Human infection with worms of the genus Toxocara canis can be confirmed only if the IgA antibody titers to toxocar antigens were detected in the blood in the ELISA( enzyme immunoassay) diagnostics. The complexity of determining the disease caused in humans by these parasites is connected with the fact that their larvae in humans never reach the sexually mature state. Therefore, in feces and duodenal contents of adult individuals or their eggs can not be detected. That is why serodiagnosis, a study that detects the antigens of these worms( IgG and IgE immunoglobulins), is the most effective test for this helminthiasis. Also, it is always used to control the results obtained during treatment of the infection. This analysis is necessary in the following cases:
- The patient suddenly had a fever of unknown origin or signs of lung and liver damage against the background of eosinophilia. This symptomatology usually indicates a possible infection with nematodes;
- With a sharp decrease in vision, one eye is also needed for this study;
- In children, the analysis for antibodies to toxocaram( titer) is carried out for epidemiological reasons, such as contact with contaminated land and stray dogs;
- Also the detection of IgG and IgE immunoglobulins is necessary when a person has eaten poorly processed foods that are possibly infected with toxocara canis.
The study is also mandatory for people at risk - veterinarians, farmers, dog handlers. In addition, a blood test showing the presence of antibodies to IgG toxogens is also prescribed in differential studies conducted in other helminthic invasions.
How to decipher the results of ELISA for antibodies to antigens toxocar( titer)?
The results of the IgG blood test for antigens of toxocar, carried out by ELISA, allow us to determine with the greatest accuracy how long the patient has infected them. The decoding of the title indicates to the specialist whether there are any IgG antibodies to the toxocar antigens in the human blood. In the case where the titers are 1: 100, the answer is negative. Numbers from 1: 200 to 1: 400 are placed when the patient is a carrier of toxocar, and also can be affected by larvae of central nervous system worms or eyes. If the titer set in the study sheet is 1: 800, it means a positive result, that is, antibodies to toxograms IgG are detected in the blood and the disease progresses. In separate laboratories, the positivity index is used to detect parasites. In the explanations for the analysis, the following transcript is indicated:
- & lt; 0.9 - negative, that is, helminths of the form toxocara canis not detected;
- Index idx from 0.9 to 1.1 the presence of parasites is doubtful, repeated diagnostics by ELISA is required;
- idx & gt; 1.1, but & lt;2.2 - positive, this means that titers of IgG antibodies to toxocar antigens are present in human blood, but it is the carrier of pathogens;
- If the positivity index is higher than 8.0, as well as the number of eosinophils exceeds 10%, the specialists no doubt put the diagnosis of "toxocarosis".
In the responses to IgG antibodies for antigens, there are also reference values to these parasites, that is, the norm. The unit of their measurement is the coefficient of positivity or KP.In the case when the data of both graphs coincide, or are less than 1.0, there are no antibodies that indicate the presence of toxocarias in the patient. Values of CP from 1.0 to 4.4 give a weakly positive response, in which a re-examination is necessary to the pathogen of the species toxocara canis. And in the case when the CP is above 4.4 - positive, that is, the presence of an agent is determined and immediate treatment is required.
Many people who have faced development in the body of this invasion and detection of it with the help of immunoassay research are also interested in the question of how many IgG antibodies are retained to toxocaram. The specialists' answer to this question is that ATs on the AG IgG class to the larvae of these parasites can persist for a long time. Also, often patients are also interested in what these records mean in the study sheet: Toksokary 1: 100, 1: 200, 1: 400 and 1: 800.Although this question was answered above, all the same it should be repeated that these titles mean the presence or absence of pathogens in humans. So 1: 100 - the norm, that is, the complete absence of AT to the AG pathogen, 1: 200 or 1: 400 - a weakly positive result that requires a second study, and 1: 800 - positively, that is, antibodies total antigens toxocar are present and confirm the presence of thishelminthiosis.
When a person contacts these worms, his immune system produces IgG and IgE immunoglobulins to the pathogens in certain amounts. After infection, their appearance is possible in 6-8 weeks, but their concentration increases to maximum after 2-3 months and remains at this level for a long time. The degree of increase in their concentration is associated with the severity of the disease.
Antibodies total to toxocaram in children
Parents encountered in the certificate issued to the child with the record "idx index to anti toxocara titre" and then comes a numerical value, usually they are interested in what it means. Such a record is put in the case when a patient having a symptom similar to toxocarosis takes the blood for antibodies that are total to the antigens of these parasites. If the titer shows a value of less than 1: 100 or a complete absence, this is the norm, that is, the kid completely lacks this kind of worms. Any increase in titers on AT to AH will indicate a weak or severe infection, as well as a previous illness. The received data are recorded by the following terms:
- Negative( less than 1: 100);
- It is doubtful( from 1: 200 to 1: 400);
- Positive( 1: 800 and higher).
In the case when a titer value exceeding 1: 1600 appears in the child analysis data, this indicates that the baby has not only antibodies to toxocar antigens, but there is also an infection with another type of worm. But low values also can not unequivocally testify to the complete absence of infestation by these parasites, since they can be given by larvae that are in the child's eyes or visceral type of the disease. That's why parents should be very careful and when children even have a minimal amount of IgG antibodies, which indicate a possible infection with toxocaram, do not avoid seeing a specialist. This will help in the appearance of other signs that speak of the development of this invasion, to begin timely treatment, which guarantees the full recovery of the child.
In small patients, as well as in adults, false data obtained when detecting antibodies to toxocaram by analysis is possible. So about a false presence in the body of parasites can say immunodeficiency or lymphoproliferative diseases. Doubtful data give eye lesions that result from a small antigenic effect. That is why infectious disease doctors, when a corresponding symptomatic toxoma appears in a person, possible in other parasitic infestations, or suspected of an infection, one test that reveals the presence of antibodies to these parasitic worms in the body is not limited. Also, specialists of sanitary epidemiological stations regularly identify territories that present an epidemic danger and conduct preventive measures on them.