Anisakis Simplex Sensu Lato Research Articles

On survival of the larvae of marine parasitic nematode <i>Anisakis simplex</i> sensu lato (Rudolphi, 1809) in the fresh waters

Survival of the larvae of marine parasitic nematode Anisakis simplex sensu lato (Rudolphi, 1809) in the fresh waters was monitored. In total, 37 live larvae of A. simplex s.l. were sampled from charr Salvelinus malma caught in the lower reaches of the Kamchatka River. The larvae were kept in the freshwater refreshed everyday, without food, their viability was examined daily at 9 a.m. All larvae were still alive in the 4 th day (100 %); 2.7 % were alive after 9 days in freshwater, but all of them were died after 10 days. Dependence of the number of dead larvae on the time of their exposition in the freshwater is well approximated by von Bertalanffy equation (R 2 = 0.996). Besides, viability of A. simplex s.l. larvae in the bodies of dead sockeye spawners was examined at the spawning grounds in Lake Azabachye: the larvae were alive in the body cavity of fish that died at least 3–5 days ago and remained alive at least 3 days more being placed in the freshwater. The larvae of marine nematode A. simplex s.l. are able to enter to the fresh waters with migratory fish. Following to our results, they can survive there for several days. So, measures for disinfecting against A. simplex s.l. are recommended for the freshwater fish caught in the water bodies connected with the marine environment.

Genome-wide analysis of Anisakis simplex sensu lato: the role of carbohydrate metabolism genes in the parasite’s development

Anisakis simplex sensu lato is a parasitic nematode which can cause gastric symptoms and/or allergic reactions in humans who consume raw and undercooked fish. Anisakiasis poses a growing health problem around the globe because it causes non-specific symptoms and is difficult to diagnose. This genome-wide study was undertaken to expand our knowledge of A. simplex s.l. at the molecular level and provide novel data for biological and biotechnological research into the analyzed species and related nematodes. A draft genome assembly of the L3 stage of A. simplex s.l. was analyzed in detail, and changes in the expression of carbohydrate metabolism genes during the parasite's life cycle were determined. To our knowledge, this is the first genome to be described for a parasitic nematode of the family Anisakidae to date. We identified genes involved in parasite-specific pathways, including carbohydrates metabolism, apoptosis and chemo signaling. A total of 7607 coding genes were predicted. The genome of A. simplex s.l. is highly similar to genomes of other parasitic nematodes. In particular, we described a valuable repository of genes encoding proteins of trehalose and glycogen metabolism, and we developed the most comprehensive data set relating to the conversion of both saccharides which play important roles during the parasite's life cycle in a host environment. We also confirmed that trehalose is synthesized at the expense of glycogen. Trehalose anabolism and glycogen catabolism were the predominant processes in stages L4 and L5, which could confirm our and other authors’ previous reports that trehalose is synthesized at the expense of glycogen. The A. simplex s.l. genome provides essential data for post-genomic research into the biology of gastrointestinal and allergic anisakiasis in humans and the biology of other important parasitic helminths.

Population genetic analysis of Anisakis simplex s.l. and Anisakis pegreffii (Nematoda, Anisakidae) from parapatric areas and their contact zone

Genetic markers (ribosomal DNA and mitochondrial DNA) were used for molecular dissection of the Anisakis simplex sensu lato (s.l). complex populations. Host fish were caught off Moroccan coasts, where only Anisakis pegreffii is present, the sympatric area comprising Spanish coasts, and the Little Sole Bank fishing area from Nordeast Atlantic Ocean where the only present species is A. simplex sensu stricto(s.s.). Sequence variations in the amplification products were then assessed indirectly by digestion with restriction endonucleases or directly by sequencing for 623 L3 larvae. The sequences were used to infer the relationships between the two species under study using various methodological approaches. We reveal the high genetic diversity of Anisakis simplex s.s. and A. pegreffii in both mitochondrial and nuclear genes. We detected 10 and 2 fixed differences between A. simplex s.s and A. pegreffii in the Cox2 and ITS1, respectively. We found a proportion of putative hybrids below 20% with similar figures on the Atlantic and Mediterranean coasts. Moroccan hybrids were more similar to A. pegreffii reflecting backcrosses between these mixed genotypes and his ancestor A. pegreffii. We discuss the possible interpretation of these putative hybrids.

Haemoglobin, a new major allergen of Anisakis simplex

Gastro-allergic anisakiasis and Anisakis sensitisation associated chronic urticaria are diseases which differ in their IgE and IgG4 responses against both crude extract and specific allergens. Anisakis and Ascaris are closely related nematodes that usually cause problems with specificity in immunodiagnostics. In this study we measured IgE and IgG4 antibodies against Anisakis simplex sensu lato (s. l.) and Ascaris suum haemoglobins in sera of 21 gastro-allergic anisakiasis and 23 chronic urticaria patients. We used a capture ELISA with the anti-Anisakis haemoglobin monoclonal antibody 4E8g, which also recognises Ascaris haemoglobin. In addition, we determined specific IgE and IgG4 to both nematodes by indirect ELISA and immunoblotting. Anti-A. simplex s. l. haemoglobin IgE and IgG4 levels were higher in gastro-allergic anisakiasis than in chronic urticaria patients (P=0.002 and 0.026, respectively). Surprisingly, no patient had detectable IgE levels against A. suum haemoglobin. Finally, we carried out an in silico study of the B-cell epitopes of both haemoglobin molecules. Five epitopes were predicted in Anisakis pegreffii and four in A. suum haemoglobin. The epitope propensity values of Anisakis haemoglobin in the equivalent IgE binding region of the allergenic haemoglobin Chi t 1 from Chironomus thummi, were higher those of the Ascaris haemoglobin. In conclusion, we describe A. simplex haemoglobin as a new major allergen (Ani s 13), being recognised by a large number (64.3%) of sensitised patients and up to 80.9% in patients with gastro-allergic anisakiasis. The presence of a specific epitope and the different values of epitope propensity between Anisakis and Ascaris haemoglobin could explain the lack of cross-reactivity between the two molecules. The absence of IgE reactivity to Ascaris haemoglobin in Anisakis patients makes Anisakis haemoglobin (Ani s 13) a potential candidate for developing more specific diagnosis tools.

Increase in parasite burden and associated pathology in harbour porpoises (Phocoena phocoena) in West Greenland

Knowledge about parasitism in harbour porpoises and their health status around Greenland is scarce. This study provides knowledge about the poorly studied cetacean in its rapidly changing environment. Parasites and pathological findings in 20 harbour porpoises (Phocoena phocoena) hunted in waters around West Greenland are presented. Carcasses were dissected, and parasitological, histological and bacteriological investigations were carried out. Protozoa (Sarcocystis sp.), Nematoda (Halocercus invaginatus, Stenurus minor, Anisakis simplex sensu lato (s.l.), Crassicauda sp.), Trematoda (Campula oblonga) and Cestoda (Phyllobothrium delphini, Monorygma grimaldii) were found. Parasitic infection of the peribullar cavity and lung with pseudaliid nematodes was found in most animals. Sixty per cent of the porpoises were infected with stomach worms, and trematodes were present in liver and pancreas of 90 and 30 % of the porpoises, respectively. Crassicauda sp. was isolated from perimuscular fascia in 45 % of the animals. This is the first record of tetraphyllidean merocercoids in harbour porpoises. M. grimaldii and P. delphini were found in blubber layer of 15 % and abdominal cavity of 50 % of the porpoises. Bronchopneumonia, gastritis, cholangitis, pancreatitis and panniculitis were almost exclusively associated with parasitic infection and usually mild. Compared with a previous study of Greenlandic porpoises from 1995, a significant increase in severity of parasitic infections and the emergence of new parasite species were observed, most likely associated with changes in diet, influenced by increasing sea temperatures and receding ice cover.

Molecular characterization and comparison of four Anisakis allergens between Anisakis simplex sensu stricto and Anisakis pegreffii from Japan

It remains unclear whether allergens are the same among the sibling species of Anisakis simplex sensu lato. This study was carried out to compare the amino acid sequences of three major (Ani s 1, 2 and 12) and one minor (Ani s 9) Anisakis allergens between A. simplex s.s. and Anisakis pegreffii. We found 2 (out of 163), 1 (out of 869), and 29 (out of 266) amino acid variable sites for Ani s 1, 2, and 12, respectively. However, as both intra- and inter-species variations were present at the same amino acid positions, no amino acid variations clearly distinguished the two sibling species. IgE-binding epitopes (Ani s 1) and a binding motif of human leukocyte antigen (Ani s 2 and 9) demonstrated by previous studies were conserved. The similarities of the amino acid sequences of the allergens indicate possible similar allergy-associated health risks in humans infected with or accidentally ingesting either Anisakis species.

Experimental challenge of Anisakis simplex sensu stricto and Anisakis pegreffii (Nematoda: Anisakidae) in rainbow trout and olive flounder

The third-stage larvae of Anisakis simplex sensu lato (s.l.) are found in many marine fishes. To ensure food safety, it is important to determine whether these larvae are present in the body muscle of commercial fish species. However, there is little information regarding the tissue specificity of Anisakis and two of its sibling species, A. simplex sensu stricto (s.s.) and Anisakis pegreffii, that are common in marine fish in Japanese waters. We orally challenged rainbow trout ( Oncorhynchus mykiss (Walbaum)), and olive flounder ( Paralichthys olivaceus (Temminck and Schlegel)) with L3 larvae of these two sibling species and monitored infection for 5 weeks. In rainbow trout, A. simplex s.s., but not A. pegreffii larvae, migrated into the body muscle. A small number of freely moving A. pegreffii larvae were recovered within the body cavity. In olive flounder, A. simplex s.s. larvae were found in both the body cavity and body muscle. A. pegreffii larvae were found only in the body cavity and primarily encapsulated in lumps. Our results indicate that there are differences in the sites of infection and host specificity between the two sibling species of A. simplex s.l.

Anisakis simplex sensu lato associated with red vent syndrome in wild adult Atlantic salmon Salmo salar in England and Wales

Wild Atlantic salmon Salmo salar with swollen and/or bleeding vents (red vent syndrome) have been observed in rivers across England and Wales. Low numbers of salmon with this condition have previously been recorded, but reports have increased in 2006 and 2007. Affected and non-affected salmon were sampled from fish traps and their vent pathology was examined. Third stage larvae of the nematode Anisakis simplex sensu lato were observed in the tissue surrounding the vent in all affected fish. Histology of the vent showed gross lesions with an inflammatory response associated with non-encapsulated nematode worms in the connective tissue and skeletal muscle. The presence of the parasite in the unusual location of the vent areas, with associated haemorrhaging, is possibly a new emerging pathological association with the nematode A. simplex infection in Atlantic salmon. The reason for this unusual tissue tropism by larval A. simplex and the significance on already depleted salmon stocks are currently unknown.

Anisakis spp. in European hake, Merluccius merluccius (L.) from the Atlantic off north-west Africa and the Mediterranean off southern Spain

AbstractWe studied the parasitization by Anisakis spp. in European hake (Merluccius merluccius) of 40–52 cm from the Atlantic off north-west Africa and the Mediterranean off southern Spain. Infection parameters differed: The fish from the Atlantic showing a prevalence of 87.97% and a mean intensity of 4.69, while, in those from the Mediterranean, these were 41.27% and 1.73, respectively. In both samples the two-third larval stage types were isolated: Anisakis simplex sensu lato and Anisakis larvae type II, with prevalence of 85.71% and 30.83% in fish from the Atlantic and 41.27% and 1.59% for those from the Mediterranean, respectively. In both samples, the prevalence of larvae in viscera was clearly higher than in the muscle tissue. We also observed an increase in parasitization with increasing host length, those ≥ 46 cm having the highest prevalences (94.87% for those from the Atlantic and 58.33% for those from the Mediterranean; p<0.03).

Accumulation of heavy metals in the whaleworm Anisakis simplex s.l. (Nematoda: Anisakidae)

Third-stage larval and adult infrapopulations of the whaleworm Anisakis simplex sensu lato (s.l.) (Nematoda: Anisakidae) from their respective fish, cephalopod and cetacean hosts caught or stranded in the Galician coast (north-west Spain), were analysed for heavy metals by atomic absorption spectrometry. Results suggest that the whaleworm may accumulate lead and copper to levels far in excess of their host tissues.

Element concentration variability in the whaleworm Anisakis simplex s.l.

Concentrations of the elements C, N, Fe, Na, K, Ca and Mg were analysed by chromatography and atomic absorption spectrometry in the whaleworm Anisakis simplex sensu lato. Nearly all mean inorganic element concentrations measured were higher in adult worms than in larval forms. Similarly, adults contained significantly higher nitrogen (i.e. lower C/N ratio values) than either eggs or larvae. Evidence for the significance of the parasitic life cycle stage and the systematic position of their hosts on the element concentration variability is discussed.