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We performed a systematic review and meta-analysis on observational studies to evaluate the possible associations between Toxocara species seropositivity and allergic skin disorders (ASDs). We searched the MEDLINE, ScienceDirect, Scopus, Web of Science and Google Scholar databases to 15 May 2018 to identify the relevant studies. We used a random effects meta-analysis model to generate the pooled odds ratio (OR) and 95% confidence intervals (CIs). Fifteen studies, including eight studies with a case-control design (735 patients and 1342 controls) and seven studies with a cross-sectional design (a total of 4804 participants, 1302 individuals with ASDs and 3502 without ASDs), were included in the meta-analysis. We found an increased risk for ASDs in individuals with Toxocara seropositivity (OR 1.75 [95% CI 1.16 to 2.64]). Subanalysis showed that Toxocara seropositivity was significantly associated with urticaria (OR 2.97 [95% CI 1.53 to 5.76]), however, it was not significantly associated with atopy (OR 1.08 [95% CI 0.55 to 2.15]) and eczema (OR 1.62 [95% CI 0.95 to 2.78]). Moreover, the pooled ORs were 2.34 (95% CI 1.32 to 4.15) and 1.27 (95% CI 0.69 to 2.35) for case-control and cross-sectional studies, respectively. The results of our study support hypotheses regarding the existence of a positive relationship between Toxocara infection and allergic disorders, although this association should be further investigated by longitudinal and mechanism studies.

Background: Pediatric asthma is a prevalent disease and has a significant immunologic and inflammatory nature. In recent years, the role of vitamin D3 in immunologic processes has been studied, and many aspects of this role have been clarified in some human diseases. Objective: The aim of this study was to evaluate the relationship among the vitamin D3 status, Pediatric Asthma Severity Score (PASS), and inflammatory indicators of pediatric asthma. Methods: Among all of the pediatric patients with asthma and with asthma exacerbation, 100 patients were randomly enrolled in the study and subdivided into three groups according to serum levels of 25-OH vitamin D3. The control group consisted of 100 sex- and age-matched healthy subjects. Asthma exacerbation severity was evaluated based on the PASS before starting the medical care. The count of the white blood cells, eosinophil count, and serum levels of total immunoglobulin E (IgE) plus 25-OH vitamin D3 were measured in all the subjects. The obtained data were then compared via proper statistical tests. A p value of <0.05 was considered as statistically significant. Results: The median level of serum IgE was increased in patients with vitamin D3 deficiency compared with other groups. There was a significant inverse correlation between serum levels of 25-OH vitamin D3 and IgE in pediatric patients with asthma (r = ‐0.483, p = 0.001). Furthermore, the serum levels of 25-OH vitamin D3 also significantly inversely correlated with the PASS (r = ‐0.285, p = 0.004). Conclusion: Vitamin D3 deficiency is associated with exacerbation severity and serum IgE levels in patients with pediatric asthma; hence, it can have an important role in pediatric asthma pathogenesis, possibly through IgE.

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Background: Besides the well-known risk factors, Toxocara infection is thought to play a significant etiological role in the development of childhood asthma. To further explore this association, the prevalence of Toxocara infection in sera of asthmatic children and healthy controls in northern Iran was investigated. Methods: In this case-control study, cases were 145 physician-confirmed asthmatic children diagnosed according to the Global Initiative for Asthma (GINA) guidelines. Controls were 115 age–sex–residence-matched children who did not have physician-diagnosed asthma. The presence of anti-Toxocara immunoglobulin G (IgG) was tested using enzyme-linked immunosorbent assay. Univariate and multivariate logistic regression methods were used for case-control comparisons. Results: Seropositivity rate was 4.1% (95% CI, 3.4–4.7%) in asthmatic children and 0.86% (95% CI, 0.71–1.0%) in controls, suggesting a strong association (P-value < 0.02). Moreover, Toxocara infection was not significantly more prevalent (P-value = 0.12) in children with moderate sustainable asthma (9.3%, 3/32) than in children with mild sustainable asthma (2.3%, 3/113). Mean total immunoglobulin E (IgE) level was significantly higher in Toxocara-infected children (222.3 ± 367.1) than in non-infected children (143.19 ± 218.05) in the case group (P-value < 0.05). Conclusions: Our findings indicated that Toxocara infection can play an important role in childhood asthma. Further experimental and epidemiological studies are needed to clarify this hypothesis.