Epidemiology and molecular identification of Anisakis pegreffii (Nematoda: Anisakidae) in the horse mackerel Trachurus trachurus from northern Morocco.

Anisakis infection parameters were studied in horse mackerel (Trachurus trachurus) taken from two areas of northern Morocco (Tetouan and Tangier), which showed a mean prevalence of 54.9%. Identification of the ITS1-5.8S-ITS2 fragment by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) showed A. pegreffii to be the dominant species; no A. simplex s.s. were detected. The presence of A. pegreffii in horse mackerel was not influenced by the sex (P = 0.46) or catch area (Atlantic versus Mediterranean, P = 0.52) of the fish, but was significantly related to their length, weight, liver weight and gonad weight, and to the season of their capture (P < 0.05). A low prevalence (8.6%) and mean intensity (1.0) was detected in the muscle, probably related to the reduced ability of A. pegreffii to penetrate muscle. The risk of the presence of A. pegreffii in the muscle was fivefold higher in fish caught during the summer than during any other season. Susceptible members of the human population can minimize the risk of infection by avoiding the consumption of larger horse mackerel specimens during the summer.