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Analyzes of lamblia: interpretation

Suspicion of parasite infestation occurs when there are persistent dyspeptic disorders. Giardiasis is a protozoal infection caused by the smallest intestinal parasites of Giardia or Giardia. The disease is well researched, modern methods of its treatment give a 100% cure effect. The main thing is the timely diagnosis of infection by these parasites, and the physician can learn the basic information from the results of laboratory tests for the presence of a lambliosis patient.

Preparation for analysis on Giardia

The negative result of research does not at all mean that there are no parasites. Analyzes for the presence of lamblia are usually taken repeatedly. Often in a dubious result the patient himself is guilty. Observance of several simple rules before passing the analysis will make the research results more accurate. Therefore, how to take the analysis for Giardia, so as not to waste time?

Intending to take the tests, you need to stop taking anthelmintics at least seven days before the scheduled time, as well as drugs that can harm parasites: antibacterial (metronidazole, trichloropol), antacid (smect). It is advisable, if possible, not to take any medications at all.

A blood test for antibodies to lamblia (enzyme immunoassay) is given on an empty stomach in the morning from a vein. Before taking blood for 10 hours, it is necessary to stop eating food and any drinks, except for pure still water.

Cal for analysis is collected from the liquid fraction in six to seven places and is sealed in a sterile container with a sealed cap. It is desirable to collect it in the morning and deliver it to the laboratory as quickly as possible within two hours. If you deliver feces in 20 minutes, then in this case, the laboratory assistant will be able to detect vegetative forms of parasites. Within 12 hours - formed by them cysts. Longer delivery times reduce the informative value of the analysis. However, often the medical staff requires that warm feces be delivered to the analysis. This requirement is problematic and it is illegal, from the moment of defecation to the receipt of the analysis by the laboratory should take no more than 12 hours. You can ask for a container in the laboratory with a preservative that will extend the shelf life of the material.

Feces on the antigen are collected in a sterile container, preferably immediately delivered to the laboratory. If this is not possible, the container can be stored, keeping the temperature 2-4 ° C (in the refrigerator) one or two days. A single deep freeze (-20 ° C) is also permissible, if longer storage is assumed. The material for the study is collected within the first week of the onset of clinical symptoms.

On the question "Where to pass the analysis on ljamblii?" - the doctor who will write out a direction on the analysis most simply answers. Such an analysis is done in all laboratories of polyclinics, hospitals and in commercial laboratories.

More patients often wonder: how much is the analysis prepared for lamblia? Stool analysis is prepared quickly enough as soon as the sample reaches the microscope. It's just that the result should be formalized, usually it is ready in the second half of the day of the analysis.

A blood test for antibodies to lamblia will be ready in two days, feces for antigen - every other day. The result of PCR analysis on lamblia is ready in 4-6 hours.

Comparative efficacy of diagnostic methods

The blood test for antibodies to Giardia - indirect diagnostic method because they are formed in the blood as an immune response to parasitic infestation. Do not appear immediately, but within two, and sometimes three weeks, so in the first few days after infection, the result will be false-negative. The presence of immunoglobulin M says a recent infection, but they do exist and are replaced by long of IgG, whose presence confirms that the invasion was. But they can persist long after recovery and do not indicate the need for treatment, and therefore are not suitable for monitoring its effectiveness.

Indicator of presence of antibodies depends on many factors, particularly the immune system and the infection rate. With low immunity or chronic relapsing giardiasis antibodies with persistent current can not be detected. Occur and false positive test results in the case of other protozoa infestation, for example, amoebiasis, antibodies which can be taken as Giardia antibody.

Fecal Giardia is more reliable. He is to examine the stool samples taken from several locations, under a microscope, and visual search of live animals or their cysts. If the result is positive - it means exactly the parasites there. A negative result does not mean that the patient is healthy. Just in the development of the parasites happen so-called "blind" periods, their duration of 1-17 days, which does not occur tsistovydeleniya. If the analysis is collected and deposited in this period, the result will be negative even in the presence of parasites. Therefore it is recommended to take fecal Giardia cysts at least three times every three days. If the suspicion of the presence of parasites seriously, cal monitored for a month or one and a half, every week.

Two of the above analysis of blood and stool samples are most often used, since they make the majority of laboratories. Research is usually given as a blood and feces. If one of the tests is positive, it is possible to infer the presence of infection.

Analysis on lamblia antigen is more informative than stool microscopy, but its availability is limited, since it is done only in big cities and not all commercial laboratories. The basis of the study material is put a one-step immunoassay method to detect specific molecules (antigens GSA-65), which are located in the cells exclusively lamblia. For research mainly come from fecal samples, but biopsy is sometimes used. Immunoassay method can detect giardia, even in "blind" period. It should be used to monitor recovery, but after a two-week interval after the cancellation of reception of preparations as the antigen may even be allocated to this time slice.

To identify the most informative of parasites is now the analysis of PCR for giardia. Its main drawback - the lack of prevalence. He did not make it practically in any laboratory, even in large cities. This study, using the polymerase chain reaction to identify in stool fragments deoxyribonuclease lamblia even in the gap when the cysts are not allocated. The accuracy of this assay is the highest (98%).

Interpretation of the values of the analysis on Giardia

The results obtained in the determination of  serum antibodies to lamblia are compared with the reference indices. The lower limit of the norm of preserving the activity of antibodies is fixed in the proportion 1: 100. The activity of immunoglobulins less than 1: 100 is estimated as a negative result. With an activity exceeding this ratio, a conclusion is drawn about the presence of giardiasis. The antibody titer exactly 1: 100 is interpreted as ambiguous. The analysis is recommended to be repeated, as well as the analysis of feces for lamblia cysts.

The IgM positivity coefficient is greater than 1 and less than 2, speaking about the level of serum antibody concentration, in combination with the absence of IgG is diagnosed as the initial stage of giardiasis.

The positive factor of immunoglobulin class M equal to two in combination with the detection of cysts in microscopy of feces is usually interpreted as an acute lambliasis.

When cysts are detected in the analysis of stool, absence of IgM, and the level of IgG concentration equal to 1-2, chronic lambliasis is diagnosed.

Positive analysis for the definition of IgG causes doubts in the unambiguous presence of lamblia in the body, since the G-class immunoglobulin is determined in the blood serum for another six months after the cure.

Norms of  analysis of feces on Giardia  - the absence of any form of parasites. In the presence of living individuals or their cysts, the analysis is considered positive.

The negative result of  analysis of stool for lamblia antigen  should be very likely to indicate their absence. However, it can be with a small number of cysts in the feces, while a second study can produce a positive result. Therefore, if there are clinical manifestations, the analysis is repeated. A positive result indicates infection or carriage.

Analysis of PCR on Giardia can be positive in determining the DNA of these parasites in biological material and negative in their absence.

None of the above analyzes in itself does not give 100% of the result, so a diagnostic interpretation is built up with a comprehensive analysis of all available survey data.

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