How to Diagnose Toxocariasis

Toxocariasis is a parasitic infection by roundworms of the genus Toxocara, specifically the dog roundworm (Toxocara canis) and cat roundworm (Toxocara cati). Cats and dogs are the primary host and humans are accidental hosts. Humans ingest the eggs which release the larvae once in the intestines. The larvae penetrate the intestine wall and move throughout the body. The following steps will show how to diagnose toxocariasis.

Instructions

• 1

  Observe the symptoms of acute toxocariasis. This most often includes abdominal pain and decreased appetite. Examine the patient for signs of extra-intestinal involvement. The liver may be swollen if it is infected, and pulmonary involvement can cause wheezing. Ocular infection can impair vision.

• 2

  Obtain the patient history. Determine if the patient has poor hygiene practices, pets in the home or a history of seizures. Children should be asked about playing in a sandbox and if they have eaten nonfood items such as dirt.

• 3

  Conduct laboratory studies when toxocariasis is suspected. The most important finding is peripheral eosinophilia, although this may absent in cases of ocular toxocariasis. The Immunoglobulin E (IgE) level may also be significantly increased.

• 4

  Make the diagnosis with serologic testing. An enzyme-linked immunosorbent assay (ELISA) can show an increase in the level of Toxocara excretory-secretory antigen (TES-Ag). A high IgG level can confirm a low-grade infection. An immunoblot can be more specific than an ELISA if bands 24, 28, 30 and 35 kD are considered.

• 5

  Use imaging studies to determine the extent of the infection. Lesions in the liver appear as small multiple hypoechoic areas with Ultrasound and areas of low density with a Computed Tomography (CT) scan.