Genera and Species of the Anisakidae Family and Their Geographical Distribution

As the Worm Turns-A Rare Cause of Intestinal Obstruction

BACKGROUND

Anisakiasis, a zoonotic disease caused by the nematode Anisakis, poses a significant concern for public health, particularly in regions with high consumption of raw or undercooked fish.

CASE PRESENTATION

We present a case report of a 41-year-old woman who developed severe abdominal symptoms, ultimately diagnosed with intestinal obstruction due to Anisakis infestation, requiring surgery. Despite the absence of prominent eosinophilia or specific radiological findings, the diagnosis was confirmed through histological examination, highlighting the importance of considering anisakiasis in patients with a history of raw seafood consumption.

CONCLUSION

The case underscores the diagnostic challenges associated with anisakiasis, emphasizing the need for increased awareness among healthcare professionals and the public regarding the risks of consuming raw or undercooked seafood. Effective management requires a multidisciplinary approach, including clinical assessment, imaging studies, and histological evaluation, to ensure timely diagnosis and appropriate treatment.

Intussusception as a Presentation of Anisakis Infestation in the Global Era of Raw Fish Consumption: A Case Report and Literature Review

Anisakiosis, also known as Anisakis larvae infestation, is an increasing parasitic infestation due to the worldwide spread of raw fish and shellfish consumption habits. We present a rare presentation of intestinal intussusception as a preoperative diagnosis and noticed it postoperatively due to Anisakis larvae. A 43-year-old man presented to the emergency department with abdominal pain around the umbilicus and vomiting for several hours. On physical examination at presentation, he had tenderness in the lower abdomen. His radiological studies showed a right-sided pseudo-kidney sign and ileo-colonic intussusception on ultrasound echography. His computed tomography images added findings of submucosal edema and wall thickening in the terminal ileum, swollen regional lymph nodes, and ascites. An urgent laparotomy was performed for ileo-colonic intussusception of an unknown cause. During the laparotomy, the ileocecal intussusception was manually reduced after dissecting the adhesion due to the previous appendectomy, and a partial ileotomy was undertaken using the Endo-GIA automatic anastomosis device. At the resected ileal wall surface, the presence of Anisakis larvae was noticed, and anisakidosis was diagnosed. The dietary history taken post-operatively revealed that he had eaten salmon, bonito, and squid sashimi four days prior to his emergency department visit. His postoperative course was uneventful, and he was discharged from the hospital on the fifth day postoperatively. Anisakiosis must be in the differential diagnosis of intussusception, and eating history seems like a cue to diagnose, and it might be meaningful to clinicians.

Sample size planning and the statistical significance of official controls by sampling

Acceptance sampling is important for food safety and is a relevant tool at production and official control levels, as it helps decision-making processes and verifies quality and food safety management. Generally, sampling plans are hypothesis tests of products that have been submitted for official appraisal and subsequent acceptance or rejection. The sample size is related to the set level of risk, the acceptable precision, and the tolerable misstatement size; therefore, sample size determination has a crucial role in setting up the accepted level of non-compliance and level of error. Using a simple predictive model based on combinatorics, this study showcases how sample size management can change the probability of rejecting good lots and/or accepting bad lots when the acceptance number is 0 (c=0). We showed that when c=0, a very high level of significance of the test corresponds to the high probability of rejecting a lot with an acceptable prevalence of defective items (type II error). We produced tables about the minimum sample size at different significance levels, which can be useful in the field. A paradigmatic example of the role of sample size in the acceptance-sampling plan is represented by the visual inspection for the detection of Anisakid larvae in fishery products. This study investigated this aspect and mainly referred to studies on the prevalence of larvae in farmed fish. We showed that, for lots ≥1000 items, the sample size is not strictly related to the lot size, but to draw a consistent control plan and reduce the variability in the clinical judgment, control authorities require a standardized approach. Because of this, the results on the prevalence of Anisakid larvae in farmed fish, if only based on sampling control plans, do not support a negligible risk statement, despite the claims reported in the EFSA opinion and several other studies.

Enteroparasites from the American White Pelican (Pelecanus erythrorhynchos) in Toluca Valley, Mexico

We examined 82 fresh fecal samples from American White Pelican (Pelecanus erythrorhynchos) at San Pablo Autopan, Toluca Valley, central Mexico, December 2021 to April 2022. Eggs of Contracaecum spp. were observed in 100%, Capillaria spp. in two (2.5%), Strongyloides spp. in eight (9.7%), and coccidial oocysts in 12 (15%).

Advancing understanding of the taxonomy and diversity of the genus Contracaecum in the great white pelican (Pelecanus onocrotalus)

Despite the wide distribution and health importance of anisakids of the genus Contracaecum, epidemiological data on their occurrence in definitive bird hosts are scarce, particularly from certain parts of the world that represent important wintering sites or migration stopovers for different bird species. In the present study, Contracaecum spp. infecting six great white pelicans (Pelecanus onocrotalus) in Israel were identified using light and scanning electron microscopy and phylogenetic analyses of nuclear internal transcribed spacer (ITS) and mitochondrial cytochrome c oxidase II (cox2). A PCR-RFLP method was also developed and applied to screen large numbers of Contracaecum parasites. Most (415/455) worms recovered were C. micropapillatum, followed by C. gibsoni (31/455), C. quadripapillatum (8/455), and C. multipapillatum E (1/455). Contracaecum micropapillatum from Israel and C. bancrofti from Australia are distinguishable by cox2 but less well resolved with ITS sequences, and could not be distinguished morphologically. Worms with cox2 matching C. gibsoni had ITS matching specimens identified as C. multipapillatum A. To the authors' knowledge, this represents the first of such studies in Israel and provides useful data on the ecology and distribution of different Contracaecum species of health and economic interest.

Ecology and effects of metazoan parasites of fish in transitional waters

Given the abundance, heterogeneity and ubiquity of parasitic organisms, understanding how they influence biodiversity, evolution, health and ecosystem functionality is crucial, especially currently when anthropogenic pressures are altering host–parasite balances. This review describes the features, roles and impacts of metazoan parasites of fish occurring in transitional waters (TW). These aquatic ecosystems are highly productive and widespread around the globe and represent most favourable theatres for parasitism given the availability of hosts (invertebrates, fishes and birds) and an increased probability of parasite transmission, especially of those having complex life cycles. Fascinating examples of how parasitism can influence different hierarchical levels of biological systems, from host individuals and populations to entire aquatic communities, through effects on food webs come from this kind of ecosystem. Edible fish of commercial value found in TW can harbour some parasite species, significantly reducing host health, marketability and food safety, with possible economic and public health consequences. Many TW are historically exploited by humans as sources of relevant ecosystem services, including fisheries and aquaculture, and they are highly vulnerable ecosystems. Alteration of TW can be revealed through the study of parasite communities, contributing, as bioindicators, for assessing environmental changes, health and restoration. Fish parasites can provide much information about TW, but this potential appears to be not fully exploited. More studies are necessary to quantify the ecological, economic and medical impacts fish parasites can have on these important ecosystems.

Intraspecific Genetic Variation of Anisakis typica in Indian Mackerel Caught from the Gulf of Thailand, Samut Songkhram Province

Anisakis nematodes infecting Indian mackerel (Rastrelliger kanagurta) were initially discovered in Thailand in our preliminary investigation. Nevertheless, the species of Anisakis collected has not been determined nor has its genetic variation been researched. Thus, this study aimed to molecularly identify the species of Anisakis specimens using the internal transcribed spacer (ITS) region of ribosomal DNA sequences. In addition, the intraspecific genetic variation was also determined using mitochondrial cytochrome oxidase subunit II (COII) gene sequences. The phylogenetic relationships of the ITS region classified all samples into Anisakis typica; however, the genetic variation between them could not be distinguished. By contrast, the phylogenetic tree analysis of the COII region identified all samples as A. typica, with 17 different haplotypes by 66 polymorphic sites and five of the substitutions resulted in amino acid change. Additionally, the distribution pattern of the COII region can be separated into two groups between South America and Asian countries. All our haplotypes belong to Asian countries. Compared with the two genetic markers used in this investigation, COII appears to be a better candidate for studying genetic variation sensitive to environmental changes and intermediate or definitive host behavioral changes.

Checklist of nematodes parasitizing fish in the Brazilian Amazon

This study presents a list of parasitic fish nematodes from the Brazilian Amazon based on the previous Brazilian list including scientific assessments carried out between 2010 and 2021. A total of 16 families, 48 species and 28 undetermined species of nematodes associated with fish are included in the checklist, in addition to 93 host species and 15 geographical records.