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, you need to take blood or stool tests for parasites if you have health complaints.Preventative testing is not required in the absence of symptoms.Symptoms suspicious for a parasitic infection:
- prolonged increase in temperature to 37-37.5 degrees;
- causeless fatigue;
- a rash on the skin that suddenly appears and disappears;
- indigestion - rumbling in the stomach, gas, diarrhea;
- detection of anemia;
- weight loss with normal appetite.
Only in some cases does a person need to be tested for parasites, even if he has no complaints.This is an examination when applying for a job or enrolling in studies, obtaining certificates for swimming, or examination before surgery.In such cases, a referral for the required tests is given by a general practitioner or pediatrician.
What parasitic infections can be tested for?
Using various tests, any parasitic infection can be detected.There are:
- intestinal parasites - live in the intestinal lumen and excrete eggs in the feces;
- extraintestinal - live in various organs, do not produce eggs.
Intestinal parasites can be identified by stool analysis, extraintestinal parasites - only by blood.
Opisthorchiasis
Infection caused 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, that is, the patient is not contagious.However, a sick person excretes parasite eggs in his 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 if he eats undercooked or undercooked meat.Trichinella from the intestines enter the muscles and form a capsule there.It is an extraintestinal parasite that can reside in muscles for decades without causing any symptoms.A person cannot infect others.
Ascariasis
Roundworms are long roundworms that live in the intestines.Human infection occurs through dirty hands.In the body, roundworms go through two stages of development.In the intestines, larvae form from the 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 roundworms 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 on animal fur, and humans become infected through contact with them.After swallowing the eggs in the intestine, larvae emerge from them, but no further development of the worm occurs.
The larvae are carried with the blood to different organs and form capsules in them.Like Trichinella, they can live in tissues for many years without giving 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 emerge.They are carried through the blood to organs, most often living in the liver.Here they form cysts - bubbles with liquid, inside of which there are echinococci.A person is not infectious to others and does not release parasite eggs into the environment.
Giardiasis
Giardia is the simplest microorganism; infection occurs by drinking unboiled water through dirty hands.Giardia parasites live in the small intestine, and predominantly children suffer from giardiasis.The patient excretes Giardia in the feces and infects others if personal hygiene is not observed.
Types of tests for parasites
To identify parasites in the body, you need to take 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 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.So, if you suspect echinococcosis, you first need to do an ultrasound of the liver.If cysts are found there, donate blood for antibodies to echinococci.
Parasites live in the kidneys extremely rarely.These are tropical protozoa schistosomes; they become infected by swimming in polluted waters of tropical countries.Parasites in the human bladder can be identified using radiography to detect antibodies.
Stool analysis for parasites
This analysis is called a stool test for helminth eggs and protozoa.A stool test can identify the following parasites:
- opisthorchis;
- roundworms;
- wide tape;
- bovine and pork tapeworm;
- strongyloid;
- whipworm;
- Giardia.
Fecal analysis for helminths is not very informative, since worms do not secrete eggs all the time, and they are not found 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 a study of feces diluted in a special liquid.The method is also called stool enrichment analysis.Sometimes helminth eggs and protozoa are detected in a coprogram - a detailed analysis of stool to diagnose digestive disorders.
Modern research for Giardia is the detection of their antigens in feces using the PCR method.The technique has a reliability of 90-95%.
Scraping
Using the scraping method, only pinworms are identified.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 self-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 adhesive 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;
- increase in ESR.
In the acute stage of the disease, the number of eosinophils increases sharply, exceeding 20%.In the chronic stage, the general blood test is practically unchanged.
Using an enzyme immunoassay in blood for parasites, antibodies to them are detected.The study is suitable for diagnosing intestinal helminths and Giardia in the acute stage 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 are more often ill in an acute form.In adults, chronic helminthiases predominate, so blood tests often give false results.
ELISA
For diagnosis, an enzyme immunoassay for parasites is used.This is the detection of antibodies to 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 become masked 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, he will form false antibodies and the ELISA result will be false positive.
A blood test to detect parasites must be confirmed by other examination methods.
In children
Both tests for parasites - blood and feces - will be informative for the child.Children suffer predominantly from acute forms of parasitosis.Examination of stool 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 at a clinic at your place of residence or in a paid laboratory.To get a referral for testing at a clinic, you need to contact a general practitioner, pediatrician or infectious disease specialist.You can take it yourself in any paid laboratory.But if there are no health complaints, it is not necessary to get checked.Parasitic infections that are asymptomatic (toxocariasis, trichinosis) do not require treatment.It is prescribed only when symptoms appear.