Toxocara seropositivity in patients with atopic dermatitis and chronic urticaria: Evidence from a matched...

Toxocariasis, a globally distributed zoonotic helminth infection, has been increasingly considered a potential contributor to allergic skin diseases, though findings remain inconsistent. This case-control study assessed the association between Toxocara seropositivity and atopic dermatitis (AD) or chronic urticaria (CU) in southeastern Iran. A total of 102 individuals were enrolled, comprising 51 clinically confirmed patients and 51 age- and sex-matched controls. Anti-Toxocara IgG antibodies were detected in 19.6% of patients with allergic skin disorders, while all controls were seronegative, indicating a significant association between Toxocara exposure and allergic dermatologic conditions (p < 0.001). Univariate analyses showed significant relationships between seropositivity and residential status and type of animal contact. Participants who kept both mammals and birds had 4.81-fold higher odds of infection (95% CI: 1.04-22.26), indicating the potential contribution of multiple sources of animal contact. Also, participants residing in rural areas exhibited significantly higher chance of seropositivity compared with those living in urban settings (OR= 4.44, 95% CI 1.09-18.07). Peripheral eosinophil counts showed no association with seropositivity, lesion characteristics, or clinical presentation. Overall, these findings support a meaningful association between Toxocara exposure and chronic allergic skin disorders and highlight the importance of considering toxocariasis in the differential diagnosis of persistent atopic dermatitis or chronic urticaria in endemic regions. Further longitudinal epidemiological studies are needed to clarify exposure routes and potential causal mechanisms.