With a positive result, the antibodies will be more than the specified rate, with a negative result, less. But not always a positive answer may indicate the presence of helminths. A high level of antibodies can indicate diseases such as cirrhosis of the liver, oncology, or tuberculosis. It is recommended to undergo re-examination after fourteen days.

Blood sampling rules

It is necessary to adhere to some rules when conducting an analysis:

Blood for toxocariasis is taken in the morning on an empty stomach, when the patient has not eaten or drank anything yet;
A few days before the procedure, you can not eat flour and fatty foods, alcohol is excluded fourteen days before the analysis;
Do not smoke for three hours before donating blood;
Antibacterial and anti-inflammatory drugs should not be taken one month before the procedure; If the patient has taken these funds, he must tell the doctor about it.

If you adhere to these rules, the result of the analysis will give reliable results, on the basis of which the attending physician will make an accurate diagnosis and prescribe an effective treatment.

Accuracy and reliability of the study

For toxocariasis, the analysis is quantitative, when it is possible to establish the number of antibody titers. But this diagnostic method can be influenced by some factors that often give a false result:

An agitated or depressed emotional state;
The presence of symptoms of colds;
Use of drugs and alcohol shortly before the procedure;
The presence of oncology, tuberculosis, liver pathology;
Autoimmune or antiphospholipid syndrome;
Pregnancy;
Long-term immunosuppressive therapy;
Individual characteristics of the human immune system;
The viability of the helminth.

Decoding analysis

A blood test for toxocariasis, the decoding of which should be studied by a physician, indicates the presence or absence of helminths in the human body:

At a titer of 1: 100, the result will be negative, which indicates the absence of parasites in the body;
At a titer of 1: 400, the result will be weakly positive, indicating that the disease is in remission (this may indicate a previous illness or an ocular form of an ailment);
With a titer from 1: 600 to 1: 800, the result indicates the progression of the disease, the person in this case is the carrier of the infection;
With a titer of more than 1: 800, one should talk about a serious disease in which pathological processes occur in the internal organs, in rare cases, an advanced form of the disease is observed, accompanied by the presence of parasites of another origin.

Positivity coefficient

Since positive and weakly positive test results may indicate the presence of other pathologies in the body, reference values are used in laboratories. Two numbers are put on the form, the first indicates normal values, and the second indicates the amount of antibodies in the patient's body. The coefficient of positivity is the difference between these two values:

From 0.9 to 1.1 - the absence of helminths in the body;
From 1.1 to 2.2 - a person is a carrier of the infection;
From 2.2 to 4.2 - the result is weakly positive, requires re-diagnosis in two weeks;
More than 4.2 - the presence of helminthic disease.

Additional diagnostic methods

When the analysis of toxocar, which is described above, gave a positive result, but there are no manifestations of the disease, doctors recommend being examined by an ophthalmologist. In frequent cases, helminth larvae can be found in the eyes, which can contribute to retinal detachment and impairment of vision. If the pathology is not treated in a timely manner, the worms completely destroy the retina, provoking complete blindness.

Blood tests for immunoglobulins may also be prescribed, which will make it possible to establish how long ago the infection occurred and what exactly caused the health problem.

If a repeated ELISA test showed an increase in titer, this indicates a recent infection with toxocars, which are currently viable. In this case, chest x-ray, ultrasound of internal organs are performed.

With a positive result of the study, treatment is prescribed immediately. Otherwise, the pathology will progress, causing complications up to and including death. The human body is unable to fight these helminths on its own.