Parasitic infections in humans can be detected through blood and stool tests.Different infections have their own diagnostic standards.
Indications to search for parasites Parasitic infections are not asymptomatic;they still have symptoms.Therefore, you should conduct blood or stool tests to detect parasites if you have health problems.Preventive testing is not required in the absence of symptoms.Suspected symptoms of a parasitic infection:
- prolonged increase in temperature up to 37-37.5 degrees;
- fatigue without cause;
- a rash that appears and disappears suddenly;
- indigestion – stomach rumbling, gas, diarrhea;
- anemia detection;
- weight loss with normal appetite.
Only in certain cases should a person be tested for parasites, even if they do not complain.This is an examination when applying for a job or registering for studies, obtaining a swimming certificate or an examination before a surgical procedure.In such cases, a referral for the required examinations is given by a general practitioner or pediatrician.
What parasitic infections can we detect?
Through various tests, any parasitic infection can be detected.There is:
- intestinal parasites – live in the intestinal lumen and excrete eggs in the stool;
- 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 Opisthorchis flatworm.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 excretes parasite eggs in their stool, they enter the water and then into 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.Trichinellae from the intestines penetrate the muscles and form a capsule there.It is an extraintestinal parasite that can reside in muscles for decades without causing symptoms.One person cannot infect others.
Ascariasis
Roundworms are long, round worms 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 that 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 their eggs in the stool.A sick person can contaminate others if hygiene rules are not followed.
Toxocariasis
Toxocara are parasites of dogs and other canines.Toxocara eggs are found on the fur of animals and humans become infected through contact with them.After swallowing the eggs in the intestine, larvae emerge, but the worm no longer develops.
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 showing symptoms.The patient is not contagious and does not release Toxocara eggs into the environment.
Echinococcosis
Echinococci are parasites that live in the bodies of dogs.A person becomes infected through contact with an animal.Echinococcus eggs enter the intestines, where the larvae emerge.They are carried by the blood to the organs, most often living in the liver.Here they form cysts - bubbles containing fluid, 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 it is mainly children who suffer from giardiasis.The patient excretes Giardia in the stool and infects others if personal hygiene is not followed.
Types of Tests for Parasites
To identify parasites in the body, you need to do a stool or blood test.Intestinal helminths and Giardia can be determined by stool analysis;blood is an auxiliary method.Extraintestinal parasites are only identified by blood, as they do not secrete eggs.
Blood tests to detect parasites are not 100% accurate.They can be either 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 a liver ultrasound.If cysts are detected there, donate blood for antibodies to echinococcus.
Parasites extremely 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 to detect parasites
This analysis is called a stool test for helminth eggs and protozoa.A stool test can identify the following parasites:
- opisthorchis;
- roundworms;
- wide ribbon;
- bovine and porcine tapeworm;
- strongyloid;
- whipworm;
- Giardia.
Fecal analysis for helminths is not very informative, since the worms do not secrete eggs all the time and they are not found in all samples.To obtain an accurate result, you need to give stools at least three times with an interval of 3 days.It is best to examine warm stools.
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 stool to diagnose digestive disorders.
Modern research on Giardia involves detecting their antigens in feces using the PCR method.The technique has a reliability of 90 to 95%.
Scraping
Thanks to the scraping method, only pinworms are identified.These are small worms that live in the large intestine.At night, female worms crawl and lay eggs on the skin around the anus.The disease caused by pinworms is enterobiasis.
Enterobiosis 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 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 in the presence of parasites in the body gives indirect signs:
- increased 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 the blood to detect parasites, antibodies to them are detected.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 to detect parasites are the same in adults and children.In children, the study is more informative, since they are more often sick in an acute form.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 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 stage, helminths become masked and the body stops producing antibodies against them.The ELISA therefore 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 aimed at detecting parasites must be confirmed by other examination methods.
In children
Both tests for parasites - blood and stool - will be informative for the child.Children mainly suffer 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 take a blood test to detect parasites
You can undergo an examination in a clinic at your place of residence or in a paid laboratory.To get a referral for a test in a clinic, you must contact a general practitioner, pediatrician or infectious disease specialist.You can take it yourself at 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 only prescribed when symptoms appear.