This article presents an analysis of literature data on immunodeficiency in animal helminthiases. Parasites, through their immunosuppressive impact on the immunological status, can significantly aggravate processes within the immune system, promoting the development of immunodeficient states. Parasitic diseases suppress immune responses, leading to the development of secondary persistent immunodeficiency due to the inadequacy of the body's natural defense mechanisms. When infected with helminths, the human body mobilizes all its defense mechanisms; however, in some cases, when the fight against parasites is prolonged, immune reactions become inadequate, which may result in immunopathological manifestations and dysfunctions of various organs.