Insect Hypersensitivity Beyond Bee and Wasp Venom Allergy
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Review Allergologie select, Volume 4/2020 (97-104) Insect hypersensitivity beyond bee and wasp venom allergy Wolfgang Hemmer and Felix Wantke Floridsdorf Allergy Center, Vienna ©2020 Dustri-Verlag Dr. K. Feistle ISSN 2512-8957 DOI 10.5414/ALX02123E e-pub: November 30, 2020 Key words Abstract. The bites of blood-feeding peptides as well as various anticoagulant pro- blood-feeding insects insects regularly induce sensitization to sali- teins and digestive enzymes, which regularly – mosquito allergy – vary proteins and cause local hypersensitiv- induce an antigen-specific immune response mosquitoes – horse flies ity reactions in over 90% of the population, in the host [33, 49]. Some saliva components – black flies – biting representing either an IgE-mediated imme- midges – salivary diate wheal and flare reaction or a T cell- have been shown to have an immunomodula- allergens driven delayed papule. Long-lasting large tory effect in terms of Th2 polarization, pos- local reactions and bullous reactions may sibly as an evolutionary strategy to complete cause significant discomfort and reduction in blood meal more rapidly through inducing German version quality-of-life. Anaphylaxis is rarely report- local vasodilation [3]. ed though proven for several insects, above published in In the majority of people, either a transient Allergologie, all mosquitoes, horse flies, and kissing bugs. Vol. 43, No. 2/2020, Recently, salivary gland proteins have been immediate cutaneous reaction characterized pp. 73-81 thoroughly studied in some blood-feeding in- by wheals, erythema, and itching occurs with- sect species, and several allergens have been in a few minutes at the bite site (immediate identified. Interestingly, many of them be- reaction), or an indurated papule persisting for long to the same protein families as the well- several days develops after 12 – 24 hours (late known honeybee and wasp venom allergens (phospholipases, hyaluronidases, antigens 5, reaction) (Figure 1a, b, c). In Central Europe, serine proteases) though sequence identities > 70% of the population develops a cutane- are mostly low. There is still insufficient evi- ous immediate reaction after mosquito bites, dence for the proposed cross-reactivity be- 50 – 60% a late reaction, and 40% both [13]. tween salivary proteins from blood-feeding Similar values have been reported from Asia insects and Hymenoptera venom allergens. and Central America [11, 22]. The immediate wheal-and-flare reaction Introduction has been shown to represent a localized IgE- mediated type 1 reaction [23, 33]. In addition In contrast to bees and wasps, blood- to histamine, probably also capsaicin-sensi- feeding insects get less attention in allergo- tive sensory neurons play an essential role logical practice, because their bites primarily in bite-associated itching [29]. The hetero- cause cutaneous hypersensitivity reactions geneous delayed reactions have been little and rarely anaphylaxis. In addition, the usu- studied thus far. They probably represent ally mild bite reactions are often believed primarily T-cell-dependent type 4 reactions to be infections or toxic by nature, although and show non-specific infiltrates with macro- they actually represent true immune reac- phages, neutrophils, eosinophils and CD4+/ Received tions. The borderline between “normal” and CD8+ T lymphocytes. The saliva allergens June 26, 2019 “allergic” is vague. are already secreted by the insect during prob- accepted in revised form ing, so that skin reactions occur even if the November 14, 2019 feeding process is interrupted (Figure 1a, b). Correspondence to Cutaneous immediate and Cutaneous reactivity patterns often show Wolfgang Hemmer, PhD late reaction as ubiquitous a characteristic chronological sequence of Floridsdorf Allergy reaction patterns different reaction stages, starting with no re- Center, Pius-Parsch- action and progressing via delayed reaction Platz 1/3, 1210 Vienna, Austria The insect saliva secreted during the bite and immediate-type reaction to secondary [email protected] contains biogenic amines and vasoactive non-responsiveness (Table 1). Upon average Hemmer and Wantke 98 Figure 1. Skin reactions after bites by hematophagous insects. a, b: Immediate wheal and flare reaction during a bite provocation with a mosquito, “double” wheal after interruption of blood feeding; c: Type 4 late reactions (indurated papules) after multiple mosquito bites in an infant; d, e, f: Large local reactions after mosquito bites; g: Pearl-like arranged skin lesions caused by fleas bites; h: Bacterial superinfections due to scratching after multiple mosquito bites; i, j: Bullous skin reactions caused by flea bites after 3 (i) and 5 (j) days; k: Massive bullous bite reaction after a suspected black fly bite. Table 1. Stage theory of the progression of Large local reactions cutaneous hypersensitivity reactions to bites from hematophagous insects. Severe skin reactions in terms of delayed swellings up to > 10 cm in diameter, blisters Stage Immediate Delayed reaction reaction or necroses are found in 3 – 10% (Figure 1d, 1 (naive) – – e, f, i, j, k) [11, 13]. The pathomechanisms 2 – + underlying these reactions are poorly under- 3 + + stood. In some cases, skin reactions may be 4 + – accompanied by general symptoms like fever 5 (tolerance) – – and lymphadenopathy (“Skeeter syndrome”) [45]. Superinfections are not uncommon to occur (Figure 1h) and may require antibiotic exposure, 80 – 90% of children and adults therapy. remain in stages 2 – 4 for decades [30]. Only Papular urticaria is a chronic generalized ~ 5% achieve secondary tolerance [13, 22, cutaneous hypersensitivity reaction that is 26], especially in case of a very high num- seen especially in tropical regions in chil- ber of insect bites such as e.g. in Lapland, dren after mosquito, bug, and flea bites [10]. where up to 50% of the population become It is characterized by multiple, disseminated non-reactive [41]. The stage concept, which urticarial and papular lesions and is probably is largely based on epidemiological observa- due to the restimulation of resident T cells tions, was also experimentally proven in a following new bites. volunteer receiving a total of 2,000 mosquito Differential diagnosis of allergic hyper- bites over a 10-months period [33]. sensitivity includes severe bullous necrotic Insect hypersensitivity beyond bee and wasp venom allergy 99 Table 2. Blood-feeding insects causing allergic reactions. Scientific name English name Important genera c, s Diptera (flies and midges) Nematocera (midges) Culicidae mosquitoes Aedes, Culex, Anopheles c, s Simuliidae black flies Simulium c, s? Ceratopogonidae biting midges Culicoides, Forcipomyia c Phlebotomidae sand flies Phlebotomus, Lutzomyia c Brachycera (flies) Tabanidae horse flies, deer flies Haematopota, Tabanus, Chrysops c, s Glossinidae tsetse flies Glossina c, s Muscidae house/stable flies Stomoxys c Hippoboscidae louse flies, keds Hippobosca, Lipoptena c, s Siphonaptera (fleas) Pulicidae fleas Pulex, Ctenocephalides c Heteroptera (bugs) Reduviidae kissing bugs Triatoma c, s Cimicidae bed bugs Cimex lectularius c c: cutaneous reactions; s: systemic reactions. ulcerations associated with general symptoms (mosquitoes and flies) (Table 2). Among after mosquito bites in patients with NK-cell them, the mosquitoes (Culicidae) are most lymphocytosis and chronic EBV infection [2, important. In Central Europe, ~ 50 differ- 19]. This condition was described almost ex- ent species are known. 10 – 20% of them clusively in children from East Asia. EBV re- may play a role as relevant pests due to high activation in infected NK cells by mosquito- abundance, above all species from the genera specific CD4+ T cells has been discussed as Aedes and Culex (Figure 2a, b). The species the underlying pathomechanism. Similar ex- composition of mosquitoes varies locally aggerated local reactions have been observed and seasonally, which is clinically important also in other immune diseases affecting T-cell since cross-reactivity between different spe- immunity (e.g. CML, AIDS). cies may be limited [5, 34]. In Central Europe, stings by horse flies are most frequently caused by Haematopota Systemic reactions species (Common horse fly, cleg fly) (Figure 2e), and less frequently by the much larger Anaphylactic reactions are rare, possi- Tabanus species (giant horse flies) (Figure bly because of the small amount of antigen 2f). Chrysops species (deer flies) occasion- injected by blood-feeding insects. The most ally sting humans and may be confused with frequently reported triggers are horse flies wasps because of marked black and yellow and kissing bugs [14, 20, 25, 28, 38, 42], color patterns on their abdomen. whose salivary glands contain ~ 10 – 30 The 2 – 5 mm small, diurnal black flies times more protein than those of mosquitoes (Simuliidae) (Figure 2c), whose larvae de- [47]. Anaphylaxis has also been credibly velop in flowing waters, can occur in large documented after bites from mosquitoes, tse- numbers locally. The persistent delayed re- tse flies, and louse flies [32, 40]. A possible actions after multiple bites cause the clini- risk factor for anaphylactic reactions may be cal picture known as “simuliosis”. Both, the presence of mastocytosis [27, 40], which the black flies as well as the minute “biting is also a well-documented risk factor for se- midges” (Ceratopogonidae) (Figure 2d), vere anaphylaxis in Hymenoptera allergy. which are only 0.5 – 3 mm in size, have been intensively studied as the cause of summer Relevant