Parasites of freshwater fishes in North America: why so neglected?

Fish parasitology has a long tradition in North America and numerous parasitologists have contributed considerably to the current knowledge of the diversity and biology of protistan and metazoan parasites of freshwater fishes. The Journal of Parasitology has been essential in disseminating this knowledge and remains a significant contributor to our understanding of fish parasites in North America as well as more broadly at the international level. However, with a few exceptions, the importance of fish parasites has decreased during the last decades, which is reflected in the considerable decline of funding and corresponding decrease of attention paid to these parasites in Canada and the United States of America. After the 'golden age' in the second half of the 20th Century, fish parasitology in Canada and the United States went in a new direction, driven by technology and a shift in priorities. In contrast, fish parasitology in Mexico has undergone rapid development since the early 1990s, partly due to extensive international collaboration and governmental funding. A critical review of the current data on the parasites of freshwater fishes in North America has revealed considerable gaps in the knowledge of their species composition, host specificity, life cycles, evolution, phylogeography, and relationships with their fish hosts. As to the key question, "Why so neglected?" this is probably because: (1) fish parasites are not in the forefront due to their lesser economic importance; (2) there is little funding for this kind of research, especially if a practical application is not immediately apparent; and (3) of shifting interests and a shortage of key personalities to train a new generation (they switched to marine habitats or other fields). Some of the opportunities for future research are outlined, such as climate change and cryptic species diversity. A significant problem challenging future research seems to be the loss of trained and experienced fish parasitologists. This has 2 major ramifications: the loss of expertise in identifying organisms that other biologists (e.g., ecologists, molecular biologists, evolutionists) work with, and an incomplete comprehension of ecosystem structure and function in the face of climate change, emerging diseases, and loss of biodiversity.

The power of torpedo fish as a pathological model to the understanding of nervous transmission in Antiquity.

The torpedo effect was known long before electricity was discovered. How was it explained? In early accounts on the subject, Emil du Bois-Reymond found remarkable observations and hypotheses. In Antiquity, zoological interest is illustrated by Aristotle and followers, who were intrigued by torpedo's behaviour and capacity to act from a distance. Alexandrian physicists were more interested in the propagation, as for light, of its effect in matter, conceived as either corpuscular or continuous. The theory of nervous action is linked to these conceptions and separated in various hypotheses among which that on qualitative alteration. However, the medical approach of toxicology takes over this debate and brings back torpedo's property in the frame of pathology.

Octomacrum europaeum (Monogenea: Octomacridae) in Europe: historical and recent perspectives.

Several specimens of Octomacrum europaeum (Octomacridae: Monogenea) were found on the gills of Alburnoides bipunctatus in the Czech Republic. The morphometry of the specimens measured in the present study was in agreement with that of the original description.

A historical review of fish vaccinology.

The first report on fish vaccination to appear in a widely read international scientific journal was that by Duff [5] dealing with his results obtained with anti-furunculosis vaccines. Duff's report did not result in an immediate landslide of fish vaccination trials in other laboratories because, in the years following the second world war, the preoccupation was with disease control using the newly discovered antibiotics. In fish culture, the ensuing 30 to 40 years might accurately have been termed the "era of chemotherapy" because large numbers of antibiotics, sulpha drugs, and even mercury-based antimicrobial agents were routinely used. It was only in the mid to late 1970s, with an increased interest in fish farming, particularly marine fish farming, that attention was once again turned to the possibility of vaccination as a means of preventing/ controlling fish diseases and to the development of commercially available vaccines. The reasons for this turn of events were varied: the high cost of using chemotherapy, the short-term nature of the protection obtained with antibiotics, the increasing appearance of antibiotic resistant fish pathogens, and, to some extent, concerns about the environmental impacts of antibiotic use. This paper briefly outlines the success that has attended efforts to develop vaccines against some of the more important bacterial diseases of cultured fish and the progress made in developing vaccines against important viral fish pathogens. In the process, an attempt will be made to show how fish vaccine development has benefited from an improved knowledge of the fish's immune system and from a better understanding of the virulence factors possessed by particular fish pathogens.