Synergistic effects of using sodium hypochlorite (bleach) and desiccation in surface inactivation for Toxocara spp

Abstract

Toxocara cati and T. canis are parasitic nematodes found in the intestines of cats and dogs respectively, with a cosmopolitan distribution, and the potential for anthropozoonotic transmission, resulting in human toxocariasis. Spread of Toxocara spp. is primarily through the ingestion of embryonated eggs contaminating surfaces or uncooked food, or through the ingestion of a paratenic host containing a third-stage larva. The Toxocara spp. eggshell is composed of a lipid layer providing a permeability barrier, a chitinous layer providing structural strength, and thin vitelline and uterine layers, which combined create a biologically resistant structure, making the Toxocara spp. egg very hardy, and capable of surviving for years in the natural environment. The use of sodium hypochlorite, household bleach, as a disinfectant for Toxocara spp. eggs has been reported, with results varying from ineffective to limited effectiveness depending on parameters including contact time, concentration, and temperature. Desiccation or humidity levels have also been reported to have an impact on larval development and/or survival of Toxocara spp. eggs. However, to date, after a thorough search of the literature, no relevant publications have been found that evaluated the use of sodium hypochlorite and desiccation in combination. These experiments aim to assess the effects of using a combination of desiccation and 10% bleach solution (0.6% sodium hypochlorite) on fertilized or embryonated eggs of T. cati, T. canis, and T. vitulorum. Results of these experiments highlight the synergistic effects of desiccation and bleach, and demonstrate a relatively simple method for surface inactivation, resulting in a decrease in viability or destruction of T. cati, T. canis and T. vitulorum eggs. Implications for these findings may apply to larger scale elimination of ascarid eggs from both research, veterinary, and farming facilities to mitigate transmission.

Keywords: Bleach; Control; Desiccation; Disinfection; Inactivation; Toxocara.