In vitro tests of effect of disinfectants on the viability of Heterakis gallinarum nematode eggs during embryogenesis

Affecting the transmission of an infection, objects of the external environment become contaminated with pathogens as a result of their massive release by the definitive host during exogenous stages of parasites’ development, which is an important chain of their epizootic process. Therefore, disinfestation plays an important role in the complex of measures for the prevention and control of poultry helminthiases, including Heterakis gallinarum infection of chickens. The purpose of the research was to investigate in laboratory conditions the ovicidal efficiency of modern disinfectants in relation to the viability of developing eggs of H. gallinarum isolated from infested chickens. "Hermecid-VS" (didecyldimethylammonium chloride, glutaraldehyde, benzalkonium chloride) and "Arquadez-plus" (dimethyldialkylammonium chloride, didecyldimethylammonium chloride, tetrasodium salt) disinfectants were tested. These preparations had a high level of ovicidal efficiency against the eggs of Heterakis, "Hermecid-VS" in 0.25% and 0.5% concentration for exposures of 10–60 min (93.5–100.0%), "Arquadez-plus" in 1.0% concentration for exposure of 60 min (93.1%), and at 1.5% (96.8–100.0%) and 2.0% (100.0%) concentrations regardless of exposure. The ovicidal effect of disinfectants was characterized by morphological changes in the nematode eggs when using "Hermecid-VS" – accumulation of air bubbles under the shell, thinning and deformation of the shell, death and gradual resorption of the embryo, loosened egg shell and terminated embryonic development, deformation and thinning of egg the shell, and death of the embryo at the stage of formation of the larva; under the effect of "Arquadez-plus", a stop in development at the stage of cleaving blastomeres, destruction of the shell, death and evacuation of the embryo from the egg, shrinkage and gradual defragmentation of the embryo, death of the larva and its defragmentation. Under the action of disinfectants, the metric parameters of Heterakis eggs also changed. Under the influence of "Hermecid-VS" at all concentrations, the length of the eggs and the thickness of the shell were larger (by 2.9–5.4% and 26.7–46.7%), and their width was smaller (by 5.5–6.9%). With the effect of "Arquadez-plus", the length of the eggs was greater (by 0.4–2.0%), and the width was smaller (by 0.7–4.9%) only when using 0.1–2.0% concentrations of the agent. Heterakis egg shell thickness increased under the influence of "Arquadez-plus" in concentrations of 0.25–2.0% (by 33.3–40.0%). The conducted studies allow us to recommend "Hermecid-VS" and "Arquadez-plus" disinfectants in specified concentrations and modes of their use for maintaining epizootic well-being in the complex of measures against Heterakis infection of chickesn.