For a number of years, people have talked about Anisakis, a parasite found in fish and passed on to the human when undercooked fish are ingested. Fresh anchovies in vinegar, a typical Spanish dish, together with the exotic Japanese dishes such as ‘sushi’ and ‘sashimi’, present a risk because they are not not cooked before being eaten. Normally, the Anisakis larvae are found in the intestine and muscles of fish, which act as hosts in the parasite’s lifecycle after eating other fish or crustaceans already infected.
The research group ‘Ichthioparasitología’ of the Department of Parasitology of the Universidad de Granada , headed by Professors Adela Valero López and Francisco Javier Adroher Auroux, has analysed the presence of living larvae of the Anasakis parasite in eight different species of fish suitable for human consumption, such as horse mackerel, blue whiting, hake, anchovy, and sardine, from the Mediterranean coasts of Andalusia as well as from other fishing grounds. Their study has revealed that the fish captured off the Andalusian coasts are less infested with Anisakis than are those from other areas such as the Atlantic, the Cantabrian or even other fishing areas in the Mediterranean. This could be related to the scarcity of marine mammals, which are natural hosts of this parasite, along the Andalusian coasts.
According to the researchers from Granada, “Seven of the eight species analysed had less than 1% of Anisakis simplex in the muscles, signifying a very low infection risk for the human”. These species are sardine, anchovy, blue whiting, brotola de roca, the brotola de fango, and the red mullet. Only hake had a higher percentage (less than 6.5%, and thus also indicating low infection risk) and, when comparison was possible, the presence of these parasites in the fish consistentlyproved lower than in fish from other areas.
Nevertheless, Valero and Adroher warn that fish should be well cooked, i.e. at a cooking temperature of >60 ºC or frozen at -20ºC for 48-72 hours before consumption, in order to kill the larvae and thereby avoid any risk of infection.
The first form of anisakiasis (infection with Anisakis) is intestinal anisakiasis, which provokes stomach disorders (e.g. pain, nausea, vomiting, sores). However, it has recently been discovered that the Anisakis plays a major role in an emerging illness that is becoming steadily more widespread: food allergy.
The teachers from the UGR are currently working in a novel research line: the possible anti-Anisakis properties of some plants in our cultural environment used in the seasoning of the fish or as an infusion, since in some areas of China the consumption of fish in combination with certain native plants used as seasoning seems to reduce human infection with this parasite.
This research group of the Universidad de Granada has publications in some of the best international journals of Parasitology such as Molecular and Biochemical Parasitology. It is the only research group in Andalusia that is working on this topic and collaborates with: Professors Rocío Benítez, Josefa Lozanos and Joaquina Martín from the Department of Parasitology (UGR);Professor Concepción Navarro from the Department de Pharmacology (UGR), for the guidance and selection of vegetable products; Professor Manuel Díaz from the Department of Applied Biology (Universidad de Almería), in the study of the protease; and Professor Simonetta Mattiucci (Institute of Parasitology of La Sapienza in Rome), in the molecular techniques for identifying the different species of the genus Anisakis.
Reference:
Prof. Adela Valero López and Francisco Javier Adroher Auroux.
Dpto. de Parasitología of the Universidad de Granada.
Telephone Numbers: 958 243 860 – 958 243 857. E-mail address: avalero@ugr.es; fadroher@ugr.es
