Anisakiasis is a rare parasitic disease which occurs when the larvae of the nematode Anisakis are ingested by humans through raw or undercooked fish or squid [1] [2]. The larvae invade the gastrointestinal lining leading to the symptoms of anisakiasis. The highest incidence of the illness has been reported to be in winter [3] due to the high consumption of raw fish in that season. The symptoms depend on the site invaded by the larvae and can be classified as gastric, intestinal, and ectopic anisakiasis [1] [4] [5]. A majority of the patients have gastric anisakiasis.

Symptoms of gastric anisakiasis typically start within 12 hours of ingestion of infected raw fish or squid [3] while those of intestinal anisakiasis have been reported to occur up to a week after ingestion [1] [6]. The commonest symptom is sudden onset severe abdominal or epigastric pain resembling an acute abdomen. This is accompanied by nausea and vomiting. Intestinal anisakiasis can present with symptoms resembling Crohn's disease with an inflammatory mass. Other reported presentations include severe hematemesis in patients with gastric ulcer and hemoptysis [3] [7] [8] [9] [10]. The Anisakis larvae do not survive for long in the human gastrointestinal tract and therefore the symptoms subside in a couple of weeks with medical management [11]. However, a few cases of intestinal strangulation and obstruction requiring surgical intervention have been reported [12] [13].

• Fever

  The warning from doctors came after they provided treatment to a 32-year old healthy man who had severe epigastric pain (pain in the upper abdomen), vomiting, and fever for a week. [news-medical.net]

  Gastroenterology, Hospital da Luz, Lisboa, Portugal Correspondence to Dr Joana Carmo, joanavcarmo{at}gmail.com Statistics from Altmetric.com Description A previously healthy man, aged 32 years, was admitted with severe epigastric pain, vomiting and low-grade fever [casereports.bmj.com]

  He complained of severe upper gut pain, and also vomited and had a fever. He didn’t go to the hospital until a week after the symptoms started. Carmo and her co-authors said that there was tenderness in the abdomen of the patient. [pulseheadlines.com]

  A 22-years-old man living in Hyuga City, Miyazaki Prefecture, Japan, developed high fever, respiratory distress, and pleural effusion after consumption of raw fish. [ncbi.nlm.nih.gov]

  Symptoms of anisakiasis include nausea, vomiting, abdominal distention and pain, diarrhea, blood and/or mucus in the stool, and fever. Allergic reactions can also occur. [medicinenet.com]

• Chest Discomfort

  Acute gastric anisakiasis with severe chest discomfort is rarely reported in Italy. [ncbi.nlm.nih.gov]

  Gastric irritation, such as peptic ulcer disease, may be included in the causes of chest pain or discomfort, but gastric anisakiasis presenting with chest pain has been reported in only a few cases to our knowledge. [oatext.com]

• Splenectomy

  Surgical treatment was performed successfully and consisted of excision of the gastric lesion and splenectomy. [ncbi.nlm.nih.gov]

• Localized Edema

  Ido et al. [ 8 ], in a study conducted in 12 patients, confirmed three common findings on AUS in patients with anisakiasis: (1) presence of a relatively large amount of ascitic fluid; (2) dilatation of the small intestine; and (3) marked localized edema [hindawi.com]

• Vomiting

  If misdiagnosed, it can become chronic, with intermittent abdominal pain, nausea and vomiting lasting from weeks to several years. [orpha.net]

  Symptoms include acute epigastric pain, nausea, and vomiting. A low-grade temperature is often associated. Acute symptoms typically resolve within a few days. However, presenting symptoms may persist subclinically on occasion for weeks and months. [ofid.oxfordjournals.org]

• Abdominal Pain

  The 1st patient was a 48-year-old female presenting with abdominal pain. An abdominal computed tomography scan showed a dilated small intestine and accumulation of ascites. [ncbi.nlm.nih.gov]

  The patient reported his pain as initially focused in the epigastric region then progressing to diffuse abdominal pain. [ofid.oxfordjournals.org]

• Nausea

  vomiting Raw fish 2 days AXR 3 days Ex lap, appendectomy Terminal ileum NA/Yes Yes Kang (2010) 60/F Abdominal pain, nausea, fever Raw fish 1 day AXR, CT 1 day Ex lap, SBR Jejunum NA/Yes Yes Masui (2006) 51/F Abdominal pain, nausea, vomiting Raw fish [ofid.oxfordjournals.org]

  If misdiagnosed, it can become chronic, with intermittent abdominal pain, nausea and vomiting lasting from weeks to several years. [orpha.net]

• Acute Abdomen

  We suggest that anisakiasis should be considered in the differential diagnosis of patients with acute abdomen. [ncbi.nlm.nih.gov]

• Diarrhea

  The chronic intestinal symptoms include weight loss, mild cramping, abdominal pain, and diarrhea, lasting for months or years. [orpha.net]

  A 69-year-old man was admitted for abdominal pain, diarrhea, and urticaria. Right hemicolectomy was performed because of an obstruction of the ascending colon and a palpable tumor of the right lower abdomen. [ncbi.nlm.nih.gov]

• Urticaria

  Infection with Anisakis causes a wide spectrum of clinical manifestations, ranging from symptoms related to the upper and occasionally lower digestive tract to allergic manifestations, mainly urticaria and anaphylaxis. [ncbi.nlm.nih.gov]

  In some cases anisakiasis is accompanied by an allergic response, such as urticaria, angioedema and anaphylactic shock. [orpha.net]

• Forgetful

  The first step in the diagnosis is to obtain a history of ingestion of raw or undercooked fish or squid, if possible, as patients may forget details about their meals. [symptoma.com]

  Rev Esp Enferm Dig 104: 607-610. [ Crossref ] Zullo A, Hassan C, Scaccianoce G, Lorenzetti R, Campo SM, et al. (2010) Gastric anisakiasis: do not forget the clinical history! [oatext.com]

• Neglect

  Akbar A, Ghosh S: Anisakiasis – a neglected diagnosis in the West. Dig Liver Dis 2005;37: 7–9. Ishida M, Harada A, Egawa S, Watabe S, Ebina N, Unno M: Three successive cases of intestinal anisakiasis. Dig Surg 2007;24: 228–231. [karger.com]

Clinical suspicion is very vital in the work up for anisakiasis. The first step in the diagnosis is to obtain a history of ingestion of raw or undercooked fish or squid, if possible, as patients may forget details about their meals. After a thorough physical examination, the next step is to order routine laboratory tests like complete blood count, erythrocyte sedimentation rate, serum electrolytes and stool test for larvae, although stool test is not useful in most cases.

Currently, upper gastrointestinal endoscopy forms the mainstay of the diagnosis and requires accurate interpretation of the clinical images to identify the causative worm sticking to the stomach wall. Intestinal anisakiasis is difficult to diagnose as the small intestine cannot be accessed with the endoscope [14]. Capsule endoscopy or double balloon endoscopy may not be available universally. Another method to diagnose anisakiasis is by examining Anisakis-specific immunoglobulin (Ig) A, IgG, and IgE. These tests have a high sensitivity [15] [16] but do not provide results immediately and are therefore not useful in practice.

Radiological tests can help to confirm the diagnosis of anisakiasis. On ultrasonography, features of anisakiasis include severe localized Kerckring’s fold edema (corn sign), and dilatation of the proximal small intestine with the accumulation of fluid [14]. Computed tomography scan findings show partial small bowel edema and dilatation of the small intestine with fluid collection on the cranial side of the lesion [12] [17] [18].

• Pneumoperitoneum

  In the plain abdominal radiograph, pneumoperitoneum was evident; a computed tomography (CT) scan of the abdomen confirmed the presence of extraluminal air. Anamnesis disclosed the ingestion of raw fish during the week preceding her illness. [ncbi.nlm.nih.gov]

• Gastric Lesion

  A small gastric perforation and a nodular area at the superior pole of the spleen were found. Surgical treatment was performed successfully and consisted of excision of the gastric lesion and splenectomy. [ncbi.nlm.nih.gov]

• Colitis

  Untreated anisakiasis may cause persistent inflammatory responses targeting remains of the larvae and can produce symptoms consistent with colitis, appendicitis, cholecystitis, or dyspepsia (12). [antimicrobe.org]

The clinical suspicion with a correct diagnosis of anisakiasis allows the establishment of a correct treatment; in most cases, the resolution is possible with conservative treatment, avoiding unnecessary surgery to the preoperative differential diagnosis [ncbi.nlm.nih.gov]

We describe 3 patients with small bowel obstruction who received empirical treatment with albendazole in which intestinal resection was not necessary. [doi.org]

The most effective treatment for intestinal anisakiasis has not yet been established. [karger.com]

Symptoms improved with conservative treatment, fasting, and transfusion. [hindawi.com]

One challenging issue in the diagnosis of anisakiasis is the molecular detection of the etiological agent even at very low quantity, such as in gastric or intestinal biopsy and granulomas. [ncbi.nlm.nih.gov]

Etiology Anisakiasis is caused by the ingestion of third stage larvae of Anisakid nematodes of the genus Anisakis, present in viscera or muscle of fish or cephalopods which are eaten raw, insufficiently cooked, smoked or marinated. [orpha.net]

Epidemiological data and clinical features were analysed. Particular attention was paid to the source of infection. In total, 73 cases were included in the analysis, while 34 were excluded. [ncbi.nlm.nih.gov]

Conclusion The present study is the first attempt to a better understanding of the epidemiological picture of anisakiasis in Italy, mining official data. [journals.plos.org]

Copyright information: 2008 the BMJ Publishing Group Linked Articles In this issue Journal of Epidemiology & Community Health 2008; 62 569-569 Published Online First: 16 Jun 2008. [jech.bmj.com]

Summary Epidemiology To date, more than 20,000 cases of anisakiasis have been reported worldwide, over 90% from Japan (2,000-3,000 cases reported annually), and the rest from the five continents: Asia (Korea), Europe (the Netherlands, Germany, France, [orpha.net]

Early diagnosis is very important as it could prevent unnecessary surgical procedures since the symptoms of intestinal anisakiasis may mimic other illnesses such as appendicitis, ileitis or peritonitis. [ncbi.nlm.nih.gov]

They're not cooking the fish so that is the only prevention method, keeping it cold," he said. [cbsnews.com]

Anisakiasis can be prevented with the following measures: Abstaining from eating raw fish or squid Adequately cooking or freezing fish before consumption (however, this does not necessarily prevent an allergic response): Proper cooking procedure recommends [dovemed.com]

Proper freezing conditions are key to preventing anisakiasis in sushi. [merckmanuals.com]

1. Chai JY, Darwin Murrell K, Lymbery AJ. Fish-borne parasitic zoonoses: status and issues. Int J Parasitol. 2005;35:1233–1254.
2. Sohn WM, Murrell JY. Anisakiosis (Anisakidosis) In: Palmer SR, Soulsby L, Torgerson PR, Brown DWG, editors. Oxford Textbook of Zoonoses-Biology, Clinical Practice, and Public Health Control. London, UK: Oxford University Press; 2011; pp. 774–786.
3. Sohn WM, Na BK, Kim TH, Park TJ. Anisakiasis: report of 15 gastric cases caused by Anisakis Type I larvae and a brief review of Korean Anisakiasis cases. Korean J Parasitol. 2015 Aug; 53 (4): 465 -470
4. Nawa Y, Hatz C, Blum J. Sushi delights and parasites: the risk of fishborne and foodborne parasitic zoonoses in Asia. Clin Infect Dis. 2005;41:1297–1303.
5. Audicana MT, Kennedy MW. Anisakis simplex: from obscure infectious worm to inducer of immune hypersensitivity. Clin Microbiol Rev. 2008;21:360–379
6. Shirahama M, Koga T, Ishibashi H, Uchida S, Ohta Y, Shimoda Y. Intestinal anisakiasis: US in diagnosis. Radiology. 1992;185:789–793.
7. Lee EJ, Kim YC, Jeong HG, Lee OJ. The mucosal changes and influencing factors in upper gastrointestinal anisakiasis: analysis of 141 cases. Korean J Gastroenterol. 2009;53(2):90–97.
8. Lee SH, Sin HG, Seol SY, Chung JM. A case of gastric anisakiasis causing severe gastric ulcer bleeding. Korean J Gastrointest Endosc. 1993;13:693–696.
9. Lee HS, Park KS, Jung KT, et al. A case of chronic gastric anisakiasis with massive bleeding. Korean J Gastrointest Endosc. 1993;13:697–700.
10. Kang DB, Park WC, Lee JK. Chronic gastric anisakiasis provoking a bleeding gastric ulcer. Ann Surg Treat Res. 2014;86:270–273.
11. Matsui T, Iida M, Murakami M, et al. Intestinal anisakiasis: clinical and radiologic features. Radiology. 1985;157:299–302.
12. Matsuo S, Azuma T, Susumu S, et al. Small bowel anisakiosis: a report of two cases. World J Gastroenterol. 2006;12:4106–4108
13. Takabe K, Ohki S, Kunihiro O, et al. Anisakidosis: a cause of intestinal obstruction from eating sushi. Am J Gastroenterol. 1998;93:1172–1173.
14. Shrestha S, Kisino A, Watanabe M, et al. Intestinal anisakiasis treated successfully with conservative therapy: importance of clinical diagnosis. Worl J Gastroenterol. 2014 Jan; 20 (2): 598 -602
15. Suzuki T, Ishida K, Ishigaoka S, et al. Studies on the immunological diagnosis of Anisakiasis. Kiseichusi. 1975;24:184–191.
16. Nisino C, Hayasaka H. Epidemiological Studies on Anisakiasis. Sapporoisi. 1977;46:73–88.
17. Yoon SW, Yu JS, Park MS, et al. CT findings of surgically verified acute invasive small bowel anisakiasis resulting in small bowel obstruction. Yonsei Med J. 2004;45:739–742.
18. Watanabe T, Ohta S, Iwamoto S, et al. Small bowel anisakiasis with self-limiting clinical course. Intern Med. 2008;47:2191–2192.