Korean J Ophthalmol.  2016 Aug;30(4):258-264. 10.3341/kjo.2016.30.4.258.

Diagnostic Value of the Serum Anti-Toxocara IgG Titer for Ocular Toxocariasis in Patients with Uveitis at a Tertiary Hospital in Korea

• Bae KW
• Ahn SJ
• Park KH
• Woo SJ

• KMID: 2373985
• DOI: http://doi.org/10.3341/kjo.2016.30.4.258

Abstract

PURPOSE
This study evaluated the prevalence of ocular toxocariasis (OT) in patients with uveitis of unknown etiology who visited a tertiary hospital in South Korea and assessed the success of serum anti-Toxocara immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) as a diagnostic test for OT.
METHODS
The records of consecutive patients with intraocular inflammation of unknown etiology were reviewed. All participants underwent clinical and laboratory investigations, including ELISA for serum anti-Toxocara IgG. OT was diagnosed based on typical clinical findings. Clinical characteristics, seropositivity, and IgG titers were compared between patients diagnosed with OT and non-OT uveitis. The seropositivity and the diagnostic value of anti-Toxocara IgG was investigated among patients with different types of uveitis.
RESULTS
Of 238 patients with uveitis of unknown etiology, 71 (29.8%) were diagnosed with OT, and 80 (33.6%) had positive ELISA results for serum anti-Toxocara IgG. The sensitivity and specificity of the ELISA test were 91.5% (65 / 71) and 91.0% (152 / 167), respectively. The positive predictive value of the serum anti-Toxocara IgG assay was 81.3%. Among patients with anterior, intermediate, posterior, and panuveitis, the prevalence rates of OT were 8.3%, 47.1%, 44.8%, and 7.1%, respectively; the seropositivity percentages were 18.1%, 47.1%, 43.7%, and 17.9%; and the positive predictive values were 38.5%, 95.8%, 92.1%, and 40.0%. The serum anti-Toxocara IgG titer also significantly decreased following albendazole treatment.
CONCLUSIONS
OT is a common cause of intraocular inflammation in the tertiary hospital setting. Considering that OT is more prevalent in intermediate and posterior uveitis, and that the positive predictive value of the anti-Toxocara IgG assay is high, a routine test for anti-Toxocara IgG might be necessary for Korean patients with intermediate and posterior uveitis.

Keyword

Enzyme-linked immunosorbent assay; Toxocariasis; Uveitis

MeSH Terms

Adolescent
Adult
Aged
Aged, 80 and over
Animals
Antibodies, Anti-Idiotypic/*blood
Aqueous Humor/parasitology
Child
Enzyme-Linked Immunosorbent Assay
Eye Infections, Parasitic/*diagnosis/epidemiology/parasitology
Female
Follow-Up Studies
Humans
Immunoglobulin G/blood/*immunology
Incidence
Male
Middle Aged
Republic of Korea/epidemiology
Retrospective Studies
*Tertiary Care Centers
Toxocara canis/*immunology/isolation & purification
Toxocariasis
Uveitis/*diagnosis/epidemiology/parasitology
Young Adult
Antibodies, Anti-Idiotypic
Immunoglobulin G

Figure

• 

  Fig. 1 Serum anti-Toxocara IgG titers in OT and non-OT uveitis patients. Patients with ocular toxocariasis (OT) had higher serum anti-Toxocara immunoglobulin G titer results than non-OT uveitis patients (0.361 ± 0.106 vs. 0.096 ± 0.098, p < 0.001). Six patients who were clinically diagnosed with OT had relatively high anti-Toxocara immunoglobulin G titer results but did not exceed the cut-off value (0.250).

• 

  Fig. 2 Patients were divided into four subgroups according to anatomic types of uveitis: anterior, intermediate, posterior, or panuveitis. The prevalence of ocular toxocariasis was 8.3% (6 / 72), 47.1% (24 / 51), 44.8% (39 / 87), and 7.1% (2 / 28), respectively, for anterior, intermediate, posterior, or panuveitis (A). The seropositivity was 18.1% (13 / 72), 47.1% (24 / 51), 43.7% (38 / 87), and 17.9% (5 / 28), respectively (B). The prevalence of ocular toxocariasis and enzyme-linked immunosorbent assay results for serum anti-Toxocara immunoglobulin G were significantly different between subgroups (p < 0.001). The p-values were obtained using the chi-square test.

• 

  Fig. 3 The change of titer for serum anti-Toxocara immunoglobulin G before and after albendazole treatment (n = 30). ELISA = enzyme-linked immunosorbent assay.

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