Table of contents:
- What is lamblia
- Ways of infection with lamblia
- What is giardiasis
- Symptoms and signs of giardiasis
- Analysis for giardiasis - diagnosis of lamblia
- Indications for a blood test for lamblia
- The essence of the blood test for lamblia
- Blood test for lamblia
- Analysis for giardiasis - decoding
- How to get a child tested for giardiasis in the blood
- Prevention of lamblia
An analysis for giardiasis is indicated when there is a suspicion of this disease. Giardiasis is common enough that both children and adults can be infected with it. The analysis is usually done by ELISA. During the analysis, antibodies are determined that are produced when infected with this type of helminths.
The content of the article:
- 1 What is lamblia
- 2 Ways of infection with lamblia
- 3 What is giardiasis
- 4 Symptoms and signs of giardiasis
- 5 Analysis for giardiasis - diagnosis of lamblia
- 6 Indications for blood tests on lamblia
- 7 The essence of the blood test for lamblia
8 Blood test for lamblia
- 8.1 Preparation for the blood lamblia test
- 8.2 Blood test for IgG or IgM antibodies against lamblia
- 9 Analysis for giardiasis - decoding
- 10 How to give a child an analysis for giardiasis in the blood
- 11 Prevention of lamblia
What is lamblia
Giardia are not worms, but microscopic parasites of the protozoan class. The place of parasitism of lamblia is the upper parts of the small intestine. Giardia is attached to the mucous membrane by the front of the body, and the posterior end is free.
In one place, trophozoites remain fixed for a short time. They often detach from the villi and reattach to them, but in a different place or pass into a free state. With intensive invasion, they can penetrate into the tissues of the villi.
Trophozoites, periodically detaching from the mucous membrane, are encystised or degenerated. Experimental studies on dogs have established that 10-15 days after infection, the bulk of trophozoites are localized in the jejunum and occasionally in the duodenum.
Analysis for giardiasis. Giardia is one of the most common human parasites found in the upper small intestines. Modern data on the morphological and biological characteristics of Giardia testify to their exceptional adaptability to living in this particular part of the gastrointestinal tract.
In the future, the population of lamblia moves from the proximal to the middle or to the middle and distal parts of the small intestine. The formation of cysts (encysting) in the first 10-15 days occurs in the jejunum, rarely - in the duodenum, and later - in the middle and distal parts of the small intestine.
It depends on the size of the lamblia population, the severity of pathological changes at the site of parasitism and the age of the invasive process. Cyst discharge with giardiasis is intermittent.
Ways of infection with lamblia
The source of infection with lamblia is people infected with this parasite. In the intestines of infected people, adult lamblia are covered with a dense membrane and turn into so-called cysts, which are excreted in the feces. Giardia cysts are very resistant to external influences and can survive for a long time in the external environment.
If cysts in water or food are swallowed by a healthy person (for infection, it is enough for only 10 parasite cysts to enter the body), within a short time they will turn into adult lamblia, which will begin to multiply rapidly.
Parasites are transmitted mainly from person to person. Formed in the intestines of an infected person, the cysts of lamblia in the feces are excreted. They are resistant to external influences, able to survive for a long time in the external environment.
In children's groups, a child can become infected with lamblia through dishes, common toys. Cysts that enter the human body with food or water will turn into trophozoites in a short time and begin to multiply rapidly.
What is giardiasis
Giardiasis is one of the most dangerous infectious diseases that is asymptomatic in humans. The disease is caused by protozoa - lamblia, moving in the intestines thanks to small flagella. Infection occurs when drinking water containing the pathogen, upon contact with a sick person.
Most often, a child becomes infected with lamblia, since it is young children who neglect the rules of personal hygiene. But the disease can also be found in adults. Doctors especially insist that for any digestive disorders, parents do not self-medicate, but go to the clinic to carry out an analysis for giardiasis in children.
The peculiarity of giardiasis is that the disease for a long time may not give any symptoms at all, and a single diarrhea or vomiting is not perceived by a person as a serious illness. Often, patients write off them for poisoning and are treated on their own, without even going to a doctor.
This will save the child from serious diseases that provoke lamblia in the child's body, especially with weak immunity. Also, an analysis for giardiasis is carried out in those children who lose weight for no reason.
In order to correctly diagnose the disease and begin treatment, it is imperative to undergo a series of diagnostic tests for giardiasis. Such studies include a blood test for lamblia.
Symptoms and signs of giardiasis
The symptoms of giardiasis can be very similar to those of food poisoning or some other dangerous disease in which the patient needs urgent medical attention. In the vast majority of cases, infection with Giardia does not show any symptoms, and the infection itself disappears without any treatment within a few weeks or months.
Analysis for giardiasis. Infection with lamblia leads to the development of giardiasis, in which there is a prolonged disruption of the digestive process and other symptoms. For this reason, without adequate treatment, giardiasis can lead to severe wasting. Less commonly, Giardia colonizes the biliary tract and can cause severe liver damage.
The first symptoms of giardiasis may appear 1-2 weeks after infection, when the parasites already have time to multiply and disrupt the intestines. Giardia primarily affects the small intestine, where food is digested and absorbed.
The main symptoms and signs of giardiasis are:
- not very frequent, but prolonged diarrhea (diarrhea) in which a very foul-smelling stool is released that sticks to the toilet or pot (a sign of undigested fat in the stool). Diarrhea may last for several weeks;
- sudden temperature 38 C and above, weakness, chills;
- Sharp abdominal pain (usually in the navel)
- prolonged nausea, periodic vomiting;
- the appearance of a pink-red itchy rash on the skin;
- weight loss.
Analysis for giardiasis - diagnosis of lamblia
It is impossible to visually detect giardia during bowel movements due to their microscopic size and habitat in the upper intestines. When it enters the large intestine, a sexually mature individual turns into a cyst and already in this form leaves the body of its host for further distribution.
It is necessary to undergo an analysis for giardiasis for all children with underweight and delayed physical development, attending children's groups, persons with diarrhea of unknown origin, chronic pathologies of the digestive system, persistent rashes on the body, frequent obstructive bronchitis and bronchial asthma.
Families and their close relatives are subject to compulsory examination if lamblia is detected in one of its members. A publicly available method for detecting giardiasis is the study of fresh feces under a microscope with their preliminary staining with Lugol's solution.
The serological method helps to determine the level of antibodies (substances produced to protect against foreign elements) in the blood. After a complete cure, the level of antibodies decreases only after a few months, so it is necessary to conduct a second study to control therapy.
The features of the life cycle and the short period of existence of vegetative forms in feces suggest repeated studies to confirm the diagnosis. It is best to take the material 3-7 times with breaks of 1 week.
Duodenal intubation, when a special probe is inserted through the mouth directly into the duodenum, with further examination of its juice and bile for lamblia, gives a 100% positive result in case of infection. The use of the method is limited due to its trauma and psychological stress, especially in childhood.
An alternative and non-traumatic method for detecting giardiasis is an immunological study. It allows the detection of antigens (specific elements) in the stool. The enzyme-linked immunosorbent assay (ELISA) is informative as early as 10 days after infection.
The most reliable method for confirming giardiasis is polymerase chain reaction (PCR). It is able to detect the DNA of the parasite in biological secretions. The method is actively used for express diagnostics (stool test) of helminthic invasion.
Indications for a blood test for lamblia
An analysis for giardiasis detects the presence of parasites in the body. This may be a microscopic examination of feces, but cysts (a spore form that microorganisms acquire when they are in the rectum) are not always detected, but only in 50-70%.
Symptoms are not specific, therefore, in order to prescribe adequate treatment, the doctor needs to know for sure what causes digestive problems.
Therefore, a serological blood test for antibodies is usually prescribed in conjunction with a feces test. The doctor will prescribe this analysis if he suspects a disease.
The clinical manifestations of the disease are as follows:
- prolonged diarrhea,
- stomach ache,
- increased body temperature and chills,
- skin rash, vomiting.
The essence of the blood test for lamblia
The test for giardiasis is a serological study using the enzyme-linked immunosorbent assay (ELISA). This means that the high-precision instruments of the clinical diagnostic laboratory will identify antibodies in the blood serum that are produced by the immune system in response to the damage to the body by this parasite. They can be detected already 2 weeks after infection.
When L. intestinalis multiplies in the intestine, specific AG GSA 65 is produced in large quantities. In feces, it is determined by the method of monoclonal AT. Specific IgM class AT can be detected in the patient's blood serum by ELISA as early as 10-14 days from the onset of invasion, their presence in diagnostic titers indicates acute giardiasis.
Recently, for laboratory confirmation of giardiasis, immunological research methods are used, based on the detection of AH of the pathogen in feces or specific AT in serum.
The use of PCR for the detection of lamblia DNA in biological substrates is a highly effective diagnostic method, but it is mainly used for scientific research.
Blood test for lamblia
The essence of the ELISA diagnostic procedure is the study of venous blood, during which it is possible to confirm or deny the presence of lamblia in the body with great reliability. The decoding of such analyzes with an error of only 1 percent. Total antibodies are a good way to identify a current or previous Giardia infection.
The presumptive diagnosis is confirmed by antibodies of type M, which are found in the blood of patients with lamblia. They appear in the body in response to antigenic aggression. Blood on Giardia shows antibodies of this type already at the end of the second week after a person is infected. A little later, tests for Giardia show other antibodies of type A and G.
Preparation for analysis for blood lamblia
An analysis for giardiasis shows the presence of immunoglobulins only three weeks after infection. Also, the antibodies produced are able to persist in the blood for a long period of time after recovery.
Therefore, the serological test cannot be called 100% accurate - rather, its decoding and the results will be only clarifying. Antibiotics can significantly affect blood counts, which will lead to misinterpretation of the results and antibodies to Giardia antigens will not be detected.
Failure to comply with the rules for the delivery and conduct of immunological studies can radically distort the clinical picture, therefore it is very important to know how to prepare for a blood test for lamblia in children and adults.
Rules for preparing for an analysis for lamblia in the blood:
- do not eat 10 hours before blood sampling: as a rule, it is done in the morning on an empty stomach;
- do not drink alcohol, juices, tea and coffee before delivery;
- warn laboratory technicians about taking any medications;
- take blood from a vein;
- in the morning it is allowed to drink one medium glass of water;
- doctors do not recommend eating fatty and fried foods, salty and seasoned dishes;
- It is best to eat more fresh vegetables the day before your blood test.
Blood test for IgG or IgM antibodies against lamblia
1-2 weeks after infection with giardiasis, antibodies of the IgM type can be detected in the patient's blood. After another 1-2 weeks, IgM are replaced by antibodies of the IgG type, which remain in the human blood for a long time after recovery.
Thus, the presence or absence of antibodies against lamblia in the blood cannot serve as a reliable indicator of the presence of infection or the effectiveness of the treatment. A small amount of blood taken from a vein is used for the analysis.
Analysis for giardiasis - decoding
Currently, a blood test for antibodies against lamblia is not recommended as an accurate diagnostic method either in Russia or abroad.
The norms and interpretation of the values of titers of antibodies against lamblia vary depending on the equipment of the laboratory and therefore can be indicated and deciphered only by doctors who are familiar with the methods of work of the laboratory that performed the analyzes.
If the decryption contains IgM antibodies, then the person contracted giardiasis about a half month ago. If IgG antibodies are present in it, then the disease has passed into a chronic stage, and the immune system is actively fighting it.
ELISA decoding will contain total antibodies IgM, IgG. The final results of research will be influenced not only by the presence of these immunoglobulins, but also by their concentration.
Decoding with both classes of antibodies indicates an acute form of the disease. IgM classes can persist in the blood for up to several months after treatment, and IgG classes - up to six months.
ELISA decoding occurs by comparing the data with the indicators of the norm and positive data. Consider the main standards:
- if the norms of antibodies are increased (this is considered to be a positivity coefficient above 1.0), then human blood will contain specific immunoglobulins and the laboratory gives a positive result;
- if a blood test for antibodies to lamblia shows a result of less than 0.85, then the test is considered negative and the fact of infection with lamblia is not established;
- when the value falls within the amplitude from 0.85 to 1.0, the decoding does not allow determining the dynamics of antibodies. The analysis is repeated after two to three weeks.
How to get a child tested for giardiasis in the blood
The psychological factor in children with ELISA is that it is extremely difficult to take blood from a vein - the baby will scream and cry. Most often, in such situations, this study is simply not prescribed.
To exclude repeated studies, it is necessary to correctly pass the analysis of feces for lamblia in a child. To do this, it is advisable to observe all the nuances of the procedure for sampling feces, as well as deliver the container with them to the laboratory on time.
Research material taken from children can be stored for no more than 12 hours, and then in preservatives. Such containers with special substances can be requested from the laboratory.
It is a little more difficult for a child to take a giardia test than an adult, due to the fact that when taking blood there is a psychological factor and eating restrictions, and when taking feces - the need to defecate at a certain point in a special container.
This problem is even more acute in infants. First, it is necessary to collect the research material from the diaper very carefully - so that only those feces that have not come into contact with the diaper get into the container. Secondly, you must not miss that very moment.
Prevention of lamblia
An important place in the prevention of giardiasis is health education. It should be carried out, first of all, in risk groups, which include, in addition to those listed, persons visiting areas endemic for parasitic diseases, including giardiasis.
The attention of tourists should be drawn to the need to consume only high-quality thermally processed food products and boiled or filtered water. This will reduce the risk of contracting not only giardiasis, but also other infectious and parasitic diseases.
Find out more:
- Giardiasis (lamblia) in adults - signs, symptoms, treatment
- Giardiasis in children: symptoms, signs, diagnosis