Anisakiasis is an emerging zoonosis caused by the fish parasitic nematode Anisakis. Spain appears to have the highest reported incidence in Europe and marinated anchovies are recognised as the main food vehicle. Using data on fishery landings, fish infection rates and consumption habits of the Spanish population from questionnaires, we developed a quantitative risk assessment (QRA) model for the anchovy value chain. Spaniards were estimated to consume on average 0.66 Anisakis per untreated (non-frozen) raw or marinated anchovy meal. A dose-response relationship was generated and the probability of anisakiasis was calculated to be 9.56 × 10−5 per meal, and the number of annual anisakiasis cases requiring medical attention was predicted between 7,700 and 8,320. Monte Carlo simulations estimated post-mortem migration of Anisakis from viscera to flesh increases the disease burden by >1000% whilst an education campaign to freeze anchovy before consumption may reduce cases by 80%. However, most of the questionnaire respondents who ate untreated meals knew how to prevent Anisakis infection. The QRA suggests that previously reported figures of 500 anisakiasis per year in Europe is a considerable underestimate. The QRA tool can be used by policy makers and informs industry, health professionals and consumers about this underdiagnosed zoonosis.
Harvesting and exploiting limited fisheries resources in a sustainable manner also implies achieving maximum added value from the raw material. However, the presence of parasites in the products may adversely affect consumer perception and/or pose a direct health hazard. As a major steppingstone of the PARASITE project, an epidemiological survey was carried out to provide the basis for analysis and prediction of consumer exposure risk due to the presence of anisakid nematodes in fish from European wild-catch fisheries. The project consisted of nine separate workpackages (WP) where the exposure risk assessment survey was organized within WP2. The surveillance task also provided the data or samples needed for data management and sample storage (WP3, Biobank), molecular and genetic parasite species identification (WP4), and statistical modelling and inference (WP8). In total 17,760 fish belonging to 16 teleost species were examined for anisakids, with special emphasis on economically and ecologically important species such as Atlantic mackerel, herring, European hake, Atlantic cod and anchovy. The target fish species were sampled at four major European fishing areas including the Barents Sea, North Sea, Baltic Sea, Grand Sole Bank, waters off NW Spain and Portugal, central and western parts of the Mediterranean Sea, and the Adriatic Sea. Thus, the survey represents the largest and most comprehensive epidemiological data compilation of anisakids ever generated in terms of geographical range as well as number of fish host species and sample size. An important requirement of the survey was the use of commonly accepted nematode detection methods, i.e. the UV-press method or artificial digestion, to quantify infection level and spatial distribution of anisakid larvae in the target fish species. The basic layout, setup and principles of the method, along with a discussion of possible source of errors are described. Additionally, the molecular and genetic markers which were used to identify and characterize different species and populations of anisakids from the targeted fish host species and geographical areas, are reviewed as well. Some basic parasite infection characteristics of each fish host species, and any relationships with the presumably most important infection predictors, i.e. fish host body size and fishing locality, are presented and discussed. Emphasis is put on anisakid occurrence in the flesh of the fish. Based on the findings, a graphical exposure risk profile is introduced, including fish species or products thereof, which due to common processing or preparation practices, are at highest risk to act as source of anisakiasis in Europe.
BackgroundIn countries with elevated prevalence of zoonotic anisakiasis and high awareness of this parasitosis, a considerable number of cases that associate Anisakis sp. (Nematoda, Anisakidae) and different bowel carcinomas have been described. Although neoplasia and embedded larvae were observed sharing the common site affected by chronic inflammation, no association between the nematode and malignancy were directly proved. Similarly, no data are available about the effect of secretory and excretory products of infecting larvae at the host’s cellular level, except in respect to allergenic interaction.MethodsTo test the mechanisms by which human non-immune cells respond to the larvae, we exposed the fibroblast cell line HS-68 to two Anisakis products (ES, excretory/secretory products; and EC, crude extract) and evaluated molecular markers related to stress response, oxidative stress, inflammation and apoptosis, such as p53, HSP70, TNF-α, c-jun and c-fos, employing cell viability assay, spectrophotometry, immunoblotting and qPCR.ResultsBoth Anisakis products led to increased production of reactive oxygen species (ROS), especially in EC-treated cells. While the ES treatment induces activation of kinases suggesting inflammation and cell proliferation (or inhibition of apoptosis), in EC-treated cells, other signaling pathways indicate the inhibition of apoptosis, marked by strong upregulation of Hsp70. Elevated induction of p53 in fibroblasts treated by both Anisakis products, suggests a significantly negative effect on the host DNA.ConclusionsThis study shows that in vitro cell response to Anisakis products can result in at least two different scenarios, which in both cases lead to inflammation and DNA damage. Although these preliminary results are far from proving a relationship between the parasite and cancer, they are the first to support the existence of conditions where such changes are feasible.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1895-5) contains supplementary material, which is available to authorized users.
Background: Anisakiasis is a zoonotic disease caused by accidental ingestion of live Anisakis spp. third-stage larvae present in raw or undercooked seafood. Symptoms of this emerging infectious disease include mild-to-severe abdominal pain, nausea, and diarrhea. Some patients experience significant allergic reactions.Aims: In order to better understand the onset of anisakiasis, we aimed to: (i) histopathologically describe severe inflammatory/hemorrhagic infection site lesions in Sprague-Dawley rats experimentally infected with Anisakis pegreffii larvae; and (ii) qualitatively and quantitatively characterize the transcriptomes of affected tissues using RNA-Seq.Methodology: The experiment was performed on 35 male rats, sacrificed at 5 time points (6, 10, 18, 24, and 32 h post-infection). Gastric intubation was performed with 10 A. pegreffii larvae (N = 5 infected rats per time point) or 1.5 ml of saline (external control N = 2 rats). 16 pools, seven for muscle tissues and nine for stomach tissues, were created to obtain robust samples for estimation of gene expression changes depicting common signatures of affected versus unaffected tissues. Illumina NextSeq 500 was used for paired-end sequencing, while edgeR was used for count data and differential expression analyses.Results: In total, there were 1372 (855 up and 517 down) differentially expressed (DE) genes in the Anisakis-infected rat stomach tissues, and 1633 (1230 up and 403 down) DE genes in the muscle tissues. Elicited strong local proinflammatory reaction seems to favor the activation of the interleukin 17 signaling pathway and the development of the T helper 17-type response. The number of DE ribosomal genes in the Anisakis-infected stomach tissue suggests that A. pegreffii larvae might induce ribosomal stress in the early infection stage. However, the downstream pathways and post-infection responses require further study. Histopathology revealed severe inflammatory/hemorrhagic lesions caused by Anisakis infection in the rat stomach and muscle tissues in the first 32 h. The lesion sites showed infiltration by polymorphonuclear leukocytes (predominantly neutrophils and occasional eosinophils), and to a lesser extent, macrophages.Conclusion: Understanding the cellular and molecular mechanisms underlying host responses to Anisakis infection is important to elucidate many aspects of the onset of anisakiasis, a disease of growing public health concern.
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