Histopathological changes in the organism of rats under the chronic course of experimental infection with larvae of Eustrongylides excisus (nematoda: Dioctophymatidae)

Abstract

Aim. To evaluate the pathological effect of Eustrongylides excisus nematode larvae (L3–L4) on the organism of laboratory rats, the latter were infected per os by these parasites. The larvae of Eustrongylides excisus were obtained from perch (Perca fluviatialis, Linnaeus, 1758), caught in the Dnipro-Buh estuary – 46°37’48.45” N, 31°51’43.72” E, near the village of Dniprovske, Mykolaiv region (Ukraine). Methods. The experimental studies, which lasted for 30 days, were conducted using 15 non-linear male laboratory rats, which composed the experimental group by the analogy principle, three other animals were used as control. The intensity of the pathological process under the chronic course of eustrongylidosis was evaluated by the histological testing of the damaged organs of animals under investigation, which were euthanized after the completion of the waiting period. Results. The histological testing found pathological changes in the tissues of the brain, lungs, spleen, and organs of the gastrointestinal tract. There was a notable formation of non-specific granulomas (i.e. the ones, which were not found in the control group of animals), which consisted of adipose and connective tissue of mesostenium, mesocolon, and mesogaster. These granulomas had vivid exudative-proliferative inflammation and contained the elements of parasitic larvae (remnants of larvae bodies: fragments of cephalic and caudal ends, cuticles), which were subjected to considerable destructive changes. The walls of these granulomas consisted of fibrin and necrotic detritus. It was found that the animals of the group (the waiting period of 30 days) had mostly fibrino-purulent type of inflammatory reaction with the prevailing exudative-proliferative processes and the formation of non-specific granulomas. Conclusions. The results of scientific studies demonstrated necrotic and hypoxic-ischemic changes in the brain tissues; signs of cardiovascular deficiency, dystrophic and hypertrophic changes in the myocardium tissues; purulent inflammation of pleura and interstitial tissue of the lungs; changes in kidney tissues in the form of balloon dystrophy and granular degeneration of tubular epithelium; acute exudative-proliferative inflammation of the liver capsule and parenchyma; proliferation of white pulp with necrotic changes in lymphoid follicles; the thickness of the walls of gastrointestinal organs was considerably infiltrated with eosinophils, plasma cells, and macrophages. The phenomena of tissue hypertrophy and sclerosis as a pathomorphological response of the organism to the chronic course of the disease were determined.