The polyopisthocotylean Sparicotyle chrysophrii (Van Beneden et Hesse, 1863) was experimentally transmitted to gilthead seabream (Sparus aurata L.) by exposure to eggs (EGT) and by cohabitation with naturally parasitized fish (CT). In EGT trials, the infection was successfully transmitted by introducing containers with monogenean eggs in the fish tanks, with the highest infection level (85.7% prevalence, 3.3 mean intensity) achieved at 6 weeks post exposure (p.e.) to the infection dose of 650 eggs per tank. In CT trials, the progression of the infection was faster and reached higher levels than in EGT. When using small fish juveniles (30 g) (CT-2), infection reached 100% prevalence (mean intensity 8 monogeneans/fish) at 5 weeks p.e., but no eggs could be found in the fish even 10 weeks p.e. By contrast, when larger juveniles (150 g) were used (CT-1), infection levels were lower, but mature adults with eggs were detected starting from 8 weeks p.e. The effect of the parasite on the condition factor, haematocrit, haemoglobin concentration (Hb), red blood cell counts, mean corpuscular haemoglobin concentration (MCHC), mean corpuscular haemoglobin content (MCH) and mean cellular volume (MCV) of infected fish was studied in CT trials. The infection produced hypochromic anaemia, since Hb concentration significantly decreased at 5 and 10 weeks p.e. in CT-2 and at 8 weeks p.e. in CT-1. MCHC was significantly lower in parasitized than in control fish at 5 and 8 weeks p.e. in CT-2 and CT-1, respectively. Also in CT-1, MCH was lower and circulating immature erythrocytes, granulocytes and plasma cells were higher in infected fish than in control ones at 8 weeks p.e. The histopathological effects of the monogenean on the gills of naturally infected fish consisted of lamellar shortening, clubbing and synechiae. The proliferation of the epithelial tissue produced fusion of secondary lamellae, and abundant chloride cells were observed.

Instituto de Acuicultura de Torre de la Sal CSIC Torre de la Sal s n 12595 Ribera de Cabanes Castellón Spain

References provided by Crossref.org

An inside out journey: biogenesis, ultrastructure and proteomic characterisation of the ectoparasitic flatworm Sparicotyle chrysophrii extracellular vesicles

In Vitro Testing of Alternative Synthetic and Natural Antiparasitic Compounds against the Monogenean Sparicotyle chrysophrii

Are fish immune systems really affected by parasites? An immunoecological study of common carp (Cyprinus carpio)