Trematode-host interaction by an example of Cryptocotyle infection in fish of the Gobiidae family in estuary waters and the Black Sea in Southern Ukraine

Abstract

. This article presents the results of an analysis of the formation and functioning of the «parasite-host» system, as well as its constituent elements, on the example of goby fish (Gobiidae) and trematodes of the Heterophyidae family. The research work consisted of separate stages: determine the distribution of the causative agent of cryptocotylosis among goby fish in a natural reservoir, study clinical signs during this parasitic disease; conduct an experimental invasion of research ducklings in order to determine the pathogenic effects on the bird organism and study the morphology of the mature parasite. The main stages of cryptocotylosis pathogen life cycle were outlined. The distribution of this parasite in the Dnieper-Bug estuary water area and part of the Black Sea in the Nikolaev and Odessa regions was established. It was noted that the parasitic trematode strategy and shared co-evolution led to the appearance, during evolution, of adaptations that balance the dynamic interaction between the parasite and its host: anatomical and morphological characteristics, antigenic mimicry, physiological and trophic characteristics of the parasitic way of being, etc. We also present an analysis of the Heterophyidae families’ trematode behavioral characteristics at different stages of development: eggs, sporocysts, miracidia, cercaria, metacercaria and daydreaming – are mature individuals. Trematode’s adaptive abilities appear already in the early stages of its life cycle. According to the results of experimental invasion of research ducklings, the pathogenic effect of the cryptocotylosis causative agent on the bird organism as the definitive host was established. While determining features of the parasites pathological effect on the organism of experimental ducklings, we recorded inflammatory processes in the intestines of birds: enteritis of varying severity, secondary lesions of the hepatobiliary system. The influence of the parasite on the host organism is not limited only to changes at the organ level. Non-specific protection is manifested mainly through the development of inflammatory reactions at the cellular and humoral levels. A retrospective literature analysis on the basic principles of the “parasite-host” interaction system was also carried out.