Specific IgG antibodies against Toxocara are used to determine exposure to Toxocara canis.
Toxocariasis is an infection caused by the ingestion of Toxocara canis dog larvae or, more rarely, the Toxocara cati cat parasite. Park grounds are usually contaminated with Toxocara canis eggs and the parasite can cause human disease by affecting the liver, heart, lung, muscles, eyes and brain.
There are generally 3 recognized Toxocara infection syndromes:
In children, asymptomatic toxocariasis is a mild, subclinical, febrile illness. Symptoms can include coughing, difficulty sleeping, abdominal pain, headaches and behavior problems. Clinical examination may reveal hepatomegaly, lymphadenitis or even respiratory wheezing.
The visceral larva migrans are caused by the migration of the larvae through the human internal organs and the resulting inflammatory reaction. A variety of symptoms can occur, such as fatigue, anorexia, weight loss, pneumonia, fever, cough, bronchospasm, abdominal pain, headaches, rashes and occasionally, seizures. Clinical examination may reveal hepatomegaly, lymphadenitis or even respiratory wheezing. Occasionally, pleural effusions are developed. Severe cases can lead to myocarditis or respiratory failure.
Ocular larva migrans, caused by the migration of the larva to the posterior part of the eye, tends to occur in older children and young adults. Patients may have impaired vision, redness of the eye or leukocoria (white pupil appearance). In the retina, granulomas and choroidal retinitis are observed, especially in the macula. The disease can result in vision loss, retinal fibrosis, retinoblastoma appearance, and retinal detachment.
In developed countries, the disease can affect up to 5% of the population while in some tropical countries the prevalence of the disease exceeds 40%.
Diagnosis of toxocariasis is difficult because confirmation of infection requires larval biopsy. Thus, the use of serological tests for the presence of Toxocara antibodies is the easiest way to detect the infection. Eosinophilia may occur, most often in patients with visceral migratory larvae. Fertilizer parasitics for ova and pests are not used since parasite eggs are only excreted by animals and not by humans .
Currently, antibody screening is the only way to confirm the clinical diagnosis. The best serological test for Toxocara is ELISA, without however, being able to distinguish between current and past parasitic infection.
See also: Toxocara canis, IgG Confirmatory Antibodies
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
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