Parasitic infections in humans can be detected by blood and stool tests.Different infections have their own diagnostic standards.
Indications for Parasite Examination Parasitic infections are not asymptomatic;They always have some symptoms.Therefore, if you have health problems, you should have your blood or stool tested for parasites.Preventive tests are not required in the absence of symptoms.Suspected symptoms of a parasitic infection:
- prolonged increase in temperature to 37-37.5 degrees;
- fatigue without cause;
- a skin rash that comes and goes suddenly;
- indigestion: rumbling in the stomach, gas, diarrhea;
- detection of anemia;
- Weight loss with normal appetite.
Only in some cases is it necessary for a person to be tested for parasites, even if they have no complaints.This is a test when applying for a job or enrolling in school, obtaining swimming certificates, or a test before surgery.In such cases, a general practitioner or pediatrician will refer you for the necessary tests.
What parasitic infections can be tested for?
Any parasitic infection can be detected through various tests.There is:
- intestinal parasites: they live in the intestinal lumen and excrete eggs in the feces;
- extraintestinal: lives in several organs, does not produce eggs.
Intestinal parasites can be identified by stool analysis, extraintestinal parasites only by blood analysis.
opisthorchiasis
Infection caused by the Opisthorchis flatworm.A person becomes infected by eating river fish, dried or dried, that is, not thermally processed.Opisthorchiasis is not transmitted between people, that is, the patient is not contagious.However, a sick person excretes parasite eggs in their feces, which reach the water and then the fish.
trichinosis
Trichinella are small worms that live in the muscles of pigs and wild animals.A person becomes infected if they eat undercooked or undercooked meat.Trichinella from the intestines enters the muscles and forms a capsule there.It is an extraintestinal parasite that can reside in the muscles for decades without causing any symptoms.A person cannot infect others.
ascariasis
Nematodes are long nematodes that live in the intestines.Human infection occurs through dirty hands.In the body, nematodes go through two stages of development.In the intestines, larvae are formed from eggs, which enter the lungs through the bloodstream.Here they live for two months, then they are swallowed with sputum and return to the intestines.Here the nematodes develop into adult worms and release eggs in the feces.A sick person can infect others if hygiene rules are not followed.
toxocariasis
Toxocara are parasites of dogs and other canines.Toxocara eggs are found in the fur of animals and humans become infected by coming into contact with them.After swallowing the eggs in the intestine, larvae emerge, but the worm does not develop further.
The larvae are transported with the blood to different organs and form capsules there.Like Trichinella, they can live in tissues for many years without causing symptoms.The patient is not contagious and does not release Toxocara eggs into the environment.
echinococcosis
Echinococci are parasites that live in the body of dogs.A person becomes infected through contact with an animal.Echinococcus eggs enter the intestines, from where the larvae emerge.They are carried through the blood to organs and most often live in the liver.Cysts, bubbles with liquid, form here, inside which echinococci are found.A person does not infect others and does not release parasite eggs into the environment.
giardiasis
Giardia is the simplest microorganism;Infection occurs when drinking unboiled water with dirty hands.Giardia parasites live in the small intestine and giardiasis is mainly suffered by children.The patient excretes Giardia in feces and infects others if personal hygiene is not observed.
Types of tests for parasites
To identify parasites in the body, it is necessary to perform a stool or blood test.Intestinal helminths and Giardia can be determined by stool analysis;blood is an auxiliary method.Extraintestinal parasites are identified only by blood, since they do not secrete eggs.
Blood tests for parasites are not 100% accurate.They can be false positives or false negatives.The reasons for false results are the characteristics of the body, the presence of allergies, concomitant diseases and the ability of the helminths themselves to camouflage themselves.
Some parasitic infections require an ultrasound or x-ray.So, if you suspect echinococcosis, you should first do an ultrasound of the liver.If cysts are found there, donate blood to obtain antibodies against echinococci.
Parasites live in the kidneys very rarely.These are schistosomes of tropical protozoans;They become infected by swimming in contaminated waters in tropical countries.Parasites in the human bladder can be identified by x-ray to detect antibodies.
Analysis of feces for parasites.
This analysis is called a stool test for helminth and protozoan eggs.A stool test can identify the following parasites:
- opisthorchis;
- intestinal worms;
- wide ribbon;
- had bovine and pork;
- strongyloid;
- whipworm;
- Giardia.
Analysis of feces for helminths is not very informative, since worms do not secrete eggs all the time and are not found in all samples.To obtain an accurate result, it is necessary to donate feces at least three times with an interval of 3 days.It is better to examine hot stools.
The Parasep technique is more reliable: this is a study of feces diluted in a special liquid.The method is also called stool enrichment analysis.Sometimes helminth eggs and protozoa are detected by a coprogram - a detailed analysis of feces to diagnose digestive disorders.
Modern research on Giardia is the detection of its antigens in feces using the PCR method.The technique has a reliability of 90-95%.
Scraping
With the scraping method, only pinworms are identified.They are small worms that live in the large intestine.At night, the female worms come out and lay eggs in the skin around the anus.The disease caused by pinworms is enterobiasis.
Enterobiasis mainly affects young children.A child can constantly become self-infected by scratching the skin near the anus and then putting his hands in his mouth.
The pinworm test is done in the morning without washing the child.A piece of tape is applied to the skin around the anus.It is then glued to a glass slide.A laboratory technician examines the glass under a microscope and discovers pinworm eggs.
Blood test
A general blood test in the presence of parasites in the body gives indirect signs:
- increase in the number of eosinophils;
- increased ESR.
In the acute stage of the disease, the number of eosinophils increases sharply, exceeding 20%.In the chronic stage, the general blood test practically does not change.
Using an enzyme immunoassay in blood to detect parasites, antibodies against them are detected.The study is suitable for diagnosing intestinal helminths and Giardia in the acute phase of the disease, as well as for identifying extraintestinal helminths.
Types of blood tests for parasites.
Blood tests for parasites are the same in adults and children.In children, the study is more informative, since they often become acutely ill.Chronic helminthiasis predominates in adults, which is why blood tests often give false results.
ELISA
An enzyme immunoassay for parasites is used for diagnosis.It involves the detection of antibodies against helminths and protozoa in the blood.ELISA is most informative in the acute stage of the disease, when antibodies are actively produced.In the chronic phase, helminths mask themselves and the body stops producing antibodies against them.Therefore, ELISA gives a false negative result.If a person has an allergy or an autoimmune disease, they will form false antibodies and the ELISA result will be a false positive.
A blood test for parasites must be confirmed by other examination methods.
in children
Both parasite tests (blood and stool) will be informative for the child.Children predominantly suffer from acute forms of parasitosis.Examination of feces for worms and protozoa is informative in 90% of cases, ELISA - in 70% of cases.
How and where to get a blood test for parasites.
You can undergo an examination in a clinic at your place of residence or in a paid laboratory.To get a referral for testing at a clinic, you should contact a family doctor, pediatrician, or infectious disease specialist.You can do it yourself in any paid laboratory.But if there are no health problems, it is not necessary to have checks.Asymptomatic parasitic infections (toxocariasis, trichinosis) do not require treatment.It is prescribed only when symptoms appear.