Unusual Localization of Pennella Sp. in Swordfish (Xiphias gladius) Hearts

Abstract

The genus Pennella comprises hematophagous parasites of marine aquatic species, including cephalopods, marine mammals, and pelagic fish. Nine species have been officially included in the genus Pennella plus another six species inquirendae. They are most often found in the host’s musculature, without penetrating internal organs. For the present study, 83 hearts from swordfish (Xiphias gladius) caught in the Mediterranean Sea were sampled and immediately fixed in formalin for histopathological analysis. In total, 10 (12.05%) hearts were found to be parasitized by copepods of the genus Pennella. Macroscopically, there was mild-to-severe fibrinous pericarditis with atrial wall thickening and multiple parasitic nodules. Histologically, the parasitic nodules were surrounded by an inflammatory-necrotizing reaction. Parasitic infestation by Pennella spp. is common in pelagic fish and in swordfish, in particular. Here, however, we report atypical cardiac localization. A future area of focus is the evaluation of cardiac Pennella spp. infestation by histopathology and genetic identification of the parasites.

The Complete Mitochondrial Genome of Pennella sp. Parasitizing Thunnus albacares

“…They can infect fish of economic interest, including tuna and swordfish. They penetrate the muscles of the host, seriously damage the internal organs, and grow by absorbing the nutrients in the fish, resulting in fish stress response, loss of appetite, changes in swimming speed, and threatening important functions such as heart, intestine and stomach ( Mugetti et al., 2021 ). We can see from the previous summary that Pennella sp.…”