This study assessed the anisakid nematode distribution pattern in the fish collected from coasts of Mediterranean Sea, Egypt, during the period September 2010-April 2011. Two hundred thirty out of 300 (76.7%) Dicentrarchus labrax (European seabass) marine fishes belonging to family Moronidae were dissected and found to be infected with larva three nematodes. The larvae had been studied by light and scanning electron microscopy. The present work represents the first record of the presence of the parasite in this fish in the Mediterranean Sea. The concentrations of some heavy metals (Pb, Zn, Fe, Cd, Cu, Mn, Ni) in parasites as well as in tissues of fish were measured. The presented results showed that the nematode parasites are able to accumulate heavy metals in their tissues and in some cases that they are able to accumulate large amounts of heavy metals in a higher amount than host tissues. This demonstrated their sustainability as bioindicators of environmental pollution by removing heavy metals and help in the survival of fish.

Three juvenile nematode parasites were collected naturally from 90 (75 %) out of 120 specimens of the marine greater lizard fish Saurida undosquamis captured from water coasts at Hurghada City along the Red Sea in Egypt during the period from September 2013 to April 2014. Worms were identified on the basis of light and scanning electron microscopy. Two of the recovered worms were isolated from the peritoneal cavity of the infected fish around the wall of the stomach as encapsulated larvae. The anisakid juvenile Anisakis sp. (Type II) was characterized by an anteroventrally triangular mouth, with a boring tooth; its postanal tail was rounded, without a terminal mucron or spine. The gnathostomatid Echinocephalus overstreeti was characterized by the presence of a cephalic bulb armed with six transverse rows of spines which were slightly more compact near the anterior end of bulb with maximal separation near the midbulb; the cephalic bulb terminated at a pseudolabia which situated dorsoventrally and reached its greatest width at the posterior one third of the body, The postanal tail terminated at a pointed mucron. The third juvenile species, Hysterothylacium patagonense (Anisakidae), was isolated from the intestine of the infected fish; they are characterized by a small-sized body with a conical tail provided by a nodulose apex, and the anterior end was equipped with three lips. A dorsal lip slightly smaller than the two subventrals left a deep postlabial groove and prominent lateral flanges in between, and the proximal part of each lip was smooth. The three described species were compared morphologically and morphometrically with some of the previously recorded species of the same genus. From this comparison, the similarity and variations between these species were described and concluded that the present study should be considered as a new host record in Egypt.

In the present study, the morphology and morphometric characterization of Dujardinnascaris mujibii (Heterocheilidae) and Hysterothylacium aduncum (Anisakidae), new nematode parasites infecting the sea bream Pagrus pagrus (Osteichthyes, Sparidae), were described for the first time from the Gulf of Suez and Hurghada City of the Red Sea, Egypt. Ninety-eight (70 %) and 62 (44.2 %) out of 140 of the examined fish were naturally infected with these nematodes, respectively. The infection was investigated macroscopically by the occurrence of these parasites in the flesh, stomach, intestines, as well as their body cavities as adult and larval stages. D. mujibii is characterized by an elongated body with a length of 36.4 ± 3 (23-38) mm (female) and 20 ± 3.0 (17-24) mm (males); the head is provided with three prominent lips each with four teeth like structures and the apical lip is embossed with a regular zigzag pattern as revealed by SEM. Interlabia were present, with prominent grooves. Juvenile stage is smaller than adults and provided with a spiny mucron. H. aduncum was small, measured 22.5 ± 2.0 (20.0-24.3) mm in length (female) and 16.3 ± 2.0 (14.5-17.4) mm (male). The head region bears three large lips which were clearly separated from each other, with the apical one having two rounded ends and the space between the two adjacent lips occupied by very prominent interlabia. The present study represents new host and locality records from P. pagrus fish in Egypt.

Four previously unrecognized trypanorhynchids are described based on fish specimens from Sparidae and Mullidae host fish of the Red Sea. From September 2010 to June 2011, 66 specimens of the sea bream Pagrus pagrus (F: Sparidae) and 43 of the red mullet Mullus barbatus (F: Mullidae) were purchased from markets in the Suez and Hurghada cities of the Red Sea. The fishes were measured, and their organs investigated for helminth infections. Forty-one (37.6 %) out of the 109 fish specimens investigated were parasitized with Trypanorhyncha metacestodes, identified as Callitetrarhynchus speciouses Linton 1897, Pseudogrillotia sp. Dollfus 1969, Kotorella pronosoma Stossich 1901 from P. pagrus, and Nybelinia bisulcata Linton 1889 from M. barbatus in the mesentery and peritoneal cavity, with prevalences of 16.5, 11.0, 6.0, and 12.0 %. All of these larval stages were encapsulated larvae in blastocysts. C. speciouses is characterized by an elongated scolex, two bothria, a long postbulbosa, and four elongated bulbs. Pseudogrillotia sp. possesses a scolex with two lateral patelliform bothridia; posterior margins are free, not notched. A long sheath was observed, which was irregularly coiled when tentacles invaginated. N. bisulcata possesses an acraspedote scolex with four bothridia, which are broad, bean-shaped. The tentacles are spirally coiled, supplied with hooks with abruptly turned points. The four tentacles sheaths rose from scolex as two anterior (front) and two posterior (back) which overlap at the apices of bulbs. K. pronosoma is characterized by a short body with a craspedote scolex and four bothridia. The tentacles are short and emerge pairwise. The presence of Trypanorhyncha metacestodes in the muscles does not represent a risk of infection for humans. They have a negative effect on fish esthetics. The repugnant aspect and the prohibition for commercial use by sanitary inspectors, however, cause consumer rejection. Parasites of the order Trypanorhyncha have been recorded in these host fishes for the first time.

Anisakidosis is a foodborne zoonotic infection induced by members of the family Anisakidae via the consumption of raw or undercooked fish such as sushi and sashimi. Identifying anisakid larval species is critical for the epidemiology and diagnosis of diseases caused by them. This study aimed at identifying Anisakis larvae collected from marine fish in Egyptian waters based on morphological characteristics and molecular analysis. Thirty marine fish bar-cheeked trout, Plectropomus maculatus, were collected from Hurghada, Red Sea, Egypt, to investigate larval nematodes of the genus Anisakis. The larvae were detected encapsulated in the peritoneal cavity and muscle of the fish host. This examination revealed that anisakid larvae naturally infected 19 fish specimens with a prevalence of 63.33% and a mean intensity of 4.1 ± 0.40. Most of them (68 larvae: 71.57%) were found in the musculature. Morphological and morphometric analyses using light and scanning electron microscopy revealed a head region with a prominent boring tooth, inconspicuous lips, and a characteristic protruded cylindrical mucron. All larvae in this study possessed the same morphology as Anisakis Larval type I. Molecular analysis based on ITS region using maximum likelihood and Bayesian phylogenetic methods confirmed them as Anisakis typica. This is the first study to identify A. typica larvae from the commercial fish bar-cheeked trout P. maculatus in Egyptian waters using morphological and molecular methods.