Etiology and pathogenesis
The disease is caused by the larval stages of dog (Toxocara canis) and cat (Toxocara mystax) nematodes. Upon entering the human body, the larva becomes a biological dead end—it is unable to mature into an adult worm.
The main feature of the pathogenesis is the prolonged migration of larvae through the body, which lasts for several months. This leads to powerful toxic-allergic reactions and multiorgan disorders.
Epidemiology and Clinical Presentation
Infection occurs via the alimentary route through contact with soil or sand contaminated with the feces of infected animals. The disease tends to relapse and can be asymptomatic.
Two main forms are distinguished:
- Visceral form: accompanied by fever, rash, cough and bronchial obstruction, abdominal pain, hepatomegaly, as well as headaches, insomnia, and convulsions.
- Ocular form: manifests as inflammation of ocular structures and leads to decreased visual acuity.
A severe complication can be the development of bronchial asthma or unilateral blindness.
Diagnostics and treatment
The diagnosis is established based on medical history (contact with animals), specific serological tests, and general clinical blood tests revealing pronounced eosinophilia. Instrumental methods include chest radiography (searching for migrating infiltrates), pulmonary function testing (PFT), and ophthalmoscopy.
For the treatment of clinically manifest forms, etiotropic therapy with anthelmintic drugs (albendazole, mebendazole) is prescribed. Pathogenetic treatment aims to eliminate allergy and bronchospasm.
Class and exam questions
Why is man a biological dead end in toxocariasis?
The larva that enters the human body is unable to develop into an adult form, therefore the pathological process is exclusively caused by its migration.
What changes in the complete blood count are typical for toxocariasis?
Pronounced hypereosinophilia (eosinophil levels can reach up to 90%), as well as leukocytosis and accelerated ESR, are characteristic.
What are the main forms distinguished in the clinical presentation?
Clinically, two main forms are distinguished: visceral (with multiorgan involvement) and ocular (with inflammation of ocular structures and vision loss).
What else to study on this topic
- Features of the migration phase of Toxocara larvae
- Differential diagnosis of the visceral form of toxocariasis
- Instrumental diagnostic methods for ocular toxocariasis
- The role of hygiene and veterinary control in prevention
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