Toxocariasis is a zoonotic parasitic disease, helminthiasis. Called by roundworms, nematodes that look like human roundworms. The disease has various forms, a prolonged 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 - pull everything in their mouths, rummage and play in sandboxes, pet and kiss pets, etc. They also don’t have a special love for washing their hands.
The spread of toxocariasis is widespread. In humans, larval and imaginal toxocariasis more often occurs. 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. Man for him is a random 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 the disease with all its manifestations.
Reproduction occurs very quickly, because females lay up to 200 thousand eggs per day. The sexually mature helminth is dioecious, has a reddish color, a rather long body (up to 18-20 cm in length, 2-3 mm in width).
In this form, they are in the intestines of dogs, wolves, foxes - the species Toxocaracanis, as well as cats - Toxocaracat. Only dog worms are dangerous to humans.
Toxocariasis in humans is accompanied by damage to the liver, lungs, central nervous system, and organs of vision. Helminths form granulomas in them with larvae inside. In them, larvae are viable for several years.
Infection pathways
The main source of infection is sick dogs. Toxocariasis is not transmitted from a sick person. Transmission is possible by contact with a sick dog, especially with a puppy with worm eggs on its coat.
The pathway of infection is fecal-oral. Up to 15 thousand eggs per 1 g of feces. The main reason is non-compliance with hygiene. Toxocar eggs are found in the ground and penetrate a person due to non-observance of personal hygiene, dirty products, etc.
It is important to note that the eggs must pass the stage of maturation in the soil within a month.
Adults get sick less often, with the exception of some professions: dog handlers, veterinarians, dog breeders, and hunters. Toxocariasis can begin to destroy organs even several years after infection.
Infection sequence
In dogs, larvae can penetrate the placenta of females into the fetus and develop there. As a result, puppies are born already infected with worms. From eggs in the intestines of humans appear larvae. They are able to penetrate through the walls of the intestine into the bloodstream and through vessels reach any organs or tissues. There they are encapsulated and retain their biological activity for a long time.
As for the feline toxocar larvae, after migration through the body they again reach the intestines in the adult stage, which leads to the imaginal form of the disease.
Infection mechanism
Infection occurs at any time of the year, but more often in the autumn-summer period. Toxocar eggs enter the oral cavity, through the stomach they reach the intestines, where larvae exit. They enter the bloodstream, and then into the liver. Some parasites in the portal vein system reach the right half of the heart and lungs. There, some part continues the journey to other organs, occupying them. They can settle in the brain, thyroid gland, kidneys, and muscles. Here they live a long time, periodically renewing their migration and provoking relapses.
Larvae damage internal organs and die at the same time, leaving inflammation, necrosis, hemorrhage. Even cured toxocariasis may occur again.
Antibody production
During migration, blood vessels are injured with the development of inflammation and necrosis. Toxocars sensitize the body and in this case play the role of antigens. Immunity responds by producing antibodies to toxocaras. This is an immunoglobulin protein. Allergic reactions develop immediate and delayed.
They appear in the form of cutaneous erythema, edema, asthma attacks. In the blood, the number of eosinophils increases, which are attracted by the resulting immune complexes to the lesion. Thus, what do antibodies to toxocaras or antibodies mean? AT is an indicator of infection with parasitic worms.
Course of the disease
The course of toxocariasis is divided into several types:
- Asymptomatic type - no complaints and clinical manifestations.
- The hidden type is cough, migraine and abdominal pain.
- Localized is divided into ophthalmic, cutaneous, visceral and neurological.
- Systemic, affecting several organs at once.
Acute toxocariasis initially manifests itself as a small fever, malaise, myalgia, swollen lymph nodes, and allergic reactions.
With latent toxocariasis, the symptoms are scanty and faded, the disease is detected only in the laboratory. Chronic pathology combines both forms. They talk about her when an acute attack occurred, then remission, then again exacerbation, etc.
Symptomatic manifestations
Allergic skin symptoms are most pronounced - it is a skin form. It is accompanied by hepatosplenomegaly, fever, bronchopneumonia with attacks of suffocation and cough, swelling of the face, and the formation of granulomas in various body systems.
The main symptoms of visceral toxocariasis:
- hepatosplenomegaly;
- fever;
- bronchopneumonia with coughing up to suffocation;
- puffiness of the face;
- the formation in various organs of specific granulomas in which the larvae are located.
It develops with a large number of larvae. Damage to the lungs can lead to asthma.
With neurological toxocariasis, the brain is affected and mental disorders occur, while:
- hyperactivity
- cramps
- decreased attention and memory;
- paresis and paralysis.
For the development of ocular toxocariasis, a small number of larvae is enough, this form lasts several years. It affects more often than adults. Only 1 eye suffers.
Larvae affect the retina and choroid, causing purulent inflammation here.
May occur:
- strabismus;
- leukorrhea;
- optic neuritis;
- keratitis;
- abscess in the vitreous body;
- decreased vision up to blindness.
Imaginal toxocariasis is rare. Manifested by nausea, abdominal pain, hypersalivation, dizziness and loss of appetite.
Complications and consequences
Effect on the basic systems of the body:
- On the part of the respiratory system - asthma, pneumonia with a fatal outcome.
- From the side of the central nervous system - cramps, paresis and paralysis.
- Eye damage leads to sepsis.
- Myocarditis.
Diagnostic measures
The diagnosis of toxocariasis is based on the clinic, an epidemiological history, and laboratory results. Detection is complicated by the fact that neither eggs nor larvae can be found in the feces. Only in intestinal form can eggs be in stool.
Since there is a sensitization of the body, after infection, class G immunoglobulins can be detected after 1.5-2 months. After 3 months, their concentration in the blood appears to be maximum, then the concentration remains stable for a long period.
The main indicator is a blood test for antibodies. An analysis of antibodies to toxocaras is a serological reaction with a toxocarias antigen. Immunoglobulin IgG has the following tasks:
- detection of a foreigner in the blood;
- the connection with the antigen and the creation of immunity against it is an antibody.
With proper preparation, 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 decryption will be as follows:
- Antibodies to toxocara norm - titer 1: 100 - does not confirm the diagnosis; a person may be a carrier.
- Caption 1: 400 - toxocaras are present in the body, but do not progress; this is characteristic of the ocular form.
- Caption 1: 600 (800) - antibodies to toxocaras have been detected, parasites are in the body, appear in acute form.
If the indicators are higher than 1: 800, then other parasites are present in the body. Then you can pass feces for analysis to detect other helminths.
To determine the presence of antibodies to toxocaras in the body, a compliment binding reaction (CSC) is also used - also a serological study.
A 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;
- decreased hemoglobin - anemia.
Biochemical analysis can reveal the following disorders:
- hyperglobulinemia;
- hyperbilirubinemia, which provokes the breakdown of red blood cells.
Additionally, you may need x-rays, ultrasound, MRI of damaged organs.
A few decades ago, a special table was developed for doctors for the significance of clinical signs and laboratory results by points.
Toxocariasis is diagnosed with a total of 12 points or more.
Possible results of ELISA
The class and number of antibodies detected determine 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 among themselves not only in the weight and structure of 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 largest molecular weight and cannot pass through the placenta.
In a 1 year old child, detection of IgM indicates the presence of infection. In 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. The analysis determines the total antibodies to toxocara IgG class. All their data are entered in a special table with the application of quantitative indicators.
Analysis preparation
A blood test for antibodies to toxocars is taken in the morning on an empty stomach from a vein. The day before the fence can not:
- drink alcohol;
- take antibacterial drugs;
- to allow physical exertion.
There are no dietary restrictions.
Decryption
What do antibodies to toxocara mean? These are indicators of the presence of parasites in the body. Helps identify the type of parasite.
A negative blood result for antibodies to toxocaras can cause ocular toxocariasis with a weak immune response or too early infection.
False positive reactions are possible in the following cases:
- gestation;
- hormonal disbalance;
- cancer, cirrhosis.
Additional studies may be prescribed.
Practice shows that not always the severity of the disease corresponds to a high level of antibodies to toxocaras. The infected are monitored, and in the event of clinical manifestations of toxocariasis, treatment is prescribed.
Treatment principles
Therapy is carried out with the help of anti-nematode drugs:
- Tiabendazole (Mintezol);
- Albendazole
- Vermox (Mebendazole);
- "Medamine."
They are effective only for larvae in free swimming. They do not act on granulomas. Their effectiveness is 50%. Therefore, repeated treatment often becomes necessary.
Preventive actions
Prevention is associated with personal hygiene, sufficient heat treatment of products, especially meat; extermination of flies - carriers of infections. A routine pet examination is also required.