Acute Small-Bowel Obstruction From Intestinal Anisakiasis After the Ingestion of Raw Clams; Documenting a New Method of Marine-to-Human Parasitic Transmission

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.

Anisakiasis of the Terminal Ileum Removed by Colonoscopy

A 35-year-old Japanese man with no significant medical history presented to the emergency department complaining of abdominal pain, nausea, and vomiting 35 h after ingesting raw horse mackerel, sardines, and tuna. Computed tomography of the abdomen with intravenous contrast revealed significant thickening of the terminal ileum with mild proximal dilatation and moderate ascites. On colonoscopy, an actively moving anisakis larva was discovered in the terminal ileum. The larva was removed with endoscopic forceps. The patient's symptoms resolved quickly following the procedure.

Genera and Species of the Anisakidae Family and Their Geographical Distribution

Simple Summary

The parasites of the Anisakidae family infest mainly marine mammals; however, they have the ability to infest paratenic hosts such as mollusks, small crustaceans and fish. The consumption of meat from animals of aquatic origin favors the acquisition of the disease known as Anisakiasis or Anisakidosis, depending on the species of the infecting parasite. Currently, the identification of the members of this family is carried out through the use of molecular tests, which brings about the generation of new information. The purpose of this review was to identify the genus and species of the Anisakidae family by reviewing scientific papers that used molecular tests to confirm the genus and species. The adaptability of the Anisakidae family to multiple hosts and environmental conditions allows it to have a worldwide distribution. As it is a zoonotic agent and causes non-specific clinical symptoms, it is important to know about the different members of the Anisakidae family, as well as the hosts where they have been collected.

Abstract

Nematodes of the Anisakidae family have the ability to infest a wide variety of aquatic hosts during the development of their larval stages, mainly marine mammals, aquatic birds, such as pelicans, and freshwater fish, such crucian carp, these being the hosts where the life cycle is completed. The participation of intermediate hosts such as cephalopods, shrimp, crustaceans and marine fish, is an important part of this cycle. Due to morphological changes and updates to the genetic information of the different members of the family, the purpose of this review was to carry out a bibliographic search of the genus and species of the Anisakidae family identified by molecular tests, as well as the geographical area in which they were collected. The Anisakidae family is made up of eight different parasitic genera and 46 different species. Those of clinical importance to human health are highlighted: Anisakis pegreffi, A. simplexsensu stricto, Contracaecumosculatum, Pseudoterranova azarazi, P. cattani, P. decipiens and P. krabbei. The geographical distribution of these genera and species is located mainly in the European continent, Asia and South America, as well as in North and Central America and Australia. Based on the information collected from the Anisakidae family, it was determined that the geographical distribution is affected by different environmental factors, the host and the ability of the parasite itself to adapt. Its ability to adapt to the human organism has led to it being considered as a zoonotic agent. The disease in humans manifests nonspecifically, however the consumption of raw or semi-raw seafood is crucial information to link the presentation of the parasite with the disease. The use of morphological and molecular tests is of utmost importance for the correct diagnosis of the genus and species of the Anisakidae family.

Intestinal anisakiasis with severe intestinal ischemia caused by extraluminal live larvae: a case report

Background

Anisakiasis is a parasitic infection caused by Anisakis worms found in raw fish. Most cases of anisakiasis occur in the stomach and rarely occur in the intestine. It is extremely rare for live larvae to break through the intestine into the mesentery and cause severe intestinal ischemia. Anisakiasis can be treated conservatively, because the larvae will die in approximately 1 week, but, sometimes, a serious condition can arise, as in this case. We report the first case of extraluminal anisakiasis in which a live Anisakis worm caused severe intestinal ischemia.

Case presentation

The patient was a 26-year-old woman who ate squid a week prior. She had abdominal pain and was admitted to our emergency department. On physical examination, abdominal guarding and rebound tenderness were present in her lower abdomen. Contrast-enhanced computed tomography showed ascites, the whirl sign, localized submucosal edema of the intestinal wall, and a dilated small bowel segment with edema. We suspected the strangulated small bowel obstruction based on the CT-scan findings. To rule out the strangulated small bowel obstruction, laparoscopic exploration was performed. Bloody ascites in the pouch of Douglas and severe inflammation in 20 cm of the ileum were observed. An Anisakis larva had perforated the intestinal wall and was found alive in the mesentery. The ileum had developed a high degree of ischemia, so the affected section was resected. Histopathological examination revealed that the Anisakis worm body was in the inflamed mesentery and caused a high degree of ischemia in the intestinal tract. The patient was discharged 9 days after surgery.

Conclusions

A living Anisakis larva punctured the mesentery of the small intestine, resulting in severe intestinal ischemia. As seen in this case, intestinal anisakiasis may cause serious symptoms, and a low threshold for performing diagnostic laparoscopy for the early diagnosis of bowel ischemia secondary to anisakiasis can be useful in determining the definite diagnosis and indications for resection.

Anisakiasis in a Canadian patient with incarcerated epigastric hernia

Anisakiasis is human zoonotic parasitic infection caused by a nematode parasite called Anisakis. This infection is usually reported in Asian countries where consumption of raw seafood is common. Very few cases have been reported in North America. We present the case of a female Canadian patient with an Anisakis larvae in an incarcerated ventral hernia. Cases of Anisakis infections are exceedingly rare in western countries, with very few previous reports describing extra-gastrointestinal cases. Diagnosis is often difficult since the symptoms of anisakiasis are not pathognomonic. As the larvae cannot survive in the body, conservative treatment might be effective in intestinal anisakiasis and surgery is usually performed when complications are encountered. Preventive measures are crucial and include educating the public about the risks of raw fish consumption and the importance of visually inspecting consumed fish and freezing it before ingestion to kill the larvae and prevent the infection.

Comparison of risk factors between human intestinal and gastric Anisakiasis

BACKGROUND

Little is known in the difference of host factors between intestinal and gastric anisakiasis. The aim of this study was to investigate the associated factors of intestinal anisakiasis in patient's characteristics and the subsequent variation compared to gastric anisakiasis.

METHODS

At St. Luke's International Hospital in Tokyo, Japan, a retrospective cohort study was conducted from April 2004 to June 2017. All adult patients who were clinically diagnosed as anisakiasis based on Computed Tomography (CT) scan or endoscopy were included, and anti-Anisakis antibodies (IgG and IgA) were measured for serological validation of anisakiasis, strengthen the diagnosis. Anisakiasis was categorized as either intestinal or gastric depending on its affected site. We compared patients' demographics, social history, and physical and laboratory findings between those with intestinal and gastric anisakiasis by bivariate analyses, followed by multivariate analyses.

RESULTS

A total of 302 patients were included in this study, where the mean age (SD) was 46.5 (14.4) and 66.6% were male. Ninety-two patients (30.5%) had intestinal anisakiasis. Multivariate regression revealed that patients with intestinal anisakiasis were more 45 years old or older (odds ratio (OR) 3.45, 95% confidence interval (CI): 1.53-7.69), male (OR 2.70, 95% CI: 1.20-6.25) and regular alcohol drinker. In terms of the physical and laboratory findings, patients with intestinal anisakiasis had greater heart rate (OR 2.86, 95% CI: 1.33-6.25), higher total protein (OR 2.86, 95% CI: 1.16-6.67), and higher C-reactive protein (CRP) (OR 11.1, 95% CI: 3.03-33.3).

CONCLUSIONS

Older males who were regular alcohol drinkers were associated with intestinal anisakiasis, and often heart rate, total protein, and CRP were elevated compared to those of patients with gastric anisakiasis.

Anisakiasis in the Small Intestine with Excessive Bleeding That Was Difficult to Diagnose Endoscopically

Anisakiasis involves the stomach in most cases and occurs rarely in the small intestine. Anisakiasis in the small intestine is associated with abdominal pain and obstruction and is rarely associated with intestinal bleeding. Unlike in the stomach, anisakiasis in the small intestine is difficult to diagnose anatomically. The patient in this case study developed hypovolemic shock due to excessive bleeding and underwent emergency surgery. With the recent increase in the consumption of raw fish around the world, this report provides an important finding of bleeding in the small intestine due to an unknown cause.

Functional insights into the infective larval stage of Anisakis simplex s.s., Anisakis pegreffii and their hybrids based on gene expression patterns

BACKGROUND

Anisakis simplex sensu stricto and Anisakis pegreffii are sibling species of nematodes parasitic on marine mammals. Zoonotic human infection with third stage infective larvae causes anisakiasis, a debilitating and potentially fatal disease. These 2 species show evidence of hybridisation in geographical areas where they are sympatric. How the species and their hybrids differ is still poorly understood.

RESULTS

Third stage larvae of Anisakis simplex s.s., Anisakis pegreffii and hybrids were sampled from Merluccius merluccius (Teleosti) hosts captured in waters of the FAO 27 geographical area. Specimens of each species and hybrids were distinguished with a diagnostic genetic marker (ITS). RNA was extracted from pools of 10 individuals of each taxon. Transcriptomes were generated using Illumina RNA-Seq, and assembled de novo. A joint assembly (here called merged transcriptome) of all 3 samples was also generated. The inferred transcript sets were functionally annotated and compared globally and also on subsets of secreted proteins and putative allergen families. While intermediary metabolism appeared to be typical for nematodes in the 3 evaluated taxa, their transcriptomes present strong levels of differential expression and enrichment, mainly of transcripts related to metabolic pathways and gene ontologies associated to energy metabolism and other pathways, with significant presence of excreted/secreted proteins, most of them allergens. The allergome of the 2 species and their hybrids has also been thoroughly studied; at least 74 different allergen families were identified in the transcriptomes.

CONCLUSIONS

A. simplex s.s., A. pegreffi and their hybrids differ in gene expression patterns in the L3 stage. Strong parent-of-origin effects were observed: A. pegreffi alleles dominate in the expression patterns of hybrids albeit the latter, and A. pegreffii also display significant differences indicating that hybrids are intermediate biological entities among their parental species, and thus of outstanding interest in the study of speciation in nematodes. Analyses of differential expression based on genes coding for secreted proteins suggests that co-infections presents different repertoires of released protein to the host environment. Both species and their hybrids, share more allergen genes than previously thought and are likely to induce overlapping disease responses.

Small bowel obstruction caused by Anisakis and Meckel's diverticulum: a rare case

INTRODUCTION

Anisakiasis is a parasitic infection caused by the ingestion of raw fish contaminated by larval nematodes of Anisakis species. Intestinal or extraintestinal manifestations are rated to > 4% and >1% respectively.

PRESENTATION OF CASE

A 61-year old patient was admitted to our General Surgical and Emergency Unit because of sudden abdominal pain, vomit and constipation. He had eaten raw fish 3 days before admission. Laboratory data showed high levels of WBC and PCR. CT scanning showed "dilation of jejunum and ileum loops, thickening of the terminal ileum and cecum and signs of inflammation of the intestinal wall and mesentery". The following emergency surgical procedure was performed: laparotomy with evidence of obstruction of the small bowels, a giant Meckel's diverticulum, resection of terminal ileum and cecum and ileocolonic anastomosis. At the microscopic examination, the intestinal wall appeared occupied by a transmural inflammatory infiltrate, mainly eosinophilic, edema and nematode larvae, referable to Anisakis, surrounded by necrotic-inflammatory material. Moreover, there was evidence of giant a Meckel's diverticulum.

DISCUSSION

Normally, enteric anisakiasis exhibits leukocytosis with eosinophilia and high CRP levels. There are cases of successful medical treatment and other cases of endoscopic treatment avoiding surgical procedure. In our case, enteric Anisakias had not been taken into consideration at the moment of the operation and only histopathology could reveal Anisakis larvae inside the intestinal wall.

CONCLUSION

Our surgical approach is considered in literature as the best one for this clinical presentation. Those patients need to be better studied and more attention should be paid to their history.

Anisakiasis Causing Acute Dysentery in Malaysia

Human anisakiasis is a zoonosis acquired by eating raw or undercooked infected seafood. Herein, we report a case of acute dysentery caused by anisakiasis in a 64-year-old man in Malaysia. A colonoscopy was performed and a nematode larva was found penetrating the mucosa of the ascending colon. Bleeding was observed at the site of penetration. Y-shaped lateral epidermal cords were seen from the cross section of the worm, which is a prominent feature of Anisakis larva. Molecular analysis using polymerase chain reaction of cytochrome oxidase 2 (cox2) gene confirmed the specimen to be larva of Anisakis simplex.

Principal component analysis of factors for sensitization to Anisakis spp. in postpartum women

Introduction

Immunoreactivity to Anisakis spp. is believed to be associated with frequency of fish intake. The objective of this study was to evaluate, using principal component analysis, the main factors potentially involved in reactivity to these nematodes in postpartum women.

Methods

Retrospective study conducted on a database of 309 postpartum women. All completed a structured questionnaire and had blood samples collected for ELISA analysis of specific immunoglobulins against total Anisakis spp. antigens and assessment of reactivity. Parametric and nonparametric tests were used to assess factors for sensitization in the reactive and nonreactive groups, and a principal component analysis was performed. A Pearson correlation matrix with varimax rotation was used to assess the variables of interest (place of residence, age, number of prenatal visits, type of birth facility, fish intake and frequency, raw fish intake, fish handling, history of allergies).

Results

After exclusions, samples from 203 women were assessed. Of these, 52 (25.6%) were reactive for anti-Anisakis IgG. Most women claimed not to handle fish (n = 121) and eat fish only sporadically (n = 71). Significant differences in age were seen between the reactive and nonreactive groups (p = 0.001). The first two components explained 32.55% and 38.94% of variances in the nonreactive and reactive groups respectively. The adjusted matrix assigned greater probabilistic weight to weekly intake frequency (0.804), followed by raw fish intake (0.759), with differences in relation to the nonreactive group.

Conclusion

Correlation matrices revealed a direct relationship between seroreactivity to Anisakis spp. and frequency of fish intake in a sample of postpartum women.