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International Journal For Parasitology.... Aug 2020Harbour porpoises () are the only native cetacean species in the German North and Baltic Seas and the final host of (.) , which infects their first and second gastric...
Harbour porpoises () are the only native cetacean species in the German North and Baltic Seas and the final host of (.) , which infects their first and second gastric compartments and may cause chronic ulcerative gastritis. belongs to the family Anisakidae (Ascaridoidea, Rhabditida) as well as the phocine gastric nematode species (.) and (.) . These nematode species are the main causative agents for the zoonosis anisakidosis. The taxonomy of these genus with life cycles including crustaceans and commercially important fish is complex because of the formation of sibling species. Little is known about anisakid species infecting porpoises in the study area. Mature nematodes and larval stages are often identifiable only by molecular methods due to high morphological and genetic similarity. The restriction fragment length polymorphism (RFLP) method is an alternative to sequencing and was applied to identify anisakid nematodes found in harbour porpoises from the North Sea, Baltic Sea and North Atlantic to species level for the first time. In the study areas, five gastric nematodes from different harbour porpoise hosts were selected to be investigated with restriction enzymes I, I and III, which were able to differentiate several anisakid nematode species by characteristic banding patterns. s. s. was the dominant species found in the North Sea and Baltic porpoises, identified by all three restriction enzymes. Additionally, a hybrid of . s. s. and . was determined by I in the North Sea samples. Within the North Atlantic specimens, . s. s., . s. s. and (.) were identified by all enzymes. This demonstrates the value of the RFLP method and the chosen restriction enzymes for the species identification of a broad variety of anisakid nematodes affecting the health of marine mammals.
PubMed: 32489854
DOI: 10.1016/j.ijppaw.2020.05.004 -
Parasites & Vectors Feb 2020Red Vent Syndrome (RVS), a haemorrhagic inflammation of the vent region in Atlantic salmon, is associated with high abundance of Anisakis simplex (s.s.) third-stage...
BACKGROUND
Red Vent Syndrome (RVS), a haemorrhagic inflammation of the vent region in Atlantic salmon, is associated with high abundance of Anisakis simplex (s.s.) third-stage larvae (L3) in the vent region. Despite evidence suggesting that increasing A. simplex (s.s.) intensity is a causative factor in RVS aetiology, the definitive cause remains unclear.
METHODS
A total of 117 Atlantic salmon were sampled from commercial fisheries on the East, West, and North coasts of Scotland and examined for ascaridoid parasites. Genetic identification of a subsample of Anisakis larvae was performed using the internal transcribed spacer (ITS) region of ribosomal DNA. To assess the extent of differentiation of feeding grounds and dietary composition, stable isotope analysis of carbon and nitrogen was carried out on Atlantic salmon muscle tissue.
RESULTS
In the present study, the obtained ITS rDNA sequences matched A. simplex (s.s.) sequences deposited in GenBank at 99-100%. Not all isolated larvae (n = 30,406) were genetically identified. Therefore, the morphotype found in this study is referred to as A. simplex (sensu lato). Anisakis simplex (s.l.) was the most prevalent (100%) nematode with the highest mean intensity (259.9 ± 197.3), in comparison to Hysterothylacium aduncum (66.7%, 6.4 ± 10.2) and Pseudoterranova decipiens (s.l.) (14.5%, 1.4 ± 0.6). The mean intensity of A. simplex (s.l.) represents a four-fold increase compared to published data (63.6 ± 31.9) from salmon captured in Scotland in 2009. Significant positive correlations between A. simplex (s.l.) larvae intensities from the body and the vent suggest that they play a role in the emergence of RVS. The lack of a significant variation in stable isotope ratios of Atlantic salmon indicates that diet or feeding ground are not driving regional differences in A. simplex (s.l.) intensities.
CONCLUSIONS
This paper presents the most recent survey for ascaridoid parasites of wild Atlantic salmon from three coastal regions in Scotland. A significant rise in A. simplex (s.l.) intensity could potentially increase both natural mortality rates of Atlantic salmon and possible risks for salmon consumers due to the known zoonotic role of A. simplex (s.s.) and A. pegreffii within the A. simplex (s.l.) species complex.
Topics: Animals; Anisakiasis; Anisakis; DNA, Intergenic; DNA, Ribosomal; Fish Diseases; Larva; Salmo salar; Scotland; Seafood
PubMed: 32051019
DOI: 10.1186/s13071-020-3942-5 -
Revista Brasileira de Parasitologia... 2019The current parasitological study was carried out to investigate helminth parasites infecting the Red spot emperor Lethrinus lentjan inhabiting Hurghada City at the Gulf...
The current parasitological study was carried out to investigate helminth parasites infecting the Red spot emperor Lethrinus lentjan inhabiting Hurghada City at the Gulf of Suez, Red Sea, Egypt. Third-stage larvae of nematode parasite was isolated from the intestine as well as body cavity of the examined fish. Light and scanning electron microscopy revealed that this parasite belonged to Anisakidae family within the genus Pseudoterranova. The present species is named Pseudoterranova decipiens based on the presence of triangular mouth aperture with prominent boring teeth and soft swellings of the cuticle, long muscular esophagus, ventrally excretory pore, and narrow transverse slit of anal opening followed by a short mucron. The morphological characteristics of this species were confirmed by molecular analysis of 18S rDNA gene region of the present parasite. It demonstrated a close identity ≥89% with taxa under family Anisakidae, 85% with Raphidascarididae, and 79-84% with Toxocaridae. A preliminary genetic comparison between gene sequence of the present parasite and other oxyurid species placeed it as a putative sister taxon to other Pseudoterranova decipiens described previously. This study demonstrated that the 18S rDNA gene region of Pseudoterranova decipiens yielded a unique sequence that confirmed its taxonomic position in Anisakidae.
Topics: Animals; DNA, Ribosomal; Egypt; Fish Diseases; Fishes; Indian Ocean; Microscopy, Electron, Scanning; Nematoda; Phylogeny; RNA, Ribosomal, 18S
PubMed: 31460624
DOI: 10.1590/S1984-29612019057 -
Scientific Reports Jul 2019Environmental niche modelling is an acclaimed method for estimating species' present or future distributions. However, in marine environments the assembly of...
Environmental niche modelling is an acclaimed method for estimating species' present or future distributions. However, in marine environments the assembly of representative data from reliable and unbiased occurrences is challenging. Here, we aimed to model the environmental niche and distribution of marine, parasitic nematodes from the Pseudoterranova decipiens complex using the software Maxent. The distribution of these potentially zoonotic species is of interest, because they infect the muscle tissue of host species targeted by fisheries. To achieve the best possible model, we used two different approaches. The land distance (LD) model was based on abiotic data, whereas the definitive host distance (DHD) model included species-specific biotic data. To assess whether DHD is a suitable descriptor for Pseudoterranova spp., the niches of the parasites and their respective definitive hosts were analysed using ecospat. The performance of LD and DHD was compared based on the variables' contribution to the model. The DHD-model clearly outperformed the LD-model. While the LD-model gave an estimate of the parasites' niches, it only showed the potential distribution. The DHD-model produced an estimate of the species' realised distribution and indicated that biotic variables can help to improve the modelling of data-poor, marine species.
Topics: Animals; Aquatic Organisms; Ecosystem; Fisheries; Fishes; Host Specificity; Parasites; Species Specificity
PubMed: 31285445
DOI: 10.1038/s41598-019-46127-6 -
International Journal For Parasitology Jul 2019Human toxocariasis is a zoonosis resulting from the migration of larval stages of the dog parasite Toxocara canis into the human paratenic host. Despite its well-known...
Human toxocariasis is a zoonosis resulting from the migration of larval stages of the dog parasite Toxocara canis into the human paratenic host. Despite its well-known limitations, serology remains the most important tool to diagnose the disease. Our objective was to employ camelid single domain antibody fragments also known as nanobodies (Nbs) for a specific and sensitive detection of Toxocara canis excretory/secretory (TES) antigens. From an alpaca immune Nb library, we retrieved different Nbs with specificity for TES antigens. Based on ELISA experiments, these Nbs did not show any cross-reactivity with Ascaris lumbricoides, Ascaris suum, Pseudoterranova decipiens, Anisakis simplex and Angiostrongylus cantonensis larval antigens. Western blot and immunocapturing revealed that Nbs 1TCE39, 1TCE52 and 2TCE49 recognise shared epitopes on different components of TES antigen. The presence of disulphide bonds in the target antigen seems to be essential for recognition of the epitopes by these three Nbs. Three separate sandwich ELISA formats, using monovalent and bivalent Nbs, were assessed to maximise the detection of TES antigens in solution. The combination of biotinylated, bivalent Nb 2TCE49 on a streptavidin pre-coated plate to capture TES antigens, and Nb 1TCE39 chemically coupled to horseradish peroxidase for detection of the captured TES antigens, yielded the most sensitive ELISA with a limit of detection of 0.650 ng/ml of TES antigen, spiked in serum. Moreover, the assay was able to detect TES antigens in sera from mice, taken 3 days after the animals were experimentally infected with T. canis. The specific characteristics of Nbs make this ELISA not only a promising tool for the detection of TES antigens in clinical samples, but also for a detailed structural and functional study of TES antigens.
Topics: Animals; Antibodies, Helminth; Antigens, Helminth; Blotting, Western; Camelids, New World; Electrophoresis, Polyacrylamide Gel; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Mice; Microspheres; Plasmids; Polymerase Chain Reaction; Single-Domain Antibodies; Toxocara canis
PubMed: 31150611
DOI: 10.1016/j.ijpara.2019.03.004 -
Parasitology Research Jul 2019The consumption of raw or inadequately cooked marine fish can lead to several disorders caused by the ingestion of viable anisakid nematodes. Although anisakid larvae...
The consumption of raw or inadequately cooked marine fish can lead to several disorders caused by the ingestion of viable anisakid nematodes. Although anisakid larvae can be killed by subzero temperatures, making freezing an important control measure for this potential health hazard, these parasites can survive freezing under some conditions. Therefore, the aim of the present study was to experimentally evaluate the time-temperature conditions needed to kill Anisakis simplex and Pseudoterranova spp. The effectiveness of freezing was tested on two species of fish: cod, Gadus morhua from the North Atlantic, and herring, Clupea harengus membras from the southern Baltic Sea. Samples, which comprised skinless fillets of cod (n = 40) with visible parasites and whole herring (n = 240), were separately frozen at - 15, - 18, or - 20 °C for 24 h, or at - 20 °C for 48 h in the single-compressor freezer and at - 20, - 25, or - 35 °C for 24 h in the double-compressor freezer. After thawing, parasites were stained with malachite green and examined under the microscope for viability. All A. simplex and Pseudoterranova spp. larvae in cod fillets died at a temperature of - 15 °C or lower. However, freezing did not kill all the A. simplex larvae in whole herring: spontaneous movement of these parasites was observed in samples stored in the single-compressor freezer at - 15, - 18, and - 20 °C over 24 h. Our results demonstrate that the freezing procedure must consider both the capability of the freezing device and the nature of the fish product to ensure consumer safety.
Topics: Animals; Anisakis; Ascaridoidea; Cold Temperature; Fish Diseases; Fishes; Food Safety; Foodborne Diseases; Freezing; Gadus morhua; Humans; Larva
PubMed: 31098726
DOI: 10.1007/s00436-019-06339-1