In the article, we consider what an analysis of toxocariasis is.
Infection with worms is widespread among the population due to the fact that most of us contain pets, and there are many professions whose activities are related to animals. Adult toxocariasis is a severe parasitic disease characterized by damage to many internal organs.
This is an infection caused by a parasite of the genus toxocara of the Ascaris family. The disease occurs when foods that are contaminated with soil are consumed. The eggs of the embryos of this parasite penetrate into it with animal feces. Parasites act as geohelminths. As a rule, embryogenesis in the soil occurs within two to five weeks after elimination by animals. Thus, the process of infection with toxocariasis is not carried out as a result of contact with feces.
Pathology Description
This infection is a larval helminthiasis. Infection occurs by swallowing eggs along with certain foods. Patients are presented with complaints of abdominal pain, trouble sleeping and coughing. Sometimes, a slight increase in the size of the liver can be determined along with an increase in temperature to subfebrile indicators. The nature, as well as the severity of clinical symptoms, directly depends on the intensity of infection and the area of localization of granulomas in organs and tissues. Doctors often find damage to the lungs, spleen, liver, and eyes.
What is a toxocariasis test?
Types of research
There is no final diagnostic technique for this infection. In turn, true sensitivity along with the specificity of serological tests cannot be determined by accuracy. To make a diagnosis, a comprehensive examination is usually carried out, including the delivery of an analysis for toxocariasis in combination with general clinical, radiological and other studies.
The determination of the diagnosis by a blood test is complicated by the variability of the immune response, which depends on the degree of infection with pathogenic parasites and the localization of this infection. True, numerous studies demonstrate that the enzyme-linked immunosorbent blood test for the infection in question, which uses purified antigens isolated from the larval stage, has better specificity and sensitivity compared to other options that use untreated antigens.
Indications for appointment
Such a study to patients, as a rule, can be prescribed in a number of the following cases:
- As part of the diagnosis of toxocariasis.
- For differential diagnosis of parasitic diseases.
- Exercise control over ongoing treatment.
Decryption of the analysis for toxocariasis
The results of a research test must necessarily correlate with clinical diagnosis, as well as with other laboratory tests. Negative results in decoding a blood test for toxocariasis do not exclude disease. Due to the low level of antibodies in the early stages of infection, tests may show dubious or negative findings.
In the event that there is a clinical suspicion of infection, the test must be repeated after two to four weeks. A cross reaction with other nematodes is not ruled out. Therefore, five to ten percent of healthy people have antibodies to toxocara, and positive results do not always mean the presence of a parasite in the body.
A false positive test for toxocariasis is possible in individuals with systemic lymphoproliferative pathologies and immunodeficiency. This leads to the need for research into the clinical picture of the disease. A false negative and dubious result of the study is possible in people with eye damage as a result of a weak antigenic effect.
How to prepare?
How to take an analysis for toxocariasis, it is better to find out in advance. As part of the preparation, it is recommended to adhere to the following rules:
- If it is possible to donate blood, it is necessary in the morning from eight to eleven hours on an empty stomach (at least eight and not more than fourteen hours of hunger, water is used as a drink). On the eve, it is important to avoid food overload.
- In the event that a person is taking any medications, he should definitely consult a doctor about the advisability of performing the study. It is also worth considering the feasibility of drug withdrawal before the study. In this case, the duration of withdrawal is determined by the period of withdrawal of the drug from the blood (on average, it is recommended to wait from four to five half-lives of the drug indicated in the annotation attached to it).
- In preparation for the analysis for toxocariasis, alcohol is excluded on the eve of the planned study.
- Do not smoke for at least one hour before analysis.
- Physical and, in addition, emotional overloads are excluded on the eve of the test.
- After the patient arrives in the laboratory, he should rest (for example, sit) for ten to twenty minutes before taking the blood.
- It is undesirable to take an analysis to conduct a laboratory study shortly after a physiotherapeutic procedure, instrumental examinations and other medical manipulations. In the case of some clinical measures (for example, rectal examination or prostate biopsy), laboratory examination for toxocariasis should be postponed for several days.
Where to get tested for toxocariasis?
A study to determine the described infection is currently being conducted in any budget and private clinical laboratories. The study is usually performed within three days, excluding Sunday (in addition to the day of biomaterial sampling). Patients receive the results of a blood test for toxocariasis by e-mail immediately upon availability.
Diagnostics
The diagnosis is made to patients based on symptoms and epidemiological data. In laboratory studies, against the background of toxocariasis, the following changes can occur:
- Leukocytosis along with eosinophilia indicates an increase in the number of eosinophils and white blood cells in the peripheral blood. This phenomenon is able to reach a high value (from twenty to forty percent), which does not happen with banal helminthiasis. It is worth noting that this serves as an important diagnostic symptom. In case of liver damage, hepatic transaminases may increase along with alkaline phosphatase.
- The growth of immunoglobulins of classes E and G. A similar increase will confirm the appearance of toxocara-specific immunoglobulin G. It should be noted that the sensitivity of this indicator is low, since it does not demonstrate the development of the disease, but that the human body has encountered this parasite before. For diagnosis, a combination of an increased titer to toxocara along with the presence of blood eosinophilia is important. In this regard, it makes no sense to perform the analysis with a high-quality technique (positively - negatively). Only a quantitative analysis will be required. Very rarely, an increased amount of antibodies can be combined with normal eosinophilia. As a rule, this occurs with minor toxocara infections.
- Conducting radiation diagnostics. In case of damage to the internal organs in patients, toxocariasis nodes are detected within the liver, in the nervous system and lungs. Not infrequently, such formations are confused with metastases. Ultrasound, x-ray (radiography, tomography) and magnetic resonance imaging can be applied.
Fecal analysis
The diagnostic feature is that the standard method of analysis of feces for toxocariasis will not be able to detect larvae, since the parasite in the human body does not multiply. Therefore, you should be aware that the analysis of feces as part of the definition of an ailment is never used.
Enzyme immunoassay (ELISA)
The most optimal is the ELISA for toxocariasis, which identifies IgG antibodies to the larvae of the parasite in question. Antibodies are components of the body’s immune system that are produced to destroy certain foreign antigen proteins. In this case, toxocar larvae act as an antigen.
There are several types of antibodies, for example, IgD, IgG and others. But, nevertheless, the immune system can not cope with the parasite even with a high concentration of these protective mechanisms. Each of these antibodies has its own functions and period of appearance. For example, IgG is produced fifteen to twenty days after infection and can persist in the blood for quite some time. Therefore, the detection of such an antibody in the analysis results will indicate a chronic course of toxocariasis.
Thus, antibodies to toxocara parasite antigens are one of the most effective types of tests in the diagnosis of toxocariasis and monitoring the effectiveness of therapy. The causative agent of toxocariasis, as previously noted, is the nematode, which is usually parasitic in dogs, and in addition, in wolves, foxes, and other representatives of the canine family. The main diagnostic technique for the diagnosis of toxocariasis is the detection of IgG antibodies to parasite antigens in blood serum.
Toxocariasis Prevention
The basis of prevention is the observance of hygiene rules. Children should not be allowed to play in the sandbox, which dogs and cats have access to. Do not eat foods and liquids that have not undergone appropriate heat treatment. Infection from your own pet is unlikely. Studies have shown that the likelihood of infection with toxocariasis is the same for dog owners and those who do not have animals at home. The means of collective prevention is cleaning feces of pets in the streets after defecation.
Conclusion
Thus, the main hosts of this parasite are dogs and cats. And the main source of infection of animals are eggs of pathogens in the external environment. Against the background of their ingestion, larvae emerge from the eggs, which penetrate through the intestinal wall into the bloodstream, migrating to the lungs, where several stages of larval formation take place, and then through the esophagus they again enter the digestive system, where they develop even before degeneration into adults. With animal feces, parasites enter the environment. As part of the definition of toxocariasis, a blood test is performed.