α-Gal specific-IgE prevalence and levels in Ecuador and Kenya: Relation to diet, parasites, and IgG4.

BACKGROUND: IgE to α-Gal is a cause of mammalian meat allergy and has been linked to tick bites in North America, Australia, and Eurasia. Reports from the developing world indicate that α-Gal sensitization is prevalent but has been little investigated. OBJECTIVE: We sought evidence for the cause(s) of α-Gal sensitization and lack of reported meat allergy among children in less developed settings in Ecuador and Kenya. METHODS: IgE to α-Gal and total IgE were assessed in children from Ecuador (n = 599) and Kenya (n = 254) and compared with children with (n = 42) and without known (n = 63) mammalian meat allergy from the southeastern United States. Information on diet, potential risk factors, and helminth infections was available for children from Ecuador. IgG4 to α-Gal and antibodies to regionally representative parasites were assessed in a subset of children. RESULTS: In Ecuador (32%) and Kenya (54%), α-Gal specific IgE was prevalent, but levels were lower than in children with meat allergy from the United States. Sensitization was associated with rural living, antibody markers of Ascaris exposure, and total IgE, but not active infections with Ascaris or Trichuris species. In Ecuador, 87.5% reported consuming beef at least once per week, including 83.9% of those who had α-Gal specific IgE. Levels of α-Gal specific IgG4 were not high in Ecuador, but were greater than in children from the United States. CONCLUSIONS: These results suggest that in areas of the developing world with endemic parasitism, α-Gal sensitization is (1) common, (2) associated with Ascaris exposure, and (3) distinguished by a low percentage of specific/total IgE compared with individuals with meat allergy in the United States.

Tick exposures and alpha-gal syndrome: A systematic review of the evidence.

Alpha-gal syndrome (AGS) refers to a delayed allergic reaction to galactose-α-1,3-galactose (α-Gal) that occurs following the consumption of mammalian meat or exposure to other animal-based foods and products. Increasing evidence suggests that bites from certain tick species can lead to AGS through sensitization of a person's α-Gal specific IgE levels. This systematic review aimed to summarize the published evidence on this topic to understand post-tick exposure AGS epidemiology and health outcomes. A structured search for literature in eight bibliographic databases was conducted in January, 2020. Grey literature and verification searches were also performed. The exposure of interest was tick bites, and the outcome of interest was AGS. All primary research study designs were eligible for inclusion. References were screened for relevance, and data extraction and risk-of-bias assessment were conducted on relevant studies by two independent reviewers. Data were descriptively and narratively summarized. Of 1390 references screened, 102 relevant articles (103 unique studies) were identified (published from 2009 to 2020). Most studies (76.7 %) were case report or series. These 79 studies reported on 236 post-tick exposure AGS cases from 20 different countries, mostly the United States (33.5 %), Spain (19.5 %), Sweden (18.6 %), and France (12.7 %). The mean case age was 51.3 (SD = 16.7, range 5-85, n = 229), while 68.1 % were male (n = 226). The most commonly reported symptom was urticaria (71.2 %); 51.7 % of cases reported anaphylaxis. Twenty-one observational studies were reported, mostly (95.2 %) among clinical allergy patients. The proportion of AGS cases that recalled tick bites was highly variable across these studies. Three challenge studies evaluating tick exposures and α-Gal levels in α-Gal deficient mice were identified. The existing evidence suggests tick bites lead to α-Gal-specific IgE sensitization, which can cause AGS, but further research is needed to clarify if AGS is only attributable to certain tick species and whether other vectors may trigger AGS. Additional research is needed on risk factors for AGS development, evaluation of diagnostic immunoassays, and the epidemiology and distribution of AGS in different populations. Climate change will likely lead to future cases of AGS in new regions worldwide due to the predicted alteration of suitable tick habitats.

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.

Anisakis spp. as etiological agent of zoonotic disease and allergy in European region ­ an overview

Nematodes of the genus Anisakis are worldwide distributed marine species parasitized many fish and cephalopod species as larvae and sea mammals as adult form. Anisakiosis as food-borne disease is an important public health problem worldwide. Human become infected by eating raw or undercooked fish or squids. Well documented are gastrointestinal response to infection but increasingly allergic symptoms were observed also after eating well cooked fish. This is because some of allergens of Anisakis are thermostable and resistant to pepsin treatment. Due to a significant increase in human mobility and global transport of fresh products like fish on ice, food-borne diseases require educational campaigns that pay attention to threats in various parts of the world.

Tick-induced allergies: mammalian meat allergy and tick anaphylaxis.

Mammalian meat allergy after tick bites and tick anaphylaxis are the most serious tick-induced allergies. They are often severe, should be largely avoidable and offer fascinating insights into the development and prevention of allergies. Australian clinicians reported the first cases of tick anaphylaxis and discovered the association between tick bites and the development of mammalian meat allergy. The subsequent finding of the allergen epitope within the meat responsible for the allergic reaction, α-gal (galactose-α-1,3-galactose), stimulated further interest in this emergent allergy. Reports of mammalian meat allergy associated with bites from several tick species have now come from every continent where humans are bitten by ticks. The number of diagnosed patients has continued to rise. Clinically, mammalian meat allergy and tick anaphylaxis present quite differently. The prominent role of cofactors in triggering episodes of mammalian meat allergy can make its diagnosis difficult. Management of mammalian meat allergy is complicated by the manifold potential therapeutic implications due to the widespread distribution of the mammalian meat allergen, α-gal. Exposures to α-gal-containing medications have proved lethal in a minority of people, and fatal tick anaphylaxis has been reported in Australia. Prevention of tick bites is prudent and practicable; killing the tick in situ is crucial to both primary and secondary prevention of allergic reactions. Mechanisms in the development of mammalian meat allergy constitute a paradigm for how allergies might arise.

A Kudoa septempunctata antigen induces production of IgE in BALB/c mice.

Kudoa septempunctata, a myxosporean parasite, is the causative agent of a foodborne illness associated with consumption of raw Paralichthys olivaceus (olive flounder). Because the lag phase of this illness is short (from 1 to 12 h), it is possible that an allergic response is relevant to this illness. To test whether a K. septempunctata antigen is the possible allergen, we injected a myxospore extract into BALB/c mice and measured IgE levels in serum. When the mice were injected with the myxospore extract, the total serum IgE concentration increased significantly after the second immunization as compared to the negative control. After the third immunization, total IgE concentration in the immunized mice reached 26.5 ng/ml and was almost equivalent to that of egg albumin-injected mice. Western blot analysis revealed that IgE antibodies-in serum samples that were collected from myxospore extract-injected mice-bound to at least two Kudoa proteins with molecular weight between 28 and 36 kDa. These results suggested that a K. septempunctata antigen is the allergen. Further studies are needed to clarify the contribution of allergy to the foodborne illness caused by K. septempunctata.

IgE, IgG1 and IgG4 response to specific allergens in sensitized subjects showing different clinical reactivity to Anisakis simplex.

SUMMARY: Background. Anisakis simplex hypersensitive subjects may be sensitized without clinical allergy, or experience acute symptoms or chronic urticaria induced by raw fish. We studied whether the 3 subgroups differ in IgE, IgG1 or IgG4 reactivity to specific Anisakis simplex allergens. Methods. 28 Anisakis simplex-hypersensitive adults, 11 with acute symptoms, 9 with chronic urticaria, and 8 sensitized were studied. IgE, IgG1 and IgG4 to rAni s 1, 5, 9 and 10 were sought by ELISA. IgE and IgG4 to nAni s 4 were determined by WB. Results. IgE to Ani s 1, 4, 5, 9, and 10 were found in 8, 3, 2, 5, and 9 sera, respectively. Nine sera did not react to any allergen. IgG1 to Ani s 1, 5, 9, and 10 were detected in 5, 16, 14, and 4 sera, respectively. Four sera did not react to any of the 4 allergens. IgG4 to Ani s 1, 4, 5, 9, and 10 were detected in 10, 0, 2, 6 and 1 sera, respectively. Fifteen subjects did not react to any of the 5 allergens. On ELISA sensitized subjects showed lower IgE and IgG1 levels than patients. IgG4 levels were highest in the sensitized group. The prevalence of IgE, IgG1 or IgG4 reactivity to any of the studied allergens did not differ between the 3 subgroups. Conclusion. The clinical expression of Anisakis simplex sensitization does not seem to depend on IgE reactivity to a specific allergen of the parasite, nor on the presence of IgG antibodies possibly related with blocking activity.

Changes over Time in IgE Sensitization to Allergens of the Fish Parasite Anisakis spp.

BACKGROUND: Sensitization to Anisakis spp. can produce allergic reactions after eating raw or undercooked parasitized fish. Specific IgE is detected long after the onset of symptoms, but the changes in specific IgE levels over a long follow-up period are unknown; furthermore, the influence of Anisakis spp. allergen exposure through consumption of fishery products is also unknown. OBJECTIVE: To analyse the changes in IgE sensitization to Anisakis spp. allergens over several years of follow-up and the influence of the consumption of fishery products in IgE sensitization. METHODS: Total IgE, Anisakis spp.-specific IgE, anti-Ani s 1 and anti-Ani s 4 IgE were repeatedly measured over a median follow-up duration of 49 months in 17 sensitized patients. RESULTS: Anisakis spp.-specific IgE was detected in 16/17 patients throughout the follow-up period. The comparison between baseline and last visit measurements showed significant decreases in both total IgE and specific IgE. The specific IgE values had an exponential or polynomial decay trend in 13/17 patients. In 4/17 patients, an increase in specific IgE level with the introduction of fish to the diet was observed. Three patients reported symptoms after eating aquaculture or previously frozen fish, and in two of those patients, symptom presentation was coincident with an increase in specific IgE level. CONCLUSIONS: IgE sensitization to Anisakis spp. allergens lasts for many years since specific IgE was detectable in some patients after more than 8 years from the allergic episode. Specific IgE monitoring showed that specific IgE titres increase in some allergic patients and that allergen contamination of fishery products can account for the observed increase in Anisakis spp.-specific IgE level. CLINICAL RELEVANCE: Following sensitization to Anisakis spp. allergens, the absence of additional exposure to those allergens does not result in the loss of IgE sensitization. Exposure to Anisakis spp. allergens in fishery products can increase the specific IgE level in some sensitized patients.

[Food sensitization in children with Opisthorchis felineus invasion].

AIM: To determine the mechanism of food sensitization in children with chronic Opisthorchis felineus invasion. PATIENTS AND METHODS: During the epidemiological study the groups of patients (7-10 years) with chronic opisthorchiasis (n = 237) and children without chronic opisthorchiasis (n = 496) were formed. The investigation included interviewing of parents/guardians, measurement of total IgE, specific IgE to food allergens and component-resolved diagnostic, real-time PCR in stool samples. RESULTS: The chronic opisthorchiasis invasion in children is associated with reduced risk of food sensitization, compared with non-infected group (9.7 vs 16.94%, OR = 0.53; 95% CI 0.31-0.88; p = 0.01). Opisthorchiasis of high intensity negatively correlated with increased level of specific IgE to food allergens in serum (OR = 0.46; 95% CI 0.24-0.91; p = 0.023). The association between level of total IgE and intensity of opisthorchiasis combinated with food sensitization was found. The sensitization to allergens class I (cyp c1, cor a11, gal d2, pru p3) is more prevalent in patients with opisthorchiasis, in uninfected children the sensitization to bet v1-homologues (mal d1, pru p1, cor a1, ara h8) is most common. CONCLUSIONS: The epidemiological data on the effect of the Opisthorchis felineus invasion on mechanisms of food sensitization in children were obtained.

[Two cases of allergies due to Anisakis simplex, positive to specific IgE for Ani s 12 allergen].

We report 2 cases of immediate allergies to Anisakis after ingestion of seafood. In case 1, after ingestion of flatfish, sea bream and mackerel, wheals and dyspnea occurred. Result of ImmunoCAP was class 5 for Anisakis. ELISA for specific IgE showed that the patient serum strongly reacted to Ani s 12. In case 2, after ingestion of flatfish and yellowtail, pruritus and dyspnea occurred. Result of ImmunoCAP was class 6 for Anisakis. ELISA for specific IgE showed that the patient serum reacted to Ani s 1, 4, 6 and 12. In both cases, skin prick tests were negative for suspected seafoods. These data suggests the possibility Ani s 12 is a major allergen of Anisakis allergy besides Ani s 1, 2 and 7. Ani s 12 is an allergen that was first reported in 2011. The reactivity of Ani s 12 specific IgE with ELISA may become useful for the diagnosis of Anisakis allergy.

IgE sensitization to the fish parasite Anisakis simplex in a Norwegian population: a pilot study.

The reports on fish parasite Anisakis simplex allergy have increased in countries with high fish consumption in the last decade. In Norway, a high consumption country, the prevalence of immunoglobulin E (IgE) sensitization to A. simplex was still unknown. Thus, our objective was to investigate the sensitization prevalence in this country. At the Haukeland University Hospital, Bergen, Norway, two main groups of surplus serum samples were collected: one from newly recruited blood donors (BDO) and the other from the Allergy laboratory (ALL) after analysing IgE and IgE antibodies. The latter was divided into three series: one containing unsorted sera and two sorted by either Phadiatop(®) ≥0.35 kU(A)/l or total IgE ≥1000 kU/l. The sera were analysed for total IgE and IgE antibodies against A. simplex, shrimp, house dust mite (HDM), cod and cross-reactive carbohydrates (CCDs). The prevalence of IgE sensitization to A. simplex was 2.0%, 2.2% and 6.6% in BDO, the unsorted and Phadiatop(®) positive serum groups, respectively. A considerable degree of cross-sensitization to shrimp and HDM is further suggested. Unspecific binding because of high total IgE or by binding to CCDs seemed to play a minor role. The prevalence of IgE sensitization to A. simplex appears to be lower in a Norwegian population than in other high fish-consuming countries, but might still be overestimated owing to cross-sensitization.

The Anisakis allergy debate: does an evolutionary approach help?

Allergic phenomena share common pathways with the immune response against helminth parasites. The definitions regarding allergens and their related concepts have their roots in the area of allergy research. The experience with the fish parasite Anisakis simplex-associated allergic features still nurtures an open debate on the necessity of larvae being alive to induce allergic reactions such as urticaria or anaphylaxis. Conceptual definitions of allergen, major allergen, as well as putatively crossreacting antibodies, as are used in food allergy, depend on the clinical relevance of specific IgE and deserve careful interpretation in the various forms of A. simplex-associated allergic features. Conversely, an evolutionary based interpretation of the presence of specific IgE depends on the viability of A. simplex.

Quantification of Anisakis simplex allergens in fresh, long-term frozen, and cooked fish muscle.

Fish-borne parasitic zoonoses such as Anisakiasis were once limited to people living in countries where raw or undercooked fish is traditionally consumed. Nowadays, several factors, such as the growing international markets, the improved transportation systems, the population movements, and the expansion of ethnic ways of cooking in developed countries, have increased the population exposed to these parasites. Improved diagnosis technology and a better knowledge of the symptoms by clinicians have increased the Anisakiasis cases worldwide. Dietary recommendations to Anisakis-sensitized patients include the consumption of frozen or well-cooked fish, but these probably do not defend sensitized patients from allergen exposure. The aim of our work was to develop a sensitive and specific method to detect and quantify Anisakis simplex allergens in fish muscle and its derivatives. Protein extraction was made in saline buffer followed by preparation under acid conditions. A. simplex antigens were detected by IgG immunoblot and quantified by dot blot. The allergenic properties of the extracts were assessed by IgE immunoblotting and basophil activation test. We were able to detect less than 1 ppm of A. simplex antigens, among them the allergen Ani s 4, in fish muscle with no cross-reactions and with a recovery rate of 82.5%. A. simplex antigens were detected in hakes and anchovies but not in sardines, red mullets, or shellfish. We detected A. simplex allergens in cooked hakes and also in hake stock. We proved that A. simplex allergens are preserved in long-term frozen storage (-20 degrees C +/- 2 degrees C for 11 months) of parasitized hakes. Basophil activation tests have proven the capability of the A. simplex-positive fish extracts to induce allergic symptoms.

Comparison of fecal microflora in children with atopic eczema/dermatitis syndrome according to IgE sensitization to food.

Atopic eczema/dermatitis syndrome (AEDS) commonly often arises during early infancy. In several intervention studies a beneficial influence on AEDS course of certain intestinal bacteria, administered as 'probiotics', has been described. To evaluate the possible role of the natural intestinal microflora in children with allergic eczema/dermatitis syndrome regarding immediate type hypersensitivity to food allergens, children with food allergy (AAEDS, n = 68) have been compared with children without detectable food allergy (NAEDS, n = 25). All children (n = 93) in preschool age, mean age of 2.6 (+/-1.8) years, diagnosed with AEDS who were treated as inpatients in 2003 in a dermatological hospital were included. The correlation between fecal microflora, parasites and specific immunoglobulin E (IgE) antibodies against common food allergens was analyzed. A similar composition of intestinal microflora in children with AAEDS and NAAEDS was found. The food allergens that were most frequently detected were egg white, cow milk, casein, peanut and hazelnut. Furthermore, a significant association between IgE sensitization against important food allergens and components of the fecal microflora could not be demonstrated. With aging changes occur in the intestinal microbiota [Proteus/Klebsiella and age (rho = -0.607) and Enterococcus and age (rho = -0.428)]. In two subjects of the AAEDS group Blastocystis hominis was found. The composition of natural intestinal microflora in children with AAEDS and NAAEDS was similar. Hence, there is no evidence of a role of the intestinal microflora with regard to the development of infant (food) allergy in children with AEDS. The possible consequences for allergic diseases later in life require further investigation.

Is Anisakis simplex responsible for chronic urticaria?

The association of chronic urticaria (CU) to parasitic infestations has been poorly studied. Recently, sensitization to the parasite larva Anisakis simplex has been described as the cause of acute urticaria and anaphylaxis. The aim of this work was to study the relationship between sensitization to A. simplex and CU. One hundred one patients with CU were studied. Data of possible contacts with A. simplex were collected and the usual CU study was performed. Furthermore, total and specific immunoglobulin E (IgE; Pharmacia CAP system IGE fluorescence enzyme immunoassay: CAP) to A. simplex, Ascaris lumbricoides, Echinococcus granulosus, and Toxocara canis were determined as well as skin-prick test with A. simplex and serology to E. granulosus. In accordance with the results of the CAP to A. simplex, the patients were divided into two groups, positive and negative, and, subsequently, subdivided into two other subgroups that were alternatively told to stop eating fish or seafood in their diet or to continue with their normal diet. Checkups were performed at 6, 12, and 18 months. Thirty-five percent of the patients had positive skin tests to A. simplex, and CAP to A. simplex was positive in 55%. The fish-eating habits, acute or chronic gastrointestinal disease, and the background of abdominal surgery were not related to the results of the CAP and/or skin test to A. simplex. A total of 21.8% of all the patients had detectable CAP to A. lumbricoides, 91% of whom had positive CAP to A. simplex. Three patients had specific IgE to T. canis and five patients had specific IgE to E. granulosus, in the absence of positive serology. All had specific IgE to A. simplex. Present infestation could not be proved in any of them. The clinical evolution and variations of CAP to A. simplex and of total IgE were not statistically different among the groups during the 6, 12, and 18 months of the study. The percentage of sensitization to A. simplex in patients with CU is elevated and determines the sensitization to other parasites because of cross-reactivity. We have not found any causal relationship between the presence of specific IgE to A. simplex and CU. The clinical importance of this finding in this disease is still undetermined.

An enteric helminth infection protects against an allergic response to dietary antigen.

Although helminths induce a polarized Th2 response they have been shown, in clinical studies, to confer protection against allergies. To elucidate the basis for this paradox, we have examined the influence of an enteric helminth infection on a model of food allergy. Upon Ag challenge, mice fed peanut (PN) extract plus the mucosal adjuvant cholera toxin (CT) produced PN-specific IgE that correlated with systemic anaphylactic symptoms and elevated plasma histamine. PN-specific IgE was not induced in helminth-infected mice fed PN without CT. Moreover, when PN plus CT was fed to helminth-infected mice, both PN-specific IgE and anaphylactic symptoms were greatly diminished. The down-regulation of PN-specific IgE was associated with a marked reduction in the secretion of IL-13 by PN-specific T cells. When helminth-infected PN plus CT-sensitized mice were treated with neutralizing Abs to IL-10, the PN-specific IgE response and anaphylactic symptoms were similar to, or greater than, those seen in mice that receive PN and CT alone. Taken together, these results suggest that helminth-dependent protection against allergic disease involves immunoregulatory mechanisms that block production of allergen-specific IgE.

Prevalence of and risk factors for IgE sensitization to Anisakis simplex in a Spanish population.

BACKGROUND: The number of allergic reactions to A. simplex reported in Spain has increased dramatically in the last decade. Nevertheless, there have been no studies of the prevalence of and possible risk factors for IgE sensitization to this parasite, possibly because suitably specific diagnostic methods have only recently become available. The objective was to investigate the prevalence of and risk factors for IgE sensitization to A. simplex in Galicia, a region of northwestern Spain with a population of about 3 million and high average fish consumption (78.5 g/person per day). METHODS: The study was performed with a random sample of 2801 healthy blood donors distributed in 53 geographic areas, proportional to the density of donors. IgE sensitization to A. simplex was tested by a capture ELISA method that has proved to be the most specific method currently available. RESULTS: The results showed a total of only 12 positive subjects, of whom five also showed IgG1 sensitization. All positive subjects and 101 randomly selected seronegative subjects were then included in a case-control study of risk factors for sensitization to A. simplex, based on a telephone interview about fish consumption (especially raw and undercooked fish). All seropositive subjects (but only 25% of seronegative subjects) reported consumption of undercooked fish or homemade raw-fish products. CONCLUSIONS: Our results strongly suggest that sensitization to A. simplex is caused only by live larvae, and not by allergens contained in fish tissues, and that ingestion of homemade boquerones (anchovies [Engraulis encrasicholus] in vinegar), and to a much lesser extent of undercooked fish, are the main risk factors for IgE sensitization to Anisakis in this region.

Anisakis and fish induced urticaria.

Skin tests using prepared Anisakis antigen and commercially available fish antigen were done. Also, specific IgE detection for Anisakis was done by RAST method. Two patients out of 20 showed positive skin test and positive RAST to larval Anisakis antigen, and negative skin test to fish antigen. These 2 patients were considered hypersensitive to Anisakis.