Aspects of morphofunctional relationships in the “parasite–host” system in carp phylometroidosis

The patterns of development and morphofunctional relationships in carp phylometroidosis are highlighted using histomorphological analysis. The material for the research was one-year-old, one-year-old, and two-year-old carp (Cyprinus carpio L.), infested with the nematode Philometroides lusiana (Vismanis, 1966), from fish farms in the Western region. The fish were selected during the growing season. From intensively affected carp in the period from May to October, such organs as the intestine, kidneys, hepatopancreas, spleen, gills, brain, skin together with muscle tissue, and swim bladder were selected. To clarify individual aspects of the morphofunctional relationships of phylometroidosis with intermediate and final hosts in the parasite-host system, material obtained from spontaneously and experimentally infected carp, which were kept in pools and baths, was used. For microscopic studies, a Jenamed-2 microscope (Karl Zells Jenna) was used. Photography was done using a microphoto attachment MFN 11 and a digital camera. Parasitism in the skin of carp by sexually mature females of phylometroides leads to intrahelminthic adhesiveness, which is aimed at intensive nutrition of the uterus at the expense of carp tissues and other tissues of the parasite itself to ensure the nutrition of eggs and larvae at the early stages of their development. This phenomenon is accompanied by inflammatory processes in the skin and increased metabolic processes in the carp's body. Male helminths, parasitizing in the swim bladder, do not significantly affect the state of the carp body. After being released and migrating into the intestinal wall of carp, phylometroide larvae destroy the surrounding tissues due to their high level of metabolism, and these nutrients are used to ensure their movement, nutrition, growth, and development. The pathogenic effect of larvae on the host organism depends on the intensity of invasion, migration routes, and damage to organs and tissues. In the end, damage from migrating larvae is local in nature, tissues and organs generally maintain satisfactory conditions for their functioning.