Parasitic infections in humans can be detected through blood and stool tests.Different infections have their own diagnostic standards.
Indications for Parasitic Testing Parasitic infections are not asymptomatic;they always have some symptoms.Therefore, you should take blood or stool tests for parasites if you have health problems.In the absence of symptoms, preventive tests are not required.Suspicious symptoms for a parasitic infection:
- prolonged increase in temperature to 37-37.5 degrees;
- causeless tiredness;
- a rash that appears and disappears suddenly;
- indigestion - rumbling in the stomach, gas, diarrhea;
- anemia detection;
- weight loss with normal appetite.
Only in some cases is it necessary to test a person for parasites, even if he has no complaints.This is an exam when applying for a job or enrolling in studies, obtaining swimming certificates or being examined before surgery.In these cases the referral for the required tests is given by the general practitioner or paediatrician.
What parasitic infections can you test for?
Using various tests, any parasitic infection can be detected.There are:
- intestinal parasites: they live in the intestinal lumen and expel their eggs in the feces;
- extraintestinal: lives in various organs, does 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 heat-treated.Opisthorchiasis does not spread between people, that is, the patient is not contagious.However, a sick person expels the eggs of the parasite in the feces, they enter the water and then into the fish.
Trichinosis
Trichinae 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 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 others.
Ascariasis
Roundworms are long roundworms that live in the intestine.Human infection occurs through dirty hands.In the body, roundworms go through two stages of development.In the intestine, larvae are formed from eggs, which enter the lungs through the bloodstream.Here they live for two months, then are swallowed with sputum and return to the intestine.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.
Toxocariasis
Toxocara are parasites of dogs and other canids.Toxocara eggs are found on animal fur, and humans become infected through contact with them.After swallowing the eggs into the intestine, the larvae emerge, but no further development of the worm occurs.
The larvae are transported with the blood to the various organs and form capsules inside them.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 intestine, where the larvae emerge.They are transported through the blood to the organs, most often living in the liver.Here they form cysts - bubbles with liquid, inside 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 by drinking unboiled water with dirty hands.Giardia parasites live in the small intestine and especially 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 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 helminths themselves to camouflage.
Some parasitic infections require an ultrasound or x-ray.So, if you suspect echinococcosis, you must first do an ultrasound of the liver.If cysts are found there, donate blood for antibodies against echinococci.
Parasites live in the kidneys very rarely.These are schistosomes of tropical protozoans;they become infected by swimming in the polluted waters of tropical countries.Parasites in the human bladder can be identified using x-ray to detect antibodies.
Stool analysis for parasites
This analysis is called a stool test for helminth and protozoan eggs.A stool test can identify the following parasites:
- opistorchi;
- nematodes;
- wide ribbon;
- bovine and porcine tapeworms;
- strongyloide;
- whipworms;
- Giardia.
Stool analysis for helminths is not very informative, since worms do not always secrete eggs and are not found in all samples.To get an accurate result, you need 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: it 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 feces 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%.
Scrape
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 self-infect by constantly scratching the skin near the anus and then putting his hands in his mouth.
The test for pinworms is performed in the morning without washing the child.A piece of tape is applied to the skin around the anus.It is then glued onto a glass slide.A laboratory technician examines glass under a microscope and discovers pinworm eggs.
Blood tests
A general blood test in the presence of parasites in the body gives indirect signs:
- increased number of eosinophils;
- increase in ESR.
In the acute phase of the disease, the number of eosinophils increases significantly, exceeding 20%.In the chronic phase, the general blood test is 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, since they are more often sick in acute form.In adults, chronic helminthiasis predominates, so blood tests often give false results.
ELISA
An enzyme immunoassay for parasites is used for diagnosis.This is the detection of antibodies to helminths and protozoa in the blood.ELISA is most informative in the acute phase of the disease, when antibodies are actively produced.In the chronic stage, helminths disguise themselves 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 methods of examination.
In children
Both tests for parasites - blood and feces - will be informative for the child.Children mainly suffer from acute forms of parasitosis.Stool examination 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 undergo a test at a clinic in your place of residence or in a paid laboratory.To get a referral for testing at a clinic, you need to contact a primary care physician, pediatrician, or infectious disease specialist.You can take it yourself to any paid laboratory.But if there are no health problems, there is no need to get checked.Asymptomatic parasitic infections (toxocariasis, trichinosis) do not require treatment.It is prescribed only when symptoms appear.