First record of Gnathostoma sp. (Owen, 1836) (Nematoda: Gnathostomatidae) infecting the European Eel Anguilla anguilla (Anguillidae) from the Mediterranean Sea, Egypt

Gnathostomiasis is a fish-borne zoonotic infection caused by eating infected seafood or fish parasitized by third-stage nematode larvae of the genus Gnathostoma. Twenty-seven fish specimens of the European eel Anguilla anguilla (Anguillidae) were collected from water coasts of the Mediterranean Sea in Egypt. Of the 27 fish that were studied, 14 fish (51.58%) were parasitized with third-stage larvae (L3) of Gnathostoma sp. (Gnathostomatidae), these larvae were investigated as encapsulated on the surface of different visceral organs and some embedded in muscles of the infected fish. By using both light and scanning electron microscopes, the morphological examination of the recovered nematodes revealed that the main diagnostic features represented by an elongated body, measured 6.5±2 (7.8–9) mm long, and its greatest width observed at the posterior one-third of the body was 0.4±0.02 (0.38–0.44) mm with narrow lateral alae, the presence of a cephalic bulb measured 0.26±0.02 (0.18–0.28) mm long, 0.31±0.02 (0.28–0.34) wide and armed with six transverse rows of spines, mouth opening surrounded by two simple lateral lips, and conical tail terminated with a pointed mucron. The described species was morphologically and morphometrically compared with some of the previously recorded species of the same genus. Based on our detailed description, the present species was identified as Gnathostoma sp. recovered from A.anguilla as the first record in Egypt.