Occurrence and intensity of hepatic capillariasis in the barbel (Barbus rebeli) from the river Crn Drim in the Republic of Macedonia

Abstract

Capillariasis is one of the many parasites which can infect different fish tissues including the liver. The aim of our study is to demonstrate incidence of hepatic capillariasis in the population of barbel (Barbus rebeli) from the river Crni Drim, histopathological features of the liver of infected barbels, as well as associations of the infection with macrophage cells, involved in the non-specific immune response in fish. We use stereological methods to document the percentage of liver that is occupied by parasitic eggs and macrophages. Capillariid eggs were found in the liver of 68% of examined barbells. Investigations of histological slides showed that the intensity of infection varies, from one to 150 eggs per slide of liver tissue. They occupied 0.01% to 24.3% of the liver parenchyma volume. Necrosis, lymphocyte infiltration and fibrosis were weakly associated with capillariasis infection. Pigmented macrophages were found often in association with the parasite eggs. Significant positive correlation was found between the presence of capillariasis eggs and the macrophage amount. Such findings were not recorded for any fish species infected with capillariasis according to our knowledge. Moreover results of parasitic infections in barbel fish in the river Crn Drim can serve to warn fishermen and local citizens of potential risk to their health.