Effect of Irradiated Toxocara Canis Embryonated Eggs: A Promising Vaccination Strategy

Toxocariasis is a global zoonotic parasitic disease caused by Toxocara canis that poses significant public health challenges. The development of a vaccine would provide a promising method to control toxocariasis. This study aimed to evaluate the protective efficacy of gamma- and UV-irradiated embryonated T. canis eggs in mice. Seventy Swiss albino mice were classified into four groups: Group (I) the normal control; Group (II) was subdivided into a positive control once (IIA) and positive control twice (IIB); Group (III) was subdivided into a gamma-vaccinated control (IIIA) and gamma-vaccinated challenged (IIIB); and Group (IV) was subdivided into a UV-vaccinated control (IVA) and UV-vaccinated challenged (IVB). On the 28th day post-infection (dpi), scanning electron microscopy, parasitological, histopathological, immunohistochemical and biochemical analyses were performed. Larval counts in the brains and livers of vaccinated mice were significantly decreased. Compared to the positive control groups, vaccinated groups exhibited fewer histopathological alterations, a reduced immunohistochemical expression of IL-1β in the brain and CD68 in the liver, and lower IL-4, IL-10 and IgE levels in both the gamma- and UV-vaccinated challenged groups. Among the two approaches, the UV-irradiated vaccine demonstrated superior protective effects. These findings suggest that vaccination with irradiated T. canis eggs, particularly with UV treatment, is a safe, efficient and cost-effective method for immunoprophylaxis against human toxocariasis.