Analysis For Lamblia - How To Pass It Correctly, Decoding

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Analysis For Lamblia - How To Pass It Correctly, Decoding
Analysis For Lamblia - How To Pass It Correctly, Decoding

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Giardiasis is a parasitic infection caused by the simplest microorganism Lamblia intestinalis (Giardia Lamblia). The disease proceeds both in a latent asymptomatic form, and in the form of clearly expressed clinical signs, usually in the form of dyspeptic bowel syndrome. Below we will talk about how to get tested for Giardia.



  1. What is lamblia
  2. How is giardiasis diagnosed?
  3. Analysis of feces for lamblia
  4. Blood test for antibodies
  5. Immunoassay blood test
  6. How to prepare for analysis
  7. How to decipher the results of an ELISA test
  8. Polymerase chain reaction (PCR) method
  9. Preparing for the PCR test
  10. Decoding the results
  11. Duodenal fluid examination

What is lamblia

The causative agent of the disease is well known and studied. In the human body, lamblia exist in two forms:

  • vegetative (trophozoites);
  • cystic.

Trophozoites (vegetative forms of lamblia) parasitize in the small intestine, but migrating to the large intestine, they turn into cysts (spores), which, together with feces, are released into the external environment. Giardia in the form of cysts can maintain their vitality for a long time in anticipation of favorable conditions. Once in the human intestine, cysts turn into trophozoites, attaching to the intestinal mucosa and feeding in this way. The life cycle of trophozoites is 40 days, but the disease itself can proceed for a very long time, and sometimes take a chronic form, since reinfection (self-infection) with lamblia constantly occurs. Due to the constant existence of these protozoa in the body, a syndrome of chronic endogenous intoxication develops.In combination with a decrease in the functions of the immune system, this can lead to disruptions in the functioning of all organs and systems of the body.


Infection occurs through the fecal - oral route only from a person infected with lamblia. Giardia, a parasite in rodents, are not dangerous to humans.

How is giardiasis diagnosed?

Clinical polyformism of symptoms in giardiasis, as well as its asymptomatic course in some cases, require mandatory laboratory confirmation of the diagnosis. Research material is:

  • feces;
  • blood;
  • duodenal fluid.

Tests for Giardia include:

  • fecal examination;
  • blood test;
  • study of duodenal fluid.

Only trophozoites are found in duodenal juice, only cysts are found in feces, trophozoites and cysts are found in liquid unformed or semi-formed feces. Antibodies of lamblia are found in the blood, which reliably indicates their presence in the body.


The simplest and most accessible research method for diagnosing giardiasis is a scatological examination of feces or a coprogram.

Analysis of feces for lamblia

Analysis of feces for lamblia is a classic research method. The essence of the method is to examine warm fresh feces under a microscope. This is a prerequisite for detecting live Giardia, since they can only be found in such feces. When conducting a study, it should be remembered that cysts in feces cannot always be found. But this does not mean at all that they are not there. Just the excretion of cysts in the feces has a fickle character. Sometimes they stand out, and sometimes this process is suspended. Therefore, it is necessary to conduct a repeated scatological examination of feces or supplement this analysis with other research methods. If lamblia cysts were found in the stool, then the test is positive. A positive stool test is never false, but a negative result is very often false.


The analysis of feces for lamblia is considered a completely informative research method, but only with the correct collection of biological material (feces). The main problem when donating feces to Giardia is that biomaterial (feces) must be collected immediately after a bowel movement. It should be fresh and still warm. In other words, from collection of feces to its examination should take from 20 minutes, but not later than two hours. An evening stool sample can be refrigerated, but the information content of the stool is reduced. A two-hour stool sample is preferable as it contains the parasites in their living, active form.

Only in such material can lamblia be found in a vegetative form, that is, they are in their natural state: mobile, with flagella. It will not be difficult for a laboratory assistant to find them in this form. However, after a certain time, these protozoan parasites "understand" that some changes have occurred with their comfortable existence in the intestines. Apparently, the feces temperature, its acidity and humidity, to which the parasites react, are changing. This causes them to move into a cyst form, in which they are able to survive the unfavorable environmental conditions. Live lamblia stop moving, lose flagella, become covered with a protective membrane, hibernate, as it were, and are preserved. They can be in this state for quite a long time. But even in this state, they are well observed under a microscope, since they do not disappear anywhere.Therefore, stool stored in the refrigerator is also suitable for research. It's just that its information content decreases, but does not completely disappear.

Before taking a stool test, you should stop taking medicinal antiprotozoal agents, sorbents, laxatives for a week, and also not do enemas. Feces are taken in the morning immediately after defecation from different places: from above, from below and from the inside. The collected material is placed with a disposable spoon in a clean and spacious container.


Long-term storage of the stool taken up to 2 days is allowed, provided that the sample is placed in a special preservative liquid Turdyev. The probability of detecting parasites increases if the feces are diluted with a preservative in a ratio of 1 to 3. This allows the parasites to be kept in their natural living form for up to one month. In addition, the preservative solution makes it possible to identify lamblia without disturbing their structure, even with their minimum content in the feces.

Blood test for antibodies

A blood test for lamblia is not taken in order to detect these microscopic organisms there. Giardia is not and cannot be in the blood. Their habitat is the gastrointestinal tract: the small intestine, the large intestine or the bile ducts of the liver. Proof of the presence of lamblia in the body are special antibodies in the blood, which are produced by the immune system after receiving a signal about the appearance of foreign substances in the body. Despite the fact that the analysis of feces is still used in medicine and is sometimes quite informative, but nowadays, immunological research methods are increasingly used to identify this simplest parasite.

Today these are the most reliable ways to identify the simplest. For 10 days, a drop of blood is subjected to an enzyme immunoassay, during which negative samples are established to calculate the diagnostic density.


Until a few years ago, diagnosing giardiasis was a difficult task, much more difficult than treating it. But thanks to the development of biochemistry, the diagnosis of giardiasis has become much easier.

Immunoassay blood test

The ELISA test is based on an immune diagnostic method antigen - antibody. It is well known that our immune system reacts to foreign substances in the body (viruses, microbes, parasites, pathogenic fungi). As a result of this reaction, antibodies are formed, which should neutralize the "intruders". As a result, an antigen-antibody complex is formed. Having detected specific antibodies in the blood using this test-system (proteins that are secreted by the immune system for the appearance of parasite antigens in the body), one can confidently diagnose the presence of lamblia, even in the absence of symptoms. When a disease is detected, the test detects immunoglobulins and antibodies of the IgM type in the blood.

To detect antibodies, blood serum is used, in which specific antibodies of the IgM class are detected (10-14 days from the beginning of the invasion), and then antibodies of the IgA and IgG classes. Two weeks after infection, antibodies of the IgM class are found in the patient's blood, after which other IgG and IgA classes appear, which remain at a high level in the body at all stages of giardiasis and even after its complete cure. Antibodies disappear completely from the blood only after 2–6 months. For this reason, it is not always possible to judge with certainty about the complete recovery of the patient, since the presence of antibodies in the body remains for a long time.


The advantage of this test is that such an analysis for Giardia allows you to determine the acute or chronic form of the infection, or its residual effects, which indicates that the infection has been destroyed by the immune system. This ELISA test can also be used to study feces in which specific antigens of the GSA 65 parasites are present.

How to prepare for analysis

The analysis for antibodies to lamblia antigens is prescribed only by the attending physician, in addition, the group of immunoglobulins (antibodies) for which the analysis is being carried out should be indicated in the direction. Blood must be taken in the morning on an empty stomach, all the necessary measures must be taken first: 12 hours before the test, exclude the use of tea and coffee, alcohol or juice, you can only drink pure water. A blood sample is taken from a vein, and the result will be ready in about three days.

How to decipher the results of an ELISA test

It should be noted that the result of the obtained blood test is deciphered exclusively by a specialist. Since in such an analysis several types of antibodies are indicated that are responsible for the staging of the development of the disease.

A positive result is the following labeling> 1 OPD, which indicates that the body has a protozoal invasion of the intestine or the infection has existed in the past.

Figures less than 0.85 ODD indicate a negative result, which makes it highly likely that there are no parasites in the body.

Indicators between the interval from 0.85 to 1 ODD suggest reanalysis, since the pattern of infection is not clear. In this case, additional studies are required on lamblia: analysis of feces and study of duodenal juice.

Polymerase chain reaction (PCR) method

The essence of the method is based on molecular biology. To carry out the study, fragments of RNA and DNA of lamblia are repeatedly copied, which are in the biological material (blood) under study. Then specialists compare the fragments and identify the type of pathogen and its amount in the body.

PCR - the test is carried out in an amplifier - a special device that cools and at the same time heats the tubes with biomaterial. These manipulations are necessary in order to carry out DNA and RNA replication. The accuracy of the temperature readings affects the reliability of the result.


This method is very informative. It allows you to detect parasites even in the case when there is only one single molecule of its DNA in the sample. It is this fact that made the PCR test one of the most effective diagnostic methods.

Preparing for the PCR test

Preparation for the test depends on what biological material will be examined. If lamblia is detected, blood is used. Blood is donated in the morning on an empty stomach, in laboratory conditions, in a sterile test tube.

Decoding the results

The result of the PCR analysis can be either positive or negative. If the result is negative, this means that Giardia is not present in the body and the person is healthy. A positive result indicates the presence of segments of foreign DNA in the human blood, and speaks of his infection.

This study can give a positive result at the earliest stage of the disease, when the patient does not feel any signs of illness. Many patients are inclined to misinterpret the results of the study. However, there is no mistake. It's just that giardiasis itself may be asymptomatic, or the disease is at the first stage of the disease. How to treat giardiasis and whether to treat it at all is determined only by a competent specialist. Typically, therapeutic measures are applied only when the disease is symptomatic.

Duodenal fluid examination

Since lamblia parasitizes not only in the small intestine, but also in the duodenum, the duodenal juice can be quite informative material for research. If the analysis of fecal lamblia raises some doubts, then the study of the immediate contents of the duodenum can detect these protozoan parasites.


For this, fibrogastroscopy is done. In order for the procedure to pass with the greatest comfort, you need to carefully prepare for it:

  • three days before the alleged study, it is necessary to abandon spicy, fried, spicy foods, foods that contribute to excessive gas formation should be avoided;
  • eat light food the day before the procedure;
  • for 8 hours and research, you can not eat or drink anything;
  • also, three days before the procedure, you should refrain from smoking and alcohol, since smoking can stimulate the secretion of gastric juice, which can make an already unpleasant procedure even longer;
  • if the patient uses certain drugs every day, then the treatment cannot be interrupted, but in addition, you should consult with the attending physician;
  • the procedure lasts no more than 20 minutes.

The study of the duodenal fluid will reveal the localization of lamblia in the body, which will simplify the treatment of giardiasis.

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