Parasites (Monogenea) of tilapias Oreochromis niloticus and Coptodon rendalli (Cichlidae) in a river spring in Brazil.

In the present study, we examined 30 individuals of introduced African cichlids, Oreochromis niloticus and Coptodon rendalli, collected in a river spring of the Pardo River, Paranapanema River basin, southeastern Brazil. Based on morphological and molecular analyses of the partial LSU rDNA gene, we identified four species of monogeneans, Cichlidogyrus tilapiae, C. thurstonae, C. mbirizei, and Scutogyrus longicornis on the gills of O. niloticus, whereas individuals of C. rendalli were infested only with C. papernastrema. This is the first record of C. mbirizei and C. papernastrema in tilapias from Brazil. The ecological consequences of the introduction of exotic species of tilapia such as O. niloticus and C. rendalli along with their monogenean parasites in a wild environment represented by a river spring are discussed. Our new molecular data on Cichlidogyrus and Scutogyrus contribute to the investigation of the phylogenetic interrelationships of these widely distributed genera of monogeneans since their species composition is still unsettled.

Title: Parasites (Monogenea) des tilapias Oreochromis niloticus et Coptodon rendalli (Cichlidae) dans une source au Brésil. Abstract: Dans la présente étude, nous avons examiné 30 individus de cichlidés africains introduits, Oreochromis niloticus et Coptodon rendalli, collectés dans une source fluviale du fleuve Pardo, bassin du fleuve Paranapanema, dans le sud-est du Brésil. Sur la base d'analyses morphologiques et moléculaires du gène partiel de l'ADNr LSU, nous avons identifié quatre espèces de monogènes, Cichlidogyrus tilapiae, C. thurstonae, C. mbirizei et Scutogyrus longicornis sur les branchies d'O. niloticus, alors que les individus de C. rendalli étaient infestés uniquement par C. papernastrema. Il s'agit du premier signalement de C. mbirizei et C. papernastrema chez des tilapias du Brésil. Les conséquences écologiques de l'introduction d'espèces exotiques de tilapia telles que O. niloticus et C. rendalli ainsi que leurs monogènes parasites dans un environnement sauvage représenté par une source fluviale sont discutées. Nos nouvelles données moléculaires sur Cichlidogyrus et Scutogyrus contribuent à l'étude des interrelations phylogénétiques de ces genres de monogènes largement distribués puisque leur composition spécifique est encore incertaine.

Immunological and molecular evaluation of zoonotic metacercarial infection in freshwater fish: A cross-sectional analysis.

Improperly cooked fish, carrying active metacercariae (MCs), can pose a significant risk for transmitting fish-borne zoonotic trematodes (FBZTs) to human consumers. This study aimed to enhance our understanding of FBZTs by conducting a comprehensive cross-sectional analysis involving various fish species, such as Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus), and red-belly tilapia (Tilapia zillii). These fish specimens were collected from distinct Egyptian governorates, specifically Giza, Kafr al-Shaykh, and Fayoum. The recovered flukes from experimentally infected domestic pigeons were identified as Prohemistomum vivax, Haplorchis pumilio, and Pygidiopsis genata based on morphological features. Furthermore, the identity of the retrieved adult flukes was confirmed using three species-specific primers for PCR amplification and sequencing analysis of the ITS rDNA region and have been deposited in GenBank with the following accession numbers: P. vivax (OR291421.1 and OR291422.1), P. genata (OP099561.1), and H. pumilio (OM439581.1-OP090510.1). Quantitative real-time PCR targeting the immunological genes Tumor Necrosis Factor-alpha (TNF-alpha) and Interleukin-1 (IL-1Β) was employed to compare the cellular immune response between infected with EMCs and uninfected O. niloticus. The results indicated a significant increase in TNF- and IL-1Β levels in FBZTs-infected vs un-infected fishes. Importantly, the presence of adult flukes and EMCs led to substantial histological alterations in both experimentally infected pigeons and naturally infected fish tissues. These changes included the necrosis of fish muscle bundles and a pronounced inflammatory reaction with muscular necrosis in the digestive tracts of experimentally infected pigeons.

Sharing is caring? Barcoding suggests co-introduction of dactylogyrid monogeneans with Nile tilapia and transfer towards native tilapias in sub-Saharan Africa.

Invasive Nile tilapias negatively impact native tilapia species through hybridisation and competition. However, the co-introduction of parasites with Nile tilapia, and subsequent changes in parasite communities, are scarcely documented. Monogeneans are known pathogens of cultured Nile tilapia, although little is known about their fate once Nile tilapias establish in new ecosystems. We investigate the parasitological consequences of Nile tilapia introduction on native tilapias in basins in Cameroon, the Democratic Republic of the Congo (DRC), and Zimbabwe, focusing on ectoparasitic dactylogyrids (Monogenea). Using the mitochondrial cytochrome oxidase c subunit I (COI) and nuclear 18S-internal transcribed spacer 1 (18S-ITS1) rDNA region of 128 and 166 worms, respectively, we evaluated transmission of several dactylogyrid species. Parasite spillover from Nile tilapia was detected for Cichlidogyrus tilapiae to Coptodon guineensis in Cameroon, Cichlidogyrus thurstonae to Oreochromis macrochir in the DRC, and Cichlidogyrus halli and C. tilapiae to Coptodon rendalli in Zimbabwe. Parasite spillback to Nile tilapia was detected for Cichlidogyrus papernastrema and Scutogyrus gravivaginus from Tilapia sparrmanii and Cichlidogyrus dossoui from C. rendalli or T. sparrmanii in the DRC, and Cichlidogyrus chloeae from Oreochromis cf. mortimeri and S. gravivaginus from O. macrochir in Zimbabwe. 'Hidden' transmissions (i.e. transmission of certain parasite lineages of species that are naturally present on both alien and native hosts) were detected for C. tilapiae and Scutogyrus longicornis between Nile tilapia and Oreochromis aureus and C. tilapiae between Nile tilapia and Oreochromis mweruensis in the DRC, and Cichlidogyrus sclerosus and C. tilapiae between Nile tilapia and O. cf. mortimeri in Zimbabwe. A high density of Nile tilapia occurring together with native tilapias, and the broad host range and/or environmental tolerance of the transmitted parasites, are proposed as factors behind parasite transmission through ecological fitting. However, continuous monitoring and the inclusion of environmental variables are necessary to understand the long-term consequences of these transmissions on native tilapias and to elucidate other underlying factors influencing these transmissions.

Morpho-molecular characterization of Gyrodactylus parasites of farmed tilapia and their spillover to native fishes in Mexico.

Translocation of fishes for aquaculture has resulted in the co-introduction of some of their parasites. African cichlid fishes, generically called "tilapias" have been introduced worldwide, along with their monogenean parasites. In a nation-wide survey, we characterised monogeneans of the genus Gyrodactylus infecting farmed "tilapia" throughout Mexico. We also collected native fishes around farms, to look for potential parasite spillover from cultured fishes. Monogeneans were identified taxonomically using morphological and molecular characters. Originally African, pathogenic Gyrodactylus cichlidarum was recorded in every farm surveyed, infecting different "tilapia" varieties, as well as three native cichlid fish species. Previously, we had shown that G. cichlidarum also infects native, non-cichlid fishes in Mexico. We also recorded that Gyrodactylus yacatli is widely distributed in Mexico, infecting cultured "tilapia" and native fishes; and present data indicating that this is a further translocated African parasite. A third, unidentified gyrodactylid infected farmed and native fishes in Chiapas, southern Mexico; we describe the new species as Gyrodactylus shinni n. sp., and provide evidence that this is a third monogenean translocated with African fish. The wide distribution of exotic parasites co-introduced with "tilapia" and their spillover to native fishes may have an important impact on the ichthyofauna in Mexico, one the world's megadiverse countries.

Formulation of an exoskeleton degrading bacterial consortium from seafood processing effluent for the biocontrol of crustacean parasite Alitropus typus.

Parasitic infestations on cultured fish due to the crustacean isopod Alitropus typus has been on the rise in recent years, causing large scale mortality, leading to significant economic loss to the farmer. Crustaceans are encased by an exoskeleton composed of chitin, protein and lipid microfibril frameworks, in which calcium carbonate is deposited. A strategy focused on the degradation of the exoskeletal framework utilizing nonpathogenic microorganisms that produce a wide variety of hydrolytic enzymes may be an environment-friendly and safe alternative to control these pests. The present study was aimed to formulate a microbial consortium having chitinase, protease, lipase and urease producing bacteria from seafood processing effluents that can potentially degrade the exoskeleton of A. typus. Based on the qualitative and quantitative assessment of the extracellular enzymes produced by the isolates, a novel consortium was prepared with three strains that were not antagonistic to each other and were nonpathogenic. The chitinase producing - Stenotrophomonas maltophilia and Bacillus altitudinis that produced protease and lipase as well; and non-chitinase producing Klebsiella pneumoniae were taken in the ratio of 1:1:2 respectively (109 CFU/mL). The result showed 100 % mortality of the isopods within five days when applied at a concentration of 2% (v/v) of 107 CFU/mL without any adverse effect on the fish host Oreochromis niloticus. Analysis of the ultrastructural alterations of the parasites by Environmental Scanning Electron microscopy (ESEM) showed noticeable exoskeletal damages. The microbial members of the consortium displayed remarkable chemotactic properties towards A. typus. The results suggest that the microbial consortium acts as a potential parasiticide that can be used for the control of A. typus infestation in aquaculture ponds., thus benefitting the aquaculture industry especially the small-scale farmers.

Molecular Effects of Silver Nanoparticles on Monogenean Parasites: Lessons from Caenorhabditis elegans.

The mechanisms of action of silver nanoparticles (AgNPs) in monogenean parasites of the genus Cichlidogyrus were investigated through a microarray hybridization approach using genomic information from the nematode Caenorhabditis elegans. The effects of two concentrations of AgNPs were explored, low (6 µg/L Ag) and high (36 µg/L Ag). Microarray analysis revealed that both concentrations of AgNPs activated similar biological processes, although by different mechanisms. Expression profiles included genes involved in detoxification, neurotoxicity, modulation of cell signaling, reproduction, embryonic development, and tegument organization as the main biological processes dysregulated by AgNPs. Two important processes (DNA damage and cell death) were mostly activated in parasites exposed to the lower concentration of AgNPs. To our knowledge, this is the first study providing information on the sub-cellular and molecular effects of exposure to AgNPs in metazoan parasites of fish.

Six new species of Cichlidogyrus Paperna, 1960 (Platyhelminthes: Monogenea) from the gills of cichlids (Teleostei: Cichliformes) from the Lomami River Basin (DRC: Middle Congo).

BACKGROUND: Monogenea van Beneden, 1858 is a group of parasitic flatworms, commonly found infecting bony fish. Several genera, such as Cichlidogyrus Paperna, 1960, are reported to include potential pathogenic species that can negatively impact aquaculture fish stocks. They can switch from introduced to native fish and vice versa. In Africa (and all over the world), fish species belonging to Cichlidae are often kept in aquaculture and represent a major source of food. Thus, research on the biodiversity and occurrence of monogenean species on these fish is of importance for aquaculture and conservation. The present study is a survey of the diversity of species of Cichlidogyrus in the south of the Democratic Republic of the Congo (DRC) on three cichlid species: Orthochromis sp. 'Lomami', Serranochromis cf. macrocephalus, and Tilapia sparrmanii Smith, 1840. METHODS: Specimens of Cichlidogyrus were isolated from the gills and mounted on glass slides with Hoyer's medium. The genital and haptoral hard parts were measured and drawn using interference contrast. RESULTS: In total, six species of Cichlidogyrus were found, all new to science: C. bulbophallus n. sp. and C. pseudozambezensis n. sp. on S. cf. macrocephalus, C. flagellum n. sp. and C. lobus n. sp. on T. sparrmanii, C. ranula n. sp. on S. cf. macrocephalus and Orthochromis sp. 'Lomami', and C. maeander n. sp. found on Orthochromis sp. 'Lomami' and T. sparrmanii. The first four species are considered to be strict specialists, C. ranula n. sp. an intermediate generalist and C. maeander n. sp. a generalist. These parasite species show morphological similarities to species found in the Lower Guinea and Zambezi ichthyofaunal provinces, which might be explained by past river capture events between river systems of the Congo Province and both these regions. CONCLUSIONS: Serranochromis cf. macrocephalus and Orthochromis sp. 'Lomami' can harbour respectively three and two species of Cichlidogyrus, all described in this study. Tilapia sparrmanii can harbour seven species, of which three are described in the present study. These results highlight the species diversity of this parasite genus in the Congo Basin.

Monogenean parasites from the stomach of Oreochromis mossambicus from South Africa: two new species of Enterogyrus (Dactylogyridae: Ancyrocephalinae).

The study provides descriptions of two new species of Enterogyrus coexisting in the stomach of the Mozambique tilapia, Oreochromis mossambicus (Peters). Enterogyrus multispiralis n. sp. and Enterogyrus mashegoi n. sp. were collected from hosts sampled at Nwanedi-Luphephe Dam, Limpopo River System, South Africa. The two new species can be differentiated from other members of the genus based on the spirality characteristics of the cirrus. Enterogyrus multispiralis n. sp. has an unique 8/9-2-4 cirrus spiral formula. The length of the cirrus and its spriral formula 5-2-3 make E. mashegoi n. sp. morphometrically unique from other Enterogyrus spp. Sequences of the nuclear ribosomal DNA partial 18S and internal transcribed spacer (ITS1) and 28S were obtained and compared with available sequences of Enterogyrus in GenBank. This is the first record of data on 18S rDNA region of Enterogyrus spp. A phylogenetic comparison was conducted, which included all data available for Enterogyrus spp., but this was limited to 28S data. The closest species to both new species of the present study was an undescribed Enterogyrus sp. 2 from Sarotherodon galilaeus (Linnaeus) described from Senegal (i.e. 2.1 and 2.9% uncorrected pairwise genetic distance to E. multispiralis n. sp. and E. mashegoi n. sp., respectively). These species represent new records for Africa resulting in a total number of 12 described valid species.

Description of a new species of Dermoergasilus Ho & Do, 1982 (Copepoda: Ergasilidae) from the redbelly tilapia Coptodon zillii (Gervais) (Perciformes: Cichlidae) in Basrah, southern Iraq.

A new species of Dermoergasilus Ho & Do, 1982 (Copepoda: Ergasilidae) parasitic on the gills of the redbelly tilapia Coptodon zillii (Gervais) from Basrah, southern Iraq, is described. Dermoergasilus cichlidus n. sp. is morphologically similar to D. longiabdominalis El-Rashidy & Boxshall, 2001 in the body length to width ratio, the swimming legs armature, the shape of the urosome and the small slightly spiniform seta on the exopodal segment of leg 5. However, the main differences are the presence of long setae on the endopod of leg 1 in D. cichlidus n. sp. (vs relatively short setae); the inner apical spine on the tip of the endopod of leg 1 being only slightly longer than the outer apical spine (vs inner apical spine about twice as long as the outer); the first interpodal sternite ornamented with spinules (vs interpodal sternites not ornamented); and the caudal rami and anal somite of equal length (vs caudal rami length c.2/3 of the length of the anal somite). Dermoergasilus occidentalis can be distinguished from D. cichlidus n. sp. by the relative length of the antennal segments, the absence of a minute terminal spine on the digital process of the caudal ramus and by differences in the mouth parts.

Lipidomics for wildlife disease etiology and biomarker discovery: a case study of pansteatitis outbreak in South Africa.

INTRODUCTION: Lipidomics is an emerging field with great promise for biomarker and mechanistic studies due to lipids diverse biological roles. Clinical research applying lipidomics is drastically increasing, with research methods and tools developed for clinical applications equally promising for wildlife studies. OBJECTIVES: Limited research to date has applied lipidomics, especially of the intact lipidome, to wildlife studies. Therefore, we examine the application of lipidomics for in situ studies on Mozambique tilapia (Oreochromis mossambicus) in Loskop Dam, South Africa. Wide-scale mortality events of aquatic life associated with an environmentally-derived inflammatory disease, pansteatitis, have occurred in this area. METHODS: The lipidome of adipose tissue (n = 31) and plasma (n = 51) from tilapia collected from Loskop Dam were characterized using state of the art liquid chromatography coupled to high-resolution tandem mass spectrometry. RESULTS: Lipid profiles reflected pansteatitis severity and were significantly different between diseased and healthy individuals. Over 13 classes of lipids associated with inflammation, cell death, and/or oxidative damage were upregulated in pansteatitis-affected adipose tissue, including ether-lipids, short-chained triglyceride oxidation products, sphingolipids, and acylcarnitines. Ceramides showed a 1000-fold increase in the most affected adipose tissues and were sensitive to disease severity. In plasma, triglycerides were found to be downregulated in pansteatitis-affected tilapia. CONCLUSION: Intact lipidomics provided useful mechanistic data and possible biomarkers of pansteatitis. Lipids pointed to upregulated inflammatory pathways, and ceramides serve as promising biomarker candidates for pansteatitis. As comprehensive coverage of the lipidome aids in the elucidation of possible disease mechanisms, application of lipidomics could be applied to the understanding of other environmentally-derived inflammatory conditions, such as those caused by obesogens.

Molecular and morphological characterisation of four diplostomid metacercariae infecting Tilapia sparrmanii (Perciformes: Cichlidae) in the North West Province, South Africa.

Despite their pathogenic effects on fish, the diversity of trematodes from the family Diplostomidae remains vastly unexplored in Africa and specifically South Africa. To date, only six species of diplostomids have been reported from freshwater fishes in this country, with only two species being molecularly characterised. In this study, combined morphological and molecular analyses were used to identify and describe metacercariae of the Diplostomidae (Digenea) parasitising banded tilapia Tilapia sparrmanii (Perciformes: Cichlidae) collected within the North West Province, South Africa. Metacercariae found on the body surface and muscles of the fish were separated into four groups based on the infection site, the colour of the cysts and the morphology of excysted specimens. Isolates from each group were further identified through molecular analyses. Comparative analyses of the newly generated 28S rDNA, ITS1-5.8S-ITS2 and cox1 sequences revealed the presence of four species of which three were identified as Bolbophorus sp. 3 (28S rDNA, ITS1-5.8S-ITS2 and cox1), Posthodiplostomum sp. 9 (28S rDNA and ITS1-5.8S-ITS2) and Uvulifer sp. 4 (28S rDNA, ITS1-5.8S-ITS2 and cox1), respectively, and the fourth species belonging to the Diplostomidae gen. sp. (28S rDNA, ITS1-5.8S-ITS2 and cox1). Morphology of metacercariae of Posthodiplostomum sp. was compared with metacercariae of this genus previously reported in fishes in Africa. This study presents the first molecular data for species of Bolbophorus Dubois, 1935, Posthodiplostomum Dubois, 1936 and Uvulifer Yamaguti, 1934 from Africa, and it highlights the need for future research on the diversity of diplostomid parasites in South Africa and in Africa as whole.

Monogenean fauna of alien tilapias (Cichlidae) in south China.

Tilapias are important aquaculture fishes that have been introduced widely all over the world, often carrying their monogenean parasites with them. An extensive investigation on monogeneans of invasive tilapias was conducted in 19 natural water sources in south China between July 2015 and December 2017. We found nine known species of monogeneans, i.e., Enterogyrus coronatus, E. malmbergi, Cichlidogyrus cirratus, C. halli, C. sclerosus, C. thurstonae, C. tilapiae, Scutogyrus longicornis, Gyrodactylus cichlidarum, and one unknown Gyrodactylus species. In addition to reporting ten new hosts and four new geographical records, we observed new morphological characteristics of these species. Observation on living specimens of Enterogyrus spp. demonstrated that these two species have characteristic opisthaptoral retraction capacities, while the opisthaptor glands were not observed in our specimens of E. coronatus and E. malmbergi. The morphological differences of the accessory piece of the male copulatory complex between C. cirratus and C. mbirizei (character for species differentiation) could result from the observation at different perspectives, which indicates that C. mbirizei is likely a synonym of C. cirratus. A more detailed structure of the sclerotized parts of Cichlidogyrus spp. and S. longicornis were revealed by scanning electron microscopy. As was the case for the monogeneans found on alien tilapias from other geographic regions, the present study confirmed the high potential of these monogeneans to establish populations in new habitats.

Morphological and molecular characterization of a novel myxosporean parasite Myxobolus bejeranoi n. sp. (Cnidaria: Myxosporea) from hybrid tilapia in Israel.

Myxosporean infections can cause severe damage to commercially grown tilapia. Here, we report a novel myxosporean that was found in gills of Oreochromis aureus male × Oreochromis niloticus female, which is an important aquaculture tilapia hybrid in Israel. Three-month-old fish were found to have cysts located in gill muscle tissue, which were filled with both immature and mature spores. Affected fish displayed higher mortality rate. Spore dimensions (10.8 ± 0.7 µm length × 6.8 ± 0.6 µm width) and molecular characterization using 18S ribosomal DNA revealed that the unknown parasite belongs in the Myxobolus clade. Based on the infection site, spore morphology and molecular characterization, we describe this parasite as Myxobolus bejeranoi n. sp. (MF401455). Phylogenetic analysis showed that the new species is most closely related to two Myxobolus spp. from O. niloticus in Egypt and Ghana.

Redescription of Austrodiplostomum compactum (Trematoda: Diplostomidae) from its Type Host and Locality in Venezuela, and of Austrodiplostomum mordax from Argentina.

Austrodiplostomum compactum from Nannopterum brasilianus, and its metacercaria from Geophagus sp. and Oreochromis mossambicus captured (1979) at its type locality, Valencia Lake, Venezuela, by the author, are redescribed. The adult is characterized by its large body size, and an oral sucker smaller than the pharynx. The metacercaria has a similar body size as the adult, and the small genital primordia occupy 4.1-7.3% of body length. Experimental infections in chickens with metacercariae of Diplostomulum mordax from brains of Odonthestes bonariensis, captured (2015) at Dique Paso de las Piedras, near Bahia Blanca City, Buenos Aires Province, Argentina, resulted in 10 adults 5 days postexposure. These adults correspond to Austrodiplostomum mordax as described from N. brasilianus at Lacombe Lagoon, Buenos Aires Province, and differ from A. compactum in their smaller body size, and an oral sucker larger than the pharynx. The metacercaria has a similar body size as the adult and differs mainly in that the larger genital primordia occupy 11.6-13.8% of body length. The status of earlier published Austrodiplostomum species in the American continent is discussed in view of available morphological and molecular data. A lectotype of A. mordax is here designated, and Austrodiplostomum ostrowskiae is considered as a new synonym of A. compactum.

Triple trouble? Invasive poeciliid fishes carry the introduced tilapia pathogen Gyrodactylus cichlidarum in the Mexican highlands.

As part of ongoing surveys of the gyrodactylid parasite fauna of freshwater fishes in Mexico, we recorded the infection of three species of poeciliids (Poecilia mexicana, Poeciliopsis gracilis, and Pseudoxiphophorus bimaculatus [syn.=Heterandria bimaculata]) with Gyrodactylus cichlidarum, a monogenean parasite of cichlid fishes, which has been co-introduced globally with its translocated, African "tilapia" hosts. This tilapia pathogen was found on poeciliid fishes both within their native distribution range in the Gulf of Mexico slope, as well as on invasive species artificially introduced to the Mexican highlands, to rivers draining into the Pacific Ocean. Identity of G. cichlidarum was confirmed by morphological and molecular analyses. Prevalence and abundance of infection were low, but this is the first record of G. cichlidarum infecting poeciliids (Cyprinodontiformes), which are distantly related to this parasite's primary cichlid fish hosts (Perciformes). This study provides evidence that G. cichlidarum, a recognized pathogen which has been co-introduced globally with its cichlid fish hosts for aquacultural purposes, is able to infect non-related poeciliid fishes inhabiting water bodies adjacent to tilapia farms, thereby potentially increasing its ability to disperse between farms and different river basins. It is of particular concern that G. cichlidarum was found on poeciliids, as these invasive fishes have been introduced worldwide and could act as carriers for this parasite known to induce significant mortality of farmed tilapias - globally, the second most important freshwater aquaculture fish group, after the carps.

Redescription of Cichlidogyrus tiberianus Paperna, 1960 and C. dossoui Douëllou, 1993 (Monogenea: Ancyrocephalidae), with special reference to the male copulatory organ.

The flatworms of the genus Cichlidogyrus Paperna, 1960 (Monogenea: Ancyrocephalidae) are gill parasites of freshwater fish, affecting predominantly the family Cichlidae. Cichlidogyrus tiberianus Paperna, 1960 and Cichlidogyrus dossoui Douëllou, 1993 are among the most widely distributed species of the genus, occurring in several African river basins and infecting many different host species, including the economically important Nile tilapia Oreochromis niloticus (Linnaeus) and redbreast tilapia Coptodon rendalli (Boulenger). Despite their wide distribution, C. tiberianus and C. dossoui have so far been studied only by light microscopy. In this paper they are redescribed on the basis of scanning electron microscopy of newly-collected material. The new material was obtained from redbreast tilapia caught in the Luapula River (D. R. Congo). The haptoral sclerites and genitalia are redescribed and illustrated in detail. Special attention is given to the complex morphology of the male copulatory organ.

A case of complete loss of gill parasites in the invasive cichlid Oreochromis mossambicus.

This study investigates the recent evolution of a rich parasite community associated with one of the world's most invasive species, the cichlid fish Oreochromis mossambicus. Populations from the species' native range (Mozambique) are compared to a population from New Caledonia (Wester Pacific), an island where the species was introduced in 1954. The results support the complete local extinction of the gill parasite community in the course of the invasion process. Up to six gill parasite species per locality were documented in the O. mossambicus native range, and previous surveys consistently reported at least one parasite species introduced along African cichlid species established out of Africa. The absence of parasites in New Caledonia is therefore exceptional. This can be attributed to local factors, such as a strong initial population bottleneck, the likely absence of multiple host introductions, and the frequent occurrence of brackish watersheds that might enhance the probability for natural deparasitation.

Susceptibility, metacercarial burden, and mortality of juvenile silver barb, common carp, mrigal, and tilapia following exposure to Haplorchis taichui.

Fish-borne zoonotic trematodes (FZT) including heterophyids and opisthorchiids are prevalent in native and aquaculture fish in Southeast Asia. FZT are reported highly prevalent in juvenile aquaculture fish that belonged to the family Heterophyidae, particularly Haplorchis taichui. Aquaculture fish are reported to have varying levels of natural infection with H. taichui, but data for their susceptibility as well as resistance to infection are not available. The aim of this study was to determine the susceptibility of five aquaculture fish to H. taichui. Experimental infections were performed by exposing fish individually to 0 (control), 50, 100, or 200 H. taichui cercariae for 12 h. Metacercarial burden was measured at 45 days postinfection. Three out of five fish species, silver barb (Barbonymus gonionotus), common carp (Cyprinus carpio), and mrigal (Cirrhinus mrigala), were highly susceptible to H. taichui infection with percentage ranging from 93.33 to 100%. The Nile and red tilapia were not susceptible to infection. Among the susceptible fish species, silver barb had higher intensity of H. taichui metacercariae than common carp and mrigal (P < 0.001). Metacercarial burden significantly correlated with the dose of cercarial infection (P < 0.001). Our findings that common aquaculture fish species have varying degrees of susceptibility to H. taichui infection provide important information to reduce parasite transmission in aquaculture fish.

Redescription of Clinostomum phalacrocoracis metacercariae (Digenea: Clinostomidae) in cichlids from Lake Kinneret, Israel.

Clinostomidae are digeneans characterized by a complex taxonomic history, continuously under revision based on both morphological and molecular analysis. Among the 14 species considered valid so far Clinostomum phalacrocoracis has been well described only at the adult stage, whereas the morphology of the metacercarial stage has been reported only once. During a parasitological survey carried out on 262 wild cichlids sampled from Lake Kinneret (Israel) metacercariae referable to C. phalacrocoracis were found in 18 fingerlings. In this study, we report this clinostomid species for the first time in wild fish from Israel describing the metacercarial stage of Clinostomum phalacrocoracis, coupling its morphological description with molecular analysis carried out on ITS rDNA and COI mtDNA sequences.

Insights into regulatory molecules of intestinal epithelial cell turnover during experimental infection by Heterophyes heterophyes.

Heterophyiasis is an intestinal disease that remains endemic in many parts of the world, particularly the Nile Delta of Egypt and Southeast Asia, yet the populations at risk of infection expand throughout the world. The main histopathological feature of infection is villous atrophy, but the underlying factors are not well understood. Apoptosis of the villous epithelial cells was previously reported to be enhanced during intestinal parasitic infections; however, the role of Heterophyes heterophyes on enterocyte apoptosis was to be explored. Therefore, intestinal sections from mice experimentally infected with H. heterophyes were studied histopathologically and immunohistochemically for caspase-3 and NF-κB and compared to non-infected control mice. Atrophic villi covered by poorly differentiated epithelial cells were observed in the 2nd week post-infection. Also, we noted marked hyperplasia of the intestinal crypts with abundant inflammatory cellular infiltrate in the lamina propria, as well as apoptosis of cells lining the intestinal villi. Both caspase-3 and NF-κB showed positive staining in the intestinal epithelial cells with varying grades of intensity over the length of infection. Caspase-3 expression rose at the 2nd week p.i. then decreased over time, whereas NF-κB expression showed progressive increase throughout the weeks of infection. In conclusion, caspase-3 activation may be an important factor in the apoptotic pathway in early heterophyiasis, and, on the other hand, NF-κB seems to play a role in protecting the intestinal cells from excessive apoptosis. These observations may help open new avenues for tissue protective therapies that avoid or control the deleterious processes of apoptosis in various inflammatory conditions.