Parasitic infections in humans can be detected through blood and stool tests.Different infections have their own diagnostic standards.
Indications for examination for parasites Parasitic infections are not asymptomatic;They always have some symptoms.Therefore, if you have health problems, a blood or stool test for parasites is necessary.If there are no symptoms, no preventive examination is necessary.Symptoms that suggest a parasite infection:
- prolonged rise in temperature to 37-37.5 degrees;
- causeless fatigue;
- a rash on the skin that appears and disappears suddenly;
- Indigestion – rumbling stomach, flatulence, diarrhea;
- detection of anemia;
- Weight loss with normal appetite.
Only in some cases does a person need to be tested for parasites, even if they have no symptoms.This is an examination when applying for a job or when enrolling in a course of study, when obtaining swimming certificates or an examination before an operation.In such cases, a referral for the necessary examinations will be made by a family doctor or pediatrician.
What parasitic infections can be tested for?
Any parasitic infection can be detected using various tests.There are:
- Intestinal parasites – live in the intestinal lumen and excrete eggs in the feces;
- extraintestinal - live in different organs, do not produce eggs.
Intestinal parasites can be identified through a stool analysis, extraintestinal parasites – only through blood.
Opisthorchiasis
Infection by the flatworm Opisthorchis.A person becomes infected by eating river fish - dried or dried, that is, not thermally processed.Opisthorchiasis does not spread between people, meaning the patient is not contagious.However, a sick person excretes parasite eggs in their feces; they get into the water and then into the fish.
Trichinosis
Trichinella are small worms that live in the muscles of pigs and wild animals.A person becomes infected when they eat undercooked or undercooked meat.Trichinella enter the muscles from the intestines and form a capsule there.It is an extraintestinal parasite that can reside in muscles for decades without causing symptoms.A person cannot infect others.
Ascariasis
Roundworms are long roundworms that live in the intestines.Human infection occurs through dirty hands.Roundworms go through two stages of development in the body.Larvae form from the eggs in the intestine and reach the lungs via the bloodstream.Here they live for two months, then they are swallowed with sputum and return to the intestines.Here the roundworms develop into adult worms and release their eggs in the feces.A sick person can infect others if hygiene rules are not followed.
Toxocariosis
Toxocara are parasites of dogs and other dogs.Toxocara eggs are found on animal fur and people become infected through contact with them.After the eggs are swallowed in the intestine, larvae hatch from them, but the worm does not develop further.
The larvae are transported in the blood to various organs and form capsules there.Like trichinella, they can live in tissue 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, where the larvae hatch.They are transported to the organs via the blood, usually in the liver.Cysts form here - bubbles with fluid in which echinococci are located.A person is not contagious to others and does not release parasite eggs into the environment.
Giardiasis
Giardia is the simplest microorganism;Infection occurs through drinking unboiled water through dirty hands.Giardia parasites live in the small intestine and children in particular suffer from giardiasis.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, you need to do a stool or blood test.Intestinal worms and Giardia can be detected through stool analysis;Blood is an auxiliary method.Extraintestinal parasites can only be identified by blood because they do not secrete eggs.
Blood tests for parasites are not 100% accurate.They can be either false positive or false negative.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.Therefore, if you suspect echinococcosis, you must first do an ultrasound scan of the liver.If cysts are found there, donate blood for antibodies to echinococcus.
Parasites extremely rarely live in the kidneys.These are tropical protozoan schistosomes;They become infected while swimming in polluted waters in tropical countries.Parasites in the human bladder can be identified using x-rays to detect antibodies.
Stool analysis for parasites
This analysis is called a stool test for worm eggs and protozoa.The following parasites can be detected with a stool test:
- Opisthorchis;
- roundworms;
- wide tape;
- beef and pork tapeworm;
- strongyloid;
- whipworm;
- Giardia.
A fecal analysis for helminths is not very informative because worms do not always secrete eggs and these do not appear in all samples.To get an accurate result, you need to donate stool at least three times with an interval of 3 days.It is better to examine warm feces.
The Parasep technique is more reliable - this is an examination of feces diluted in a special liquid.The method is also called stool enrichment analysis.Sometimes worm eggs and protozoa are detected in a coprogram - a detailed stool analysis to diagnose digestive disorders.
Modern research for Giardia consists in detecting their antigens in feces using the PCR method.The reliability of the technology is 90-95%.
Scrape
The scraping method only identifies pinworms.These are small worms that live in the large intestine.At night, female worms crawl out and lay eggs on the skin around the anus.The disease caused by pinworms is enterobiasis.
Enterobiasis mainly affects young children.A child can constantly infect himself by scratching the skin near the anus and then putting his hands in his mouth.
The test for pinworms is carried out in the morning without washing the child.A piece of tape is placed on the skin around the anus.It is then glued to a glass slide.A laboratory technician examines the glass under the microscope and discovers pinworm eggs.
Blood sample
A general blood test in the presence of parasites in the body provides indirect signs:
- increase in the number of eosinophils;
- Increase in ESR.
In the acute stage of the disease, the number of eosinophils increases sharply and exceeds 20%.In the chronic stage, the general blood test is practically unchanged.
Antibodies against parasites are detected in the blood using an enzyme immunoassay.The study is suitable for the diagnosis of intestinal helminths and Giardia in the acute stage of the disease, as well as for the identification of extraintestinal helminths.
Types of blood tests for parasites
Blood tests for parasites are the same for adults and children.The study is more meaningful in children because they are more likely to become acutely ill.Chronic helminthiases predominate in adults, so blood tests often give false results.
ELISA
An enzyme immunoassay for parasites is used for diagnosis.This 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 being produced.In the chronic stage, the helminths are masked and the body stops producing antibodies against them.Therefore, the ELISA gives a false negative result.If a person suffers from an allergy or an autoimmune disease, they produce false antibodies and the ELISA result is false positive.
A blood test to detect parasites must be confirmed by other examination methods.
In children
Both tests for parasites - blood and feces - are informative for the child.Children predominantly suffer from acute forms of parasitosis.Stool testing for worms and protozoa is informative in 90% of cases, ELISA in 70% of cases.
How and where can you 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 obtain a referral for a test in a clinic, you must contact a general practitioner, pediatrician or infectious disease specialist.You can do it yourself in any paid laboratory.However, if there are no health problems, an examination is not necessary.Parasitic infections that are asymptomatic (toxocariasis, trichinosis) do not require treatment.It is only prescribed when symptoms appear.