Allergy Asthma Immunol Res.  2015 Sep;7(5):467-475. 10.4168/aair.2015.7.5.467.

The Prevalence of Toxocariasis and Diagnostic Value of Serologic Tests in Asymptomatic Korean Adults

• Lee JY
• Yang MH
• Hwang JH
• Kang M
• Paeng JW
• Yune S
• Lee BJ
• Choi DC

• KMID: 2147955
• DOI: http://doi.org/10.4168/aair.2015.7.5.467

Abstract

PURPOSE
Toxocariasis is the most common cause of peripheral blood eosinophilia in Korea and produces eosinophilic infiltration in various organs, including the lung. However, the prevalence of toxocariasis in the general population is rarely reported.
METHODS
We investigated the seroprevalence of Toxocara larval antibody among asymptomatic people who attended Samsung Medical Center for a health checkup, including low-dose chest computed tomography (CT) between March 2012 and December 2013. A total of 633 people (400 men and 233 women) were prospectively recruited.
RESULTS
The Toxocara-seropositive rate was 51.2% using the current cutoff value based on Toxocara enzyme-linked immunosorbent assay (ELISA) (67.0% for men and 24.0% for women). In the multivariate-adjusted model, age (odds ratio [OR], 1.08; 95% confidence intervals [CI], 1.04-1.11), male sex (OR, 3.47; 95% CI, 2.26-5.33), rural residence (OR, 1.55; 95% CI, 1.05-2.30), and history of raw liver intake (OR, 8.52; 95% CI, 3.61-20.11) were significantly associated with Toxocara seropositivity. When subjects were divided into 3 groups using cutoff values base on weak positive and strong positive control optical densities (ODs), the ORs for peripheral blood eosinophilia and serum hyperIgEaemia were 0.31 (95% CI, 0.02-2.89) in the weakpositive group and 36.64 (95% CI, 11.73-111.42) in the strong positive group compared to the seronegative group. Similarly, ORs for the solid nodule with surrounding halo were 2.54 (95% CI, 0.60-10.84) in the weak positive group and 15.08 (95 CI 4.09-55.56) in the strong positive group compared to the seronegative group.
CONCLUSIONS
The study indicated that the Toxocara-seropositive rate obtained by using the current cutoff value based on ELISA was high in the asymptomatic population in Korea. The results of this study suggest that active toxocariasis may be more frequently seen in the Toxocara-strong positive group than in the Toxocara-weak positive group.

Keyword

Toxocara canis; toxocariasis; prevalence; diagnosis

MeSH Terms

Adult*
Diagnosis
Enzyme-Linked Immunosorbent Assay
Eosinophilia
Eosinophils
Humans
Korea
Liver
Lung
Male
Prevalence*
Prospective Studies
Seroepidemiologic Studies
Serologic Tests*
Thorax
Toxocara
Toxocara canis
Toxocariasis*

Figure

• 

  Fig. 1 Proportion of Toxocara grade according to variables in the study population. (A) The proportion of Toxocara grade according to history of raw-food intake. (B) The proportion of Toxocara grade according to the amount of raw liver intake. (C) The proportion of Toxocara grade according to peripheral blood eosinophilia and serum hyperIgEaemia. Paticipants were divided into 3 groups according to Toxocara grade: those with Toxocara optical density (OD) less than a weak-positive control OD (negative group), those with Toxocara OD between weak positive and strong positive control ODs (weak positive group), and those with Toxocara OD greater than the strong-positive control OD (strong positive group).

• 

  Fig. 2 Standardized Toxocara values according to variables in the study population. (A) The median standardized Toxocara values (interquartile range) were 0.26 (0.06-0.61) in the Toxocara-seronegative group and 2.38 (1.66-2.93) in the Toxocara-seropositive group. (B) The median standardized Toxocara values were 0.36 (0.07-0.95) in participants without history of raw food intake, 0.78 (0.15-1.93) in those with history of raw meat intake, 1.96 (0.96-3.10) in those with history of raw liver intake, and 2.29 (1.33-2.88) in those with history of both raw liver and raw meat intake. (C) The median standardized Toxocara values were 0.49 (0.09-1.27) in participants with no raw liver intake, 1.64 (0.77-2.51) in those with a small amount of raw liver intake, 2.53 (1.80-2.93) in those with a moderate amount of raw liver intake, and 2.62 (1.71-3.36) in those with a large amount of raw liver intake, (D) The median standardized Toxocara values were 0.67 (0.16-1.57) in participants with normal eosinophil count and IgE level, 0.85 (0.28-2.53) in those with peripheral blood eosinophilia, 2.14 (1.36-2.86) in those with serum hyperIgEaemia, and 3.12 (2.63-3.28) in those with both peripheral blood eosinophilia and serum hyperIgEaemia.

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