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Fasciola
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
According to their preferences for vertebrate host tissues, members of the subclass Digenea are divided into tissue flukes and blood flukes. Tissue flukes infect the bile ducts/liver (e.g., Clonorchis sinensis, Opisthorchis viverrini, F. hepatica, and F. gigantica), lungs (e.g., Paragonimus westermani), or other biological tissues, whereas blood flukes spend some time in the blood during their life cycle (e.g., Schistosoma mansoni, S. japonicum, S. haematobium, S. mekongi, and S. bovis) [1].
Evolutionary Biology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2015
Eric S. Loker, Bruce V. Hofkin
Over evolutionary time, many natural experiments on parasite transmission have been undertaken, and no doubt most have failed. Today we see the results of the successful experiments. We also see evidence for the evolution of innovations that have enabled some groups to become very successful. For example, there are an estimated 18,000 living digenetic trematode species as compared to only about 80 species in their sister group, the aspidogastreans. There are two essential innovations that separate these two parasite groups. In the digeneans, larval development in the snail host is accompanied by asexual reproduction and the production of thousands of progeny, each capable of going on to produce eventually an adult worm in another host (Figure 7.25). Furthermore, these asexually produced progeny, the cercariae, typically leave the molluscan host and engage in behaviors that directly favor transmission. By contrast, an aspidogastrean developing in the molluscan host does not undergo asexual reproduction and can only await predation by a vertebrate host, if the life cycle even involves one. Do not conclude, however, that the aspidogastreans are in some way inferior; they are often found in ancient lineages of hosts (see Szidat’s rule in Box 7.6) and have probably deployed their relatively simple but obviously effective life cycles for over 400 million years.
Interactive associations between fish hosts and monogeneans
Published in G. F. Wiegertjes, G. Flik, Host-Parasite Interactions, 2004
Kurt Buchmann, Thomas Lindenstrøm, Jose Bresciani
Despite the well-developed protection mechanisms present in fish a vast majority of pathogens are able to infect the host with varying success. Evidently the parasites must possess some elements of immune evasion. In fact, the estimate of a total of more than 24 000 monogenean species worldwide is an indicator of the successful evolution of the group and the powerful evasion of the anti-parasitic host armament. In fact, histopathological studies of fish tissue infected with monogeneans do often show a limited damage to parasite surfaces. Although surrounded by a dense layer of reactive cells the monogenean tegument appear intact. It has even been suggested that the parasites exploit the tissue reaction by using it for improved attachment on the host. It is especially noteworthy that the blood-feeding polyopisthocotyleans are able to resist direct intake of blood containing complement factors, immunoglobulin, lectins, leucocytes and other reactive elements and substances. This will indicate well-developed evasion mechanisms. The subject of immune evasion has especially been treated for helminth groups such as digeneans, cestodes and nematodes. The various evasion mechanisms in these groups range from protection against complement, immunoglobulins, diversion of cytokine expressions to behavioural responses.
Ecological studies on the helminth parasites of catfishes Bagrus spp. (Bagridae) and Chrysichthys auratus (Claroteidae) inhabiting Damietta branch, River Nile, Egypt
Published in Egyptian Journal of Basic and Applied Sciences, 2023
Hend E. Allam, Mohamed I. Mashaly, Mohamed M. El-Naggar
In Bagrus spp, the digeneans attained the highest prevalence, if compared with the monogenean and nematode parasite species. The present data agree with that reported by Saoud and Wannas [25]. However, Abdel-Gaber et al. [30] reported that the nematode species have the highest prevalence followed by cestodes in C. gariepinus from Lake Manzala. Mgbemena et al. [31] reported the highest prevalence of nematodes, especially Camallanus sp., followed by Capillaria sp. with a corresponding low prevalence of the cestode, Tetracampose ciliotheca from C. gariepinus in Nigeria.