LAUSR

Fishes commonly harbor many parasites [1,2], some of them can be transmitted to humans, leading to various diseases such as diphyllobothriosis, anisakidosis, larva migrans syndrome due to Gnathostoma spp. or Spirometra spp., liver or intestinal flukes infections and others [3]. However, only diphyllobothriosis and anisakidosis are endemic in Western countries. Anisakid nematodes, which are the most widely distributed [4], are well-known from fishermen as they can be easily seen with the naked eye in the intestines or the peritoneal cavity of freshly caught infected fish. The narrow larvae of this roundworm measure about 2 cm long and are often present by dozens. Additionally, human anisakidosis does not go unnoticed, since it induces acute stomach pain within a few hours after ingestion of raw fish. Evisceration of fishes rapidly after fishing avoid migration of the larvae in the muscles of the dead fish [5]. However, in some conditions larvae can migrate before capture of the fish [6]. For this reason, freezing fishes destined to be consumed raw is the most suitable prevention measure. By contrast, infection of fish with diphyllobothriid is more difficult to notice. First, the plerocercoid larvae of the cestode parasites are usually located in the muscle tissue of the fish, thus early eviscerating cannot get rid of it. Secondly, human infection is asymptomatic during weeks after consumption of the infected meal. It can remain so, or sometimes results in mild and non-specific gastrointestinal symptoms (diffuse abdominal discomfort, diarrhea or constipation) [7]. Thus, except when proglottids are released with feces, the disease is rarely suspected. Rare complications, e.g. intestinal obstruction or erratic migration [8], can occur, mainly in cases of massive infestation (the historically described megaloblastic anemia due to the capture of vitamin B12 by the parasite is practically exceptional nowadays and was more likely due to hostile life conditions in Europe after the war). These parasites are broad tapeworms, which have a complex life cycle with various definitive hosts over the world (various marine or terrestrialmammals, birds and even reptiles), depending on the genus and species [9]. Overall 16 species from three genera (Adenocephalus, Diphyllobothrium, and Dibothriocephalus), have been recorded from humans [9–12], but only six species are commonly diagnosed in humans, namely Adenocephalus pacificus, Diphyllobothrium balaenopterae, Dibothriocephalus dendriticus, Dibothriocephalus latus, Dibothriocephalus nihonkaiensis (previously named Diphyllobothrium pacificum, Diplogonoporus balaenopterae, Diphyllobothrium dendriticum, Diphyllobothrium latum and Diphyllobothrium nihonkaiense, respectively) and Diphyllobothrium stemmacephalum [9]. The recent taxonomic change which has occurred in 2017, consecutive to the work of Waeschenbach et al. allowed to differentiate species with marine definitive hosts (Diphyllobothrium genus) from species with terrestrial definitive hosts (Dibothriocephalus genus) [9]. Although diphyllobothrioses are zoonoses, D. latus and D. nihonkaiensis to a lesser degree, infect mainly humans as definitive hosts [9].