Anisakis allergy: unjustified social alarm versus healthy diet; commentary to the "Letter to the Editor" of Drs Daschner, Levsen, Cipriani, and del Hoyo, referencing to "World-wide prevalence of Anisakis larvae in fish and its relationship to human allergic anisakiasis: a systematic review".

Anisakiasis is an underrecognized condition globally, and accurate diagnosis remains problematic even in countries where the condition is well known. Our "systematic review" was conducted according to Prisma guidelines. The stated basis of our study was "syndromic surveillance." Both methods are recognized in published literature as valid to identify or predict disease and to make accessible large amounts of evidence from published literature. Our study identified Anisakis allergy "hot spots" and other geographical areas where fish are highly infected with Anisakis without commensurate studies of human allergy. Results of our study will open up new lines of enquiry. Norway, used as an example to discredit the scientific integrity of our article, has a cuisine thriving with raw fish dishes and many sushi restaurants. The peer reviewed data sets, confirmed A. simplex sensitization among the Norwegian population, although this has been overlooked by the authors of the "Letter to the Editor." The identification of hot spots in our study may be influential in many ways not the least in raising diagnostic suspicion to expedite accurate diagnosis.

World-wide prevalence of Anisakis larvae in fish and its relationship to human allergic anisakiasis: a systematic review.

The infective stage of Anisakidae nematodes responsible for allergic reactions in humans is found in a variety of edible fish and cephalopods. The identification of geographical regions that are high risk for infected seafood may help prevent allergic reactions in humans. Despite an abundance of published literature which has identified anisakid larvae in an array of edible seafood as well as scattered reports of human allergic anisakiasis, the relationship between the two has not been fully explored. Therefore, a systematic spatio-temporal study was conducted to determine the prevalence of Anisakis spp. in fish from January 2000 to August 2020 firstly to explore the relationship between fish infection and cases of allergic anisakiasis and secondly to use fish infection data to map potential allergic anisakiasis 'hot spots'. A systematic literature search for original English text articles was conducted through search engines, Web of Science, Scopus, PubMed, Science Direct and Google Scholar. Out of 3228 articles which describe anisakid infection in fish, 264 were used for data extraction. Of 904 articles describing allergic anisakiasis, 37 were used for data extraction. A qualitative summary of the extracted data was performed using equal interval method (ArcMap software) in order to compare the global distribution of Anisakis-infected fish. Of the 152-identified fish hosts, five families were most commonly infected with Anisakis spp. These included Lophiidae (86.9%), Trichiuridae (77.05%), Zeidae (70.9%), Merlucciidae (67.8%) and Gadidae (56.8%). The hot spot areas for allergic anisakiasis were North and northeast of Atlantic Ocean, southwest of USA, west of Mexico, south of Chile, east of Argentina, Norway, UK and west of Iceland (confidence 99%). The highest rate of allergic anisakiasis was in Portugal and Norway with the prevalence rate of 18.45-22.50%. Allergologists should consider allergic anisakiasis as a public health issue particularly in high-risk countries where high prevalences in fish have been demonstrated.