According to medical statistics, a huge number of people are infected with parasites. Helminths and simple microorganisms very easily penetrate the human body. Often, the invasion is asymptomatic, and infection can be detected only with the help of special studies. What parasite tests are most often used in modern diagnostics? And how to decipher the survey results? We will consider these issues in the article.
Types of analyzes
What tests are tested for parasites? Most often, with suspected helminthiasis and giardiasis, doctors recommend passing the following examinations:
- Fecal analysis. There are various methods for determining parasites in feces. Most often, the biomaterial is examined under a microscope. Today, the PCR diagnostic method is also used, which allows you to accurately determine the presence of parasites in the intestine.
- Blood analysis. This is the most reliable study. It helps to detect antibodies to helminths and protozoa, as well as parasite DNA.
- Analysis of mucus from the anal area. A scraping is taken from the skin around the rectum for examination and sent for microscopy.
Only a specialist can determine what examinations the patient needs to undergo. A traditional method for detecting helminths is the analysis of feces for worm eggs. However, not all parasites can be detected in this way. Therefore, at present, blood tests for antibodies to helminths are more often used.
Indications
Doctors prescribe tests for parasites if the patient has the following symptoms:
- unreasonable weight loss with normal nutrition;
- constant feeling of tiredness;
- irritation and itching in the anal area;
- signs of general intoxication of the body;
- dyspeptic manifestations (diarrhea, nausea, vomiting, bloating);
- allergic skin reactions (itching, rashes);
- sleep disturbances;
- decreased immunity;
- hemoglobin drop;
- inflammation in the genitourinary area of unknown etiology.
Such symptoms may indicate the presence of helminths or protozoa in the body.
Research on parasites is carried out not only for the diagnosis of diseases, but also for preventive purposes. A number of such tests are required to design a medical book. This document is necessary for all people whose activities are related to food, as well as employees of childcare facilities and medical personnel.
In childhood, helminthiasis and giardiasis are especially common. Therefore, every child must be tested for parasites when entering kindergarten or school. Pediatricians recommend undergoing such an examination at least 1 time per year in order to detect invasion on time.
Analysis of feces for worm eggs
This is the most common type of analysis for parasites. He diagnoses the presence of the following types of worms:
- nematodes;
- tapeworms;
- flukes.
Material for research should be collected in the morning on an empty stomach. 14 days before taking the sample, you need to stop taking antibiotics.
The biomaterial is examined under a microscope and the presence of helminth eggs, larvae, and fragments of adult worms is determined. A negative result of the analysis indicates the absence of worm eggs, and a positive one indicates the presence of invasion.
How informative is such a study? Often there are cases when the analysis gave negative results, but a person has all the signs of helminthiasis. This suggests that at the time of delivery of the biomaterial, the parasites had not yet had time to lay their eggs. Therefore, for an accurate diagnosis, such an analysis is repeated several times.
Extended fecal examination
An extended parasite analysis is more informative than a conventional microscopic examination. Using PCR diagnostics, the presence of parasite DNA in the feces is determined. Such a test shows the presence of helminths at any stage of their life cycle.
The following results may be indicated in the transcript of the analysis:
- Negative. This means that a person has no parasites.
- Positive. Indicates infection with parasitic worms. In this case, the type of helminth is necessarily indicated in the conclusion.
This parasite analysis has its drawbacks. With its help, it is impossible to detect extraintestinal worms. For example, a person may be infected with larvae of a pork tapeworm (cysticercosis). This type of helminth parasitizes in the internal organs and is not found in the feces. In such cases, the presence of parasites can only be detected using a serological blood test.
Analysis of feces for giardiasis
When analyzing for lamblia, feces are examined under a microscope. For such a test, you need to prepare in advance. 14 days before the delivery of the material, foods with fiber should be excluded from the diet, and antibiotics and enterosorbents should be avoided.
Negative results of the analysis indicate the absence of lamblia in the biomaterial, and positive ones indicate the presence of parasites in the feces.
However, false-negative data cannot be ruled out if the patient is not thoroughly prepared for the study. Therefore, a test for lamblia often has to be repeated. At the first analysis, invasion is detected in 72% of cases. The accuracy of the re-study is 90%.
Blood test
A serological blood test for parasites is one of the most accurate diagnostic methods. This test is very sensitive and informative. With its help, you can accurately identify the type of parasite, its localization, as well as to trace the dynamics of invasion. Such a test is prescribed for suspected helminthic infestations (including extraintestinal) and giardiasis.
Blood is taken from a vein for examination. Before submitting biomaterial, the patient is recommended to observe the following rules:
- 8 hours before blood sampling, stop eating. It is allowed to drink only clean water.
- The day before the test for parasites, fatty, spicy and fried foods, as well as alcohol, should be excluded from the diet.
- On the eve of the study, it is necessary to avoid physical and emotional overload.
- 2 weeks before the test, stop taking the medication. If this is not possible, then it is necessary to inform the doctor about the drugs taken.
Detection methods
A blood test for parasites is carried out in the following ways:
- Enzyme immunoassay. This is the most informative diagnostic method. It allows you to determine the presence of antibodies (immunoglobulins) of various groups to parasites. Using this method, it is possible not only to establish the presence of invasion, but also to differentiate the chronic form of helminthiasis from acute.
- The method of polydimensional chain reaction. This method helps to accurately determine the causative agent of the infestation. Using PCR, DNA and RNA parasites can be detected. However, such a study does not allow to determine the stage of the disease.
Blood test transcript
What are the normal rates of enzyme immunoassay for parasites? Test results may be as follows:
- No IgG and IgM antibodies were found in the blood. This suggests that the person is healthy and has no worms and giardia. Such a result is the norm.
- IgM immunoglobulins are present in the biomaterial . This indicator indicates a recent infection and an acute stage of parasitic disease.
- IgG antibodies were detected. This indicates a chronic form of invasion in remission.
- Both types of antibodies were detected: IgM and IgG. Such analysis results are noted with exacerbation of chronic parasitic pathology.
If the study was carried out by PCR, then a negative result is considered the norm. Such data indicate the absence of DNA and RNA helminths in the biomaterial.
A positive result of the study indicates the presence of parasites in the body. The analysis is pretty accurate. It rarely gives false results. Therefore, if the DNA of helminths or protozoa was detected during PCR diagnostics, then it is urgent to start treatment.
Mucus analysis
What tests are given for parasites with suspected enterobiosis? Pinworm infection cannot be detected using standard stool testing. The eggs of these helminths are not found in feces. Only adults can exit the intestines. But this is a rather rare phenomenon, which is observed only with severe infection.
Therefore, if you suspect enterobiosis, doctors prescribe a mucus test. Using a cotton swab, a smear is taken from the area of skin located around the rectum. Pinworms lay eggs in this area.
Nowadays, a more convenient method of this research is also used. A special adhesive tape is used to take the material. It is glued to the area around the anus, and then torn off and taken to the laboratory.
Deciphering the data from this study is very easy. A negative result indicates the absence of pinworm eggs, and a positive result indicates the presence of invasion.
It is important to remember that only enterobiasis can be diagnosed with a smear. No other helminths can be detected in this way.
Other types of tests
As already mentioned, not all types of helminths and protozoa live in the intestines. They can parasitize in any other organs. In this case, they cannot be detected using microscopy or PCR diagnostics of feces. What tests for parasites need to be passed with extraintestinal invasion? The doctor may prescribe the following tests:
- Sputum analysis. With its help, you can detect the presence of such helminths as intestinal acne and pulmonary fluke. The life cycle of such worms proceeds mainly in the respiratory system.
- Analysis of urine. With this study, schistosome eggs can be detected. These helminths parasitize in the urogenital organs.
- Biopsy studies. Some types of tapeworms form blisters (cysts) in the internal organs. In such cases, a piece of the affected tissue is taken for analysis.
- The study of bile. Helps detect flukes and flukes. These helminths live in the liver and gall bladder.
At the same time, an enzyme-linked immunosorbent test is performed to help determine the presence of antibodies. Such a comprehensive examination allows you to identify even those invasions that are difficult to detect by traditional methods, and to start treatment in a timely manner.