Parasites living in the human body cause diseases of unknown etiology. There may be skin rashes, flatulence, heartburn, nausea, weakness, anemia, joint pain. Special tests should be performed to confirm the diagnosis.
Parasites that can live in the human body
Classification of parasites by types:
- round worm.
An analysis for worm eggs is required when compiling sanitary books for representatives of some professions (catering establishments, children's institutions). The same analysis is performed by children after admission to kindergartens or kindergartens or sports.
- The classic test for intestinal worms is stool analysis and rectal itching.
- However, there are several options for more effective blood tests for parasites by appointment and method.
Classical studies for worms
Worms that live in the gastrointestinal tract (gastrointestinal tract), such as pinworms, are a classic study on roundworms, fecal analysis, and removal of the mucous membrane from the rectum. However, a single stool test may not give a positive result, so it is recommended to do it three times.
- The histological coprogram method is used for the analysis of feces and debris (viewing sections of material under a microscope). The efficiency of the study is about 20%, as eggs or parasitic larvae are less likely to fall into the analyzed material.
- Controversial studies for the presence of helminths, protozoa parasites and fungi in the body are electroacupuncture methods. Their essence is to obtain results by measuring the bioelectrical reactions of active points with electrodes. Special devices are used for this purpose. Many doctors are skeptical of these studies.
- The most informed test for parasites is a blood test.
Types of blood tests for parasites
There are several options for blood tests for parasites: by appointment and method. Each of these methods has advantages and disadvantages. Depending on the method used, the following blood tests are available:
- ELISA or enzyme-linked immunosorbent assay;
- PCR or polymerase chain reaction;
- Serological blood test.
ELISA, analysis for antibodies and immunoglobulins
This analysis is based on the body's immune response, the level of protection against parasitic invasions. When antibodies are formed in the blood in response to the entry of a pathogen or simply a foreign protein into the human body, they are called immunoglobulins.
- With the help of ELISA results it is possible to determine the presence of helminths in the body and their type. The accuracy of the study is much higher than fecal analysis.
- The method is based on counting the body's antibodies against a particular type of parasite, determining its interaction with foreign antigens (the body's reaction) and the body's enzymatic response.
- Antibody complexes - antigens indicate the presence of infection.
- A blood test performed by ELISA has an accuracy of 60% to 90%, according to various experts, even at low occupation levels.
- The advantage of the method, in addition to the high level of accuracy, is that the enzyme immunoassay can monitor the dynamics of the disease over time.
Parasite ELISA blood test indicators
The antibody test appears as a series of symbols for these antibodies, or they are called immunoglobulins.
- In general, 5 of them - IgG, IgA, IgM, IgE IgD were studied.
- The first four immunoglobulins are important in practical medicine.
IgM is a key indicator in the acute phase of the disease
IgM - immunoglobulin seen in the acute phase of the disease indicates the onset of infection.
- appears in the blood on the fifth day,
- It was detected by analysis after 6 weeks.
- Then it begins to fade rapidly.
IgE - an indicator of infection with parasites, an indicator
IgE - immunoglobulin indicates the presence of parasites or allergies in the human body.
- is a marker of allergy-related processes,
- circulates less in the blood, in mucous membranes, macrophages and basophils,
- Participates in immune reactions against parasite invasion.
IgG - an indicator of past illness and immunity
IgG - immunoglobulin, appears in the course of the disease.
- IgG continues after healing because some infections, such as measles, rubella, and others, last a lifetime.
- Detection of immunoglobulins G in the blood indicates that the body is already exposed to this infection with this pathogen.
ELISA result for immunoglobulin variants
The following results can be obtained for various positive and negative compounds in a blood test for parasites:
- no infection - all antibodies that are negative;
- acute phase - IgG (+/-), IgA (+ \ -), IgM (+);
- chronic form - IgG (+/-), IgA (-), IgM (-);
- presence of immunity - IgG (+), IgA (-), IgM (-);
- exacerbation of a chronic disease - IgG (+), IgA (+), IgM (+)
- If the disease is diagnosed and treated, the negative values of all antibodies will reach only six months after the course of treatment, sometimes 1-2 years.
Reliability of ELISA analysis
The ELISA method provides a 90% confidence level for the diagnosis of infections with roundworms, pinworms (enteriobiosis), toxocaras, etc. , which cause the formation of large amounts of IgG immunoglobulin in the blood.
- Giardiasis can be diagnosed with a separate and total (OPd) antibody level in the blood.
- An ODD value of more than 1 indicates the presence or absence of infection
- if the value is less than 0. 85, there is no lamblia.
- If the price is in the range, it is recommended to repeat the analysis after 2 weeks.
This method is characterized by a number of disadvantages. The analysis allows you to determine the level of antibodies produced in the body to neutralize the helminths, not the worms themselves.
- Therefore, it is possible to get false positive and false negative results.
- This also happens when patients take medication,
- presence of metabolic diseases and parallel current chronic diseases.
Complete blood count, changes in parasite invasion
Therefore, you can suspect the presence of an invasion by performing a general blood test. Because the presence of worms affects the internal organs, the products of their vital activity enter the bloodstream by changing their composition. Partial list of effects of heat on blood parameters:
- increased hemoglobin;
- abnormal ESR indicators;
- more than 20% of eosinophils;
- glandular anemia.
If there is no other reason for such deviations, it is recommended to include in the diagnostic program a special blood test for parasites, ELISA, PCR.
Polymerase chain reaction, PCR analysis
The PCR method or polymer chain reaction is the basis of molecular diagnostics and is one of the most modern and accurate methods for diagnosing the presence of parasites in the body.
- It consists of the detection of traces of DNA and RNA belonging to parasitic life forms.
- The essence of the polymerase reaction is that the blood is copied and reproduced to a concentration that allows it to determine the DNA and RNA of foreign organisms.
Serological blood test
This analysis uses the blood source as a source of information.
- Immunogenic reactions of antibodies to parasitic antigens are investigated.
- The analysis allows to identify a large number of parasitic forms, but does not allow to determine the stage of occupation.
- Like the ELISA method, serological analysis is also indirect for diagnosis.
- If OPD values are high, additional fecal analysis is recommended.
Diagnosis by blood hemoscanization
During hemoscanization of parasites, a drop of the patient's "live" blood is examined with optical devices, in addition to the eggs of worms, their larvae and fungi can also be identified.
How to do a blood test for parasites
Blood donation for parasites is carried out in a special laboratory. For analysis, blood is taken from the cubital vein in a volume of 3-5 ml and placed in a dry sterile test tube. Before starting the test, it is recommended:
- Do not eat for 8 hours;
- avoid fatty foods and milk at dinner;
- do not drink alcohol and carbonated beverages;
- avoid unnecessary physical activity, physiotherapy, X-rays;
- Refuse to take medication.
- It is recommended to drink plenty of fluids.
- Blood donation conditions for PCR are less stringent because the degree of saturation does not affect the presence of parasitic DNA.
Terms of analysis
- The results of ELISA and serological tests are given within a week.
- A few hours are enough for PCR blood analysis and hemoscanalization.
- As a result of the analysis, you must consult a doctor.