Parasitic infections in humans can be detected through 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, you need to have blood or stool tests done to detect parasites if you have health problems.Preventative testing is not necessary in the absence of symptoms.Symptoms suspected of parasitic infection:
- prolonged increase in temperature to 37-37.5 degrees;
- causeless fatigue;
- a rash that appears and disappears suddenly;
- indigestion - stomach rumbling, gas, diarrhea;
- anemia detection;
- weight loss with normal appetite.
Only in some cases does a person need to be tested for parasites, even if they have no complaints.This is an exam to apply for a job or enroll in studies, obtain swimming certificates or exam before surgery.In these cases, referral for the requested tests is made by a general practitioner or pediatrician.
What parasitic infections can be tested for?
Using several tests, any parasitic infection can be detected.There is:
- 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 fecal analysis, extraintestinal parasites - only by blood.
Opisthorchiasis
Infection caused by the flatworm Opisthorchis.A person becomes infected by eating river fish - dried or dehydrated, 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 feces, which go 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 they eat undercooked or undercooked meat.Trichinella from the intestine enters the muscles and forms a capsule there.It is an extraintestinal parasite that can reside in muscles for decades without causing any symptoms.A person cannot infect other people.
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 eggs, which enter the lungs through the bloodstream.Here they live for two months, then they are swallowed with sputum and return to the intestine.Here the roundworms transform 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 the skin of animals and humans become infected through contact with them.After swallowing the eggs into the intestine, larvae emerge from them, but no further development of the worm occurs.
The larvae are transported with the blood to different organs and form capsules in them.Like trichinella, they can live in tissues for many years without showing symptoms.The patient is not contagious and does not release Toxocara eggs into the environment.
Echinococcosis
Echinococci are parasites that live in dogs' bodies.A person becomes infected through contact with an animal.Echinococcus eggs enter the intestine, where larvae emerge.They are carried by the blood to organs, usually living in the liver.Here they form cysts - bubbles with liquid, inside 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 when drinking unboiled water with dirty hands.Giardia parasites live in the small intestine and predominantly children 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 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, as 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 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 to obtain antibodies against echinococci.
Parasites rarely live in the kidneys.These are tropical protozoan schistosomes;they become infected by swimming in polluted waters in 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:
- opistorchis;
- roundworms;
- wide ribbon;
- 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 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 best 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 and protozoan eggs are detected in a coprogram - a detailed analysis of feces to diagnose digestive disorders.
Modern research for Giardia consists of detecting its antigens in feces using the PCR method.The technique has a reliability of 90-95%.
Scraping
Using the scraping method, only worms are identified.These are small worms that live in the large intestine.At night, female worms crawl and lay eggs in the skin around the anus.The disease caused by worms is enterobiasis.
Enterobiasis mainly affects young children.A child can self-infect by constantly scratching the skin near the anus and then putting their hands in their mouth.
The test for worms is carried out 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 lab technician examines the glass under a microscope and discovers pinworm eggs.
Blood test
A general blood test for the presence of parasites in the body gives indirect signs:
- increase in the number of eosinophils;
- increase in ESR.
In the acute phase of the disease, the number of eosinophils increases markedly, exceeding 20%.In the chronic phase, the general blood test remains practically unchanged.
Using an enzyme immunoassay in the blood for parasites, antibodies against them are detected.The study is suitable for the diagnosis of intestinal helminths and Giardia in the acute phase 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 in adults and children.In children, the study is more informative, as they are more likely to become acutely ill.In adults, chronic helminthiasis predominates, which is why blood tests often give false results.
ELISA
For diagnosis, an enzyme immunoassay for parasites is used.This is the detection of antibodies against helminths and protozoa in the blood.ELISA is most informative in the acute phase of the disease, when antibodies are being actively produced.In the chronic phase, 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 autoimmune disease, they 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 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 take a blood test for parasites
You can take 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 do this yourself in any paid laboratory.But if there are no health complaints, examinations are not necessary.Asymptomatic parasitic infections (toxocariasis, trichinosis) do not require treatment.It is prescribed only when symptoms appear.