Toxocara canis, IgG antibodies
Why this test?
The study is conducted to detect infection with a nematode of the Anisakidae family, genus Tohosara canis, which causes toxocarosis. Examination of people belonging to risk groups is recommended: veterinarians, animal breeders, dog breeders, children with signs of fever of unknown origin and blood eosinophilia.
There are several methods that can be used to test for toxocariasis. One of them allows you to determine the antibodies of the pathogen in the blood. When a person comes in contact with Toxocara canis, their immune system responds by producing IgM and IgG antibodies. Immunoglobulins of class G to Toxocara appear in the blood in 6-8 weeks from the moment of infection. Their concentration increases and after 2-3 months reaches a maximum, remaining at a certain level for a long time.
The degree of increase in the level of antibodies in the blood is closely related to the severity of the disease. False positive test results are possible in persons with systemic lymphoproliferative diseases and immunodeficiency.
False-negative and questionable test results can be observed in people with eye damage as a result of weak antigenic exposure. The test for antibodies of the IgG class to Toxocara is the main method of detecting toxocariasis in humans and is used to confirm the diagnosis.
In what cases is it prescribed?
If there are signs of damage to the liver, lungs and / or fever of unknown origin against the background of eosinophilia in the blood, indicating a possible invasion by nematodes.
With a sudden decrease in vision affecting one eye.
According to epidemiological indicators (contact with dogs, earth - especially in children).
If a person is known to have consumed undercooked foods that may have been contaminated with T. Canis.
When the patient belongs to the group of increased risk (animal breeders, dog breeders, farmers, veterinarians).
The study is conducted to detect infection with a nematode of the family Anisakidae of the genus Tohosara canis - these are roundworms that cause toxocariasis. Toxocarosis is a worldwide parasitic disease that affects various organs, including the eyes.
The main host (source of infection) is domestic and wild animals of the canine family (dogs, wolves, foxes, etc.), infected with T. canis. The infection rate of these animals in our country is up to 70%. In their body, the final maturation of the parasite into adults takes place, which are localized in the small intestine and produce eggs that are released into the environment with feces. When helminth eggs fall into the soil, they remain viable and invasive for a long time.
Humans become infected by ingesting T. Canis eggs found in the soil, on animal fur, and by eating undercooked food. Once inside, the larvae of the parasite begin to emerge from the eggs in the proximal part of the small intestine. Then they migrate through the intestinal mucosa into the circulatory system and enter the liver through the portal vein, where they partially settle. The rest of the larvae that have passed through the liver enter the lungs through a small circle of blood circulation, where they also partially settle. Toxocar larvae that have passed through the lungs spread throughout the body through a large circle of blood circulation, settling in various organs.
Larvae of helminths that have got into the tissues of organs do not undergo further normal development and ultimately die there, encapsulate and form granulomas. Migrating through the body, the larvae have different effects on it: they injure blood vessels, causing bleeding and necrosis. Excretory-secretory antigens of larvae, which have a sensitizing effect on the body, are of great importance. The severity of clinical manifestations of the disease is related not only to the number of parasites, but also to the level of allergic sensitivity of the body. With toxocarosis, the liver, lungs, central nervous system, including eyes, kidneys and skeletal muscles are most often affected. Toxocarosis can occur in various forms, often without symptoms. Clinically, 2 forms are distinguished: visceral syndrome - wandering larva syndrome - and ocular toxocarosis.
The main symptoms of infection with T. canis: fever, lymphadenopathy, general malaise, skin rash, gastrointestinal disorders, with massive invasions - pain in the right hypochondrium, enlargement of the liver and spleen, signs of lung damage. The ocular form of toxocariasis is characterized by damage to one eye in the form of reduced visual acuity, retinal granuloma, uveitis, endophthalmitis, optic neuritis, keratitis, or the presence of migrating larvae in the vitreous body.
Although the main manifestations of the disease depend on the affected organs, the most characteristic laboratory indicator is peripheral blood eosinophilia. In patients with reduced immunity, a massive invasion by toxocars can cause a serious complication. The diagnosis of toxocarosis is made on the basis of the clinical picture, eosinophilia, data from the epidemiological history and the results of a serological examination.