Toxocariasis is a zoonotic parasitic disease, helminthiasis. It is caused by roundworms nematodes, outwardly similar to human roundworms. The disease has various forms, a long course with frequent relapses.
The number of worms in the body determines the severity of the disease. Children (from 1 to 4 years old) get sick more often due to their habits - putting everything in their mouths, rummaging and playing in sandboxes, stroking and kissing pets, etc. They also do not have a special love for washing their hands.
The spread of toxocariasis is widespread. In humans, larval and imaginal toxocariasis occurs more often. In the second case - the intestinal form, the rest are larval.
What is Toxocara?
Toxocara is a worm that parasitizes in the body of dogs. A person for him is an accidental host, and in his body the helminth does not develop to an adult, only to larvae. The duration of his life in the human body is a maximum of 6 months. But the larvae cause disease with all its manifestations.
Reproduction is happeningvery quickly, because females lay up to 200 thousand eggs per day. The sexually mature helminth is dioecious, has a reddish color, a fairly long body (up to 18-20 cm long, 2-3 mm wide).
In this form, they reside in the intestines of dogs, wolves, foxes - a species of Toxocaracanis, as well as cats - Toxocaracat. Only dog worms are dangerous to people.
Toxocariasis in humans is accompanied by damage to the liver, lungs, central nervous system, organs of vision. Helminths form granulomas in them with larvae inside. In them, the larvae are viable for several years.
Routes of infection
The main source of infection is sick dogs. Toxocariasis is not transmitted from a sick person. Transmission is possible through contact with a sick dog, especially a puppy that has worm eggs on its coat.
The route of infection is fecal-oral. There are up to 15 thousand eggs per 1 g of feces. The main reason is poor hygiene. Toxocara eggs are in the ground and penetrate a person through poor personal hygiene, dirty food, etc.
It is important to note that eggs need to mature in the soil within a month.
Adults get sick less often, with the exception of some professions: cynologists, veterinarians, dog breeders, hunters. Toxocariasis can begin to destroy organs even years after infection.
Infection sequence
In dogs, the larvae can penetrate the placenta of females into the fetus and develop there. ATAs a result, puppies are born already infected with worms. From eggs in the intestines of a person, larvae appear. They are able to penetrate through the walls of the intestine into the blood and through the vessels to reach any organs or tissues. There they are encapsulated and retain their biological activity for a long time.
As for the larvae of cat Toxocara, after migrating through the body, they again reach the intestines in the adult stage, which leads to the imaginal form of the disease.
Mechanism of infection
Infection occurs at any time of the year, but more often in the autumn-summer period. Toxocara eggs enter the oral cavity, through the stomach they reach the intestines, where the larvae emerge from them. They enter the bloodstream and then the liver. Part of the parasites through the portal vein system reaches the right half of the heart and lungs. In the same place, some part continues the journey to other organs, occupying them. They can settle in the brain, thyroid gland, kidneys, muscles. Here they live for a long time, periodically renewing their migration and provoking relapses.
The larvae damage the internal organs and die themselves, leaving inflammation, necrosis, hemorrhages. Even cured toxocariasis can reappear.
Antibody production
During migration, blood vessels are injured with the development of inflammation and necrosis. Toxocara sensitize the body and in this case play the role of antigens. The immune system reacts by producing antibodies to toxocara. It is an immunoglobulin protein. Allergic reactions develop immediately and delayed.
Theymanifest as skin erythema, edema, asthma attacks. In the blood, the number of eosinophils sharply increases, which are attracted by the resulting immune complexes to the lesion. Thus, what does antibodies to toxocara or AT mean? AT is an indicator of parasitic worm infection.
Course of disease
The course of toxocariasis is divided into several types:
- Asymptomatic type - no complaints or clinical manifestations.
- Latent type - coughs, migraines and abdominal pain.
- Localized is subdivided into ocular, cutaneous, visceral and neurological.
- Systemic, affecting several organs at once.
Acute toxocariasis is initially manifested by a slight fever, malaise, myalgia, swollen lymph nodes and allergic reactions.
With latent toxocariasis, the symptoms are meager and faded, the disease is detected only in the laboratory. Chronic pathology combines both forms. They talk about it when there was an acute attack, then a remission, then an exacerbation again, etc.
Symptomatic manifestations
Allergic skin symptoms are most pronounced - this is the skin form. It is accompanied by hepatosplenomegaly, fever, bronchopneumonia with asthma attacks and coughing, swelling of the face, and the formation of granulomas in various body systems.
Main symptoms of visceral toxocariasis:
- hepatosplenomegaly;
- fever;
- bronchopneumonia with cough up to suffocation;
- puffy face;
- formation in various organs of specific granulomas in which the larvae are located.
Develops with a large number of larvae. Lung damage can lead to asthma.
With neurological toxocariasis, the brain is affected and mental disorders occur, while there are:
- hyperactivity;
- convulsions;
- decrease in attention and memory;
- paresis and paralysis.
For the development of ocular toxocariasis, a small number of larvae is sufficient, this form lasts for several years. It affects more often adults. Only 1 eye is affected.
The larvae infect the retina and choroid of the eye, causing purulent inflammation here.
May occur:
- strabismus;
- leukorrhea;
- optic neuritis;
- keratitis;
- vitreous abscess;
- reduction of vision up to blindness.
Imaginal toxocariasis is rare. Manifested by nausea, abdominal pain, hypersalivation, dizziness and loss of appetite.
Complications and consequences
Action on the main body systems:
- Respiratory organs - asthma, fatal pneumonia.
- From the side of the central nervous system - convulsions, paresis and paralysis.
- Eye damage leads to sepita.
- Myocarditis.
Diagnostic measures
The diagnosis of "toxocariasis" is based on the clinic, epidemiological history and laboratory results. Identification is complicated by the fact that neither eggs nor larvae can be found in the feces. Only in the intestinal form can the eggs be in the stool.
Since the body is sensitized, after infection, class G immunoglobulins can be detected after 1.5-2 months. After 3 months, their concentration in the blood is maximum, then the concentration remains stable for a long period.
The main indicator is a blood test for antibodies. An analysis for antibodies to toxocara is a serological reaction with a toxocara antigen. Immunoglobulin IgG has tasks:
- detection of a foreigner in the blood;
- bonding with an antigen and creating immunity against it - an antibody.
If properly prepared, ELISA will show IgG antibodies to toxocara antigens.
The amount of IgG antibodies in the blood is measured by titers. If the antibody titer is above normal, then the diagnosis is confirmed.
The transcript will be as follows:
- Antibodies to toxocara norm - titer 1:100 - does not confirm the diagnosis; a person may be a carrier.
- Titer 1:400 - toxocars are present in the body, but do not progress; this is characteristic of the eye form.
- Titer 1:600 (800) – antibodies to Toxocara were detected, the parasites are present in the body, they manifest themselves in an acute form.
If the readings are higher than 1:800, it means that parasites of another species are also present in the body. Then you can take the feces for analysis to detect other helminths.
To determine the presence of antibodies to toxocara in the body, the complement binding reaction (RCC) is also used -also a serological test.
Blood test will show:
- persistent long-term eosinophilia (up to 70-90%) and ESR up to 50 mm/h;
- leukocytosis is an indicator of the presence of inflammation;
- low hemoglobin - anemia.
Biochemical analysis may reveal the following disorders:
- hyperglobulinemia;
- hyperbilirubinemia, which provokes the breakdown of red blood cells.
Additionally, X-ray, ultrasound, MRI of damaged organs may be needed.
Several decades ago, a special table was developed for doctors of the significance of clinical signs and laboratory results by points.
Toxocariasis is diagnosed with a total score of 12 or more.
Possible results of ELISA diagnostics
The class and number of detected antibodies determine the question of the etiology of the infection (whether it exists or not), its acute or chronic stage at the time of the examination. They are produced by lymphocytes whenever a pathogen enters the body.
There are several classes of immunoglobulins, the most studied are 5: A (IgA), E (IgE), M (IgM), G (IgG), D (IgD). They differ not only in the weight and structure of the molecules, but also in the degree of participation in the processes of the disease, the timing of detection from the moment of infection.
IgM has the highest molecular weight and cannot cross the placenta.
In a 1-year-old child, the detection of IgM indicates the presence of an infection. In blood serum, up to 85% is IgG, and the smallest% is IgE(0.003%). Only IgA, M, G are involved in the infectious process.
IgG antibodies are the most reliable sign of toxocariasis. In the analysis, total antibodies to toxocara IgG class are determined. All their data is entered in a special table with the application of quantitative indicators.
Preparing for analysis
A blood test for antibodies to Toxocara is taken in the morning on an empty stomach from a vein. One day before the sampling is not allowed:
- drink alcohol;
- take antibiotics;
- to allow physical activity.
No food restrictions.
Transcript
What does toxocara antibodies mean? These are indicators of the presence of parasites in the body. Helps to identify the type of parasite.
A negative blood test for toxocara antibodies can cause ocular toxocariasis when the immune response is weak or infection occurs too early.
False positive reactions are possible in the following cases:
- bearing;
- hormonal failure;
- cancer, cirrhosis.
Additional tests may be ordered.
Practice shows that the severity of the disease does not always correspond to a high level of antibodies to toxocara. Those infected are monitored, and in case of clinical manifestations of toxocariasis, treatment is prescribed.
Principles of treatment
Treatment with anti-nematode drugs:
- "Tiabendazole" ("Mintezol");
- Albendazole;
- Vermox("Mebendazole");
- Medamin.
They are only effective for free-swimming larvae. They have no effect on granulomas. Their efficiency is 50%. Therefore, it often becomes necessary to repeat the treatment.
Prevention measures
Prevention is associated with personal hygiene, sufficient heat treatment of products, especially meat; destruction of flies - carriers of infections. A routine examination of pets is also required.
