Toxocarosis is a parasitic disease transmitted to humans only through animals, the causative agent of which is the larva of roundworms of the genus Toxocara canis. It is generally accepted that the disease is transmitted only through infected dogs, and there is debate about the involvement of cats.

A person becomes ill in the following way:

• a sick animal excretes parasite eggs into the environment together with feces.
• due to non-compliance with the rules of personal hygiene, a person swallows particles of contaminated soil (for example, when eating unwashed fruits).
• next, the eggs attach to the small intestine, from where the larvae hatch.
• the larvae penetrate through the intestinal wall into the bloodstream and enter the liver with the blood flow, from there into the heart and then spread throughout the body.

The clinical picture of the disease depends on the organ in which the toxocara larva is "stuck". In the human body, mature individuals do not form from toxocara larvae and parasites cannot reproduce. Therefore, the disease is not transmitted from person to person.

Toxocarosis is widespread due to the biological characteristics of the pathogen. A sexually mature individual lives 4-6 months. It lays about 200 thousand eggs daily. According to analysis, out of 42,000 dogs examined worldwide, 15.2% were infected with toxocarosis. Toxocara larvae are found in soil samples in 1-60% of cases, depending on the climatic conditions of the environment (the colder it is, the less contamination). For example, in Moscow, 8.5% of soil samples were contaminated. In the USA (Markell and Vogue's Medical Parasitology, 2006), 5% of children suffer from toxocariasis or 14% of the total population (Centers for Disease Control and Prevention, Division of Parasitic Diseases, 2009). In Russia in 1999, 184,000 cases of toxocariasis were detected in children under 14 years of age and 366,000 over 14 years of age.

Risk groups include: Children; Workers in contact with land and animals; Owners of vegetable gardens, pets, in particular dogs; hunters; Persons who do not always have the opportunity to observe hygiene rules due to the peculiarities of living, working conditions, habits. The symptoms of toxocariasis are highly specific, depending on the amount and localization of the pathogen.

Acute course: Pulmonary syndrome (from cough to suffocation), t= 37-39 S, abdominal pain, headache and muscle pain, abdominal pain, myocarditis, pancreatitis, seizures, skin rashes (by type of hives).

Chronic course: manifestations fade, there is a tendency to allergies. The most serious complication: the connection with bronchial asthma. “In all patients with toxocarosis, nonspecific bronchial hyperreactivity to methacholine was detected, while only patients with toxocarosis with pulmonary syndrome have clinically pronounced and instrumentally confirmed bronchial obstruction.” (Zolotova I.A.; Dissertation “Bronchial asthma and toxocarosis, M., 2003)

Special attention is paid to ocular toxocarosis, which has the following forms (according to Chernenko, 1985): granulomas in the posterior eye; peripheral granulomas; uveitis; pars planitis; chronic endophthalmitis; abscess in the vitreous body; optic neuritis; keratitis; migrating larvae in the vitreous body.

A special feature of the diagnosis is that the standard method of feces microscopy cannot detect larvae or eggs, since the parasite does not reproduce in the human body! The most optimal is ELISA, a method for diagnosing toxocariasis, which detects IgG class antibodies to Toxocara canis larvae. Antibodies are components of the body's immune system that are produced to destroy a particular foreign protein-antigen. In this case, the antigen is a toxocara larva. There are several types of antibodies: IgA, IgD, IgE, IgG and IgM. However, the immune system cannot cope with the parasite even with a very high concentration of antibodies. Each of these antibodies has its own function and its own period of occurrence. IgG is produced 15-20 days after infection and remains in the blood for a long time. Consequently, the detection of such IgG in the blood indicates a chronic course of toxocarosis.

Read also: "TOXOCARIASIS IS EASY TO GET INFECTED, HARD TO SUSPECT..."