Isolation and characterization of Tha p 1, a major allergen from the pine processionary caterpillar Thaumetopoea pityocampa

Exploring oak processionary caterpillar induced lepidopterism (Part 1): unveiling molecular insights through transcriptomics and proteomics

Lepidopterism, a skin inflammation condition caused by direct or airborne exposure to irritating hairs (setae) from processionary caterpillars, is becoming a significant public health concern. Recent outbreaks of the oak processionary caterpillar (Thaumetopoea processionea) have caused noteworthy health and economic consequences, with a rising frequency expected in the future, exacerbated by global warming promoting the survival of the caterpillar. Current medical treatments focus on symptom relief due to the lack of an effective therapy. While the source is known, understanding the precise causes of symptoms remain incomplete understood. In this study, we employed an advanced method to extract venom from the setae and identify the venom components through high-quality de novo transcriptomics, venom proteomics, and bioinformatic analysis. A total of 171 venom components were identified, including allergens, odorant binding proteins, small peptides, enzymes, enzyme inhibitors, and chitin biosynthesis products, potentially responsible for inflammatory and allergic reactions. This work presents the first comprehensive proteotranscriptomic database of T. processionea, contributing to understanding the complexity of lepidopterism. Furthermore, these findings hold promise for advancing therapeutic approaches to mitigate the global health impact of T. processionea and related caterpillars.

Zootoxins and Domestic Animals: A European View

Zootoxins are produced by venomous and poisonous species and are an important cause of poisoning in companion animals and livestock in Europe. Little information about the incidence of zootoxin poisoning is available in Europe, with only a few case reports and review papers being published. This review presents the most important zootoxins produced by European venomous and poisonous animal species responsible for poisoning episodes in companion animals and livestock. The main zootoxin-producing animal species, components of the toxins/venoms and their clinical effects are presented. The most common zootoxicoses involve terrestrial zootoxins excreted by the common toad, the fire salamander, the pine processionary caterpillar, and vipers. The lack of a centralized reporting/poison control system in Europe makes the evaluation of the epidemiology of zootoxin-induced poisonings extremely difficult. Even if there are many anecdotal reports in the veterinary community about the exposure of domestic animals to terrestrial and marine zootoxins, the number of published papers regarding these toxicoses is low. Climate change and its consequences regarding species distribution and human-mediated transportation are responsible for the emerging nature of some intoxications in which zootoxins are involved. Although new venomous or poisonous animal species have emerged in regions where they were previously unreported, zootoxins produced by native species remain the main concern in Europe. The diversity of poisonous and venomous animal species and the emerging nature of certain poisonings warrant the continuous update to such knowledge by veterinary professionals and animal owners. This review offers an overview about zootoxin-related poisonings in domestic animals in Europe and also provides important information from a health perspective.

Horizontal gene transfer underlies the painful stings of asp caterpillars (Lepidoptera: Megalopygidae)

Larvae of the genus Megalopyge (Lepidoptera: Zygaenoidea: Megalopygidae), known as asp or puss caterpillars, produce defensive venoms that cause severe pain. Here, we present the anatomy, chemistry, and mode of action of the venom systems of caterpillars of two megalopygid species, the Southern flannel moth Megalopyge opercularis and the black-waved flannel moth Megalopyge crispata. We show that megalopygid venom is produced in secretory cells that lie beneath the cuticle and are connected to the venom spines by canals. Megalopygid venoms consist of large aerolysin-like pore-forming toxins, which we have named megalysins, and a small number of peptides. The venom system differs markedly from those of previously studied venomous zygaenoids of the family Limacodidae, suggestive of an independent origin. Megalopygid venom potently activates mammalian sensory neurons via membrane permeabilization and induces sustained spontaneous pain behavior and paw swelling in mice. These bioactivities are ablated by treatment with heat, organic solvents, or proteases, indicating that they are mediated by larger proteins such as the megalysins. We show that the megalysins were recruited as venom toxins in the Megalopygidae following horizontal transfer of genes from bacteria to the ancestors of ditrysian Lepidoptera. Megalopygids have recruited aerolysin-like proteins as venom toxins convergently with centipedes, cnidarians, and fish. This study highlights the role of horizontal gene transfer in venom evolution.

Processionary caterpillar reactions in Southern Italy forestry workers: description of three cases

Background

Processionary caterpillar (PC), also named Thaumatopea pityocampa, has been reported to cause hypersensitivity reactions after contact with a toxin contained in hair-like bristles which cover this insect. Occupational exposure to PC is underestimated in outdoor workers and especially in forestry workers (FW) and is globally diffusing because of rising temperatures.

Cases presentation

We present the first three cases of FW from Sicily, a Southern Italy (SI) region, which reported hypersensitivity reactions due to exposure to PC infested trees. These cases were identified by the occupational health physician during the annual screening of FW working in the Mountains of north-eastern Sicily. Interviewing a population of 630 FW, 1 male and 2 females reported direct contact skin reactions together with airborne contact reactions to PC hairs causing mild respiratory symptoms in two cases and ocular symptoms in one case, which needed treatment with systemic corticosteroids and antihistamines.

Conclusions

This is the first report of hypersensitivity reactions in SI FW due to occupational exposure to PC. Further screenings not only in FW but also in other populations of outdoor workers are needed in order to assess the real incidence of contact and airborne reactions due to occupational exposure to PC. Though so far no correlation has been found with atopy, it seems apparent that the reactions occur in susceptible subjects; further research is needed for a correct diagnosis and to identify possible desensitization procedures.

Respiratory sensitization to insect allergens: Species, components and clinical symptoms

Airborne insect particles have been identified as an important cause of respiratory allergies, including allergic asthma and rhinitis. In the literature, the significance of respiratory exposure to insect particles as a cause of occupational allergy has been well-documented. Indeed, many cases of occupational allergy have been reported including allergy to the larvae of flies and moths in anglers and occupationally exposed workers, to grain pests in bakers or other workers handling grains, and to crickets and/or locusts in researchers and workers in aquaculture companies. Furthermore, the prevalence of sensitization to insect allergens is considerably high among patients with asthma and/or rhinitis who are not occupationally exposed to insects, suggesting the clinical relevance of exposure to insects in indoor and outdoor environmental non-occupational settings. Exposure to cockroaches, a well-studied indoor insect, is associated with cockroach sensitization and the development and exacerbation of asthma. Booklice, another common indoor insect, were recently identified as a significant sensitizer of asthmatic patients in Japan and India, and potentially of asthma patients living in warm and humid climates around the world. Lip b 1 was identified as an allergenic protein contributing to the species-specific sensitization to booklice. Moths are considered a significant seasonal outdoor allergen and their allergens are considered to have the highest sensitization rate among Japanese patients. However, other than cockroaches, allergenic insect proteins contributing to sensitization have not been fully characterized to date.

Identification of Novel Toxin Genes from the Stinging Nettle Caterpillar Parasa lepida (Cramer, 1799): Insights into the Evolution of Lepidoptera Toxins

Simple Summary

Many caterpillar species can produce toxins that cause harmful reactions to humans, varying from mild irritation to death. Currently, there is very limited knowledge about caterpillar toxin diversity, because only a few species have been investigated. We used the transcriptome technique to identify candidate toxin genes from the nettle caterpillar Parasa lepida (Cramer, 1799). It is a common pest of oil palm, coconut, and mango in South and South-East Asia, which can cause severe pain and allergic responses to those in contact with them. We reported 168 candidate toxin genes. Most of them are members of the toxin genes families commonly recruited in animal venoms such as serine protease and serine protease inhibitors. However, we identified 21 novel genes encoding knottin-like peptides expressed at a high level in the transcriptome. Their predicted 3D structures are similar to neurotoxins in scorpion and tarantula. Our study suggests that P. lepida venom contains diverse toxin proteins that potentially cause allergic reactions and pain. This study sheds light on the hidden diversity of toxin proteins in caterpillar lineage, which could be future fruitful new drug sources.

Abstract

Many animal species can produce venom for defense, predation, and competition. The venom usually contains diverse peptide and protein toxins, including neurotoxins, proteolytic enzymes, protease inhibitors, and allergens. Some drugs for cancer, neurological disorders, and analgesics were developed based on animal toxin structures and functions. Several caterpillar species possess venoms that cause varying effects on humans both locally and systemically. However, toxins from only a few species have been investigated, limiting the full understanding of the Lepidoptera toxin diversity and evolution. We used the RNA-seq technique to identify toxin genes from the stinging nettle caterpillar, Parasa lepida (Cramer, 1799). We constructed a transcriptome from caterpillar urticating hairs and reported 34,968 unique transcripts. Using our toxin gene annotation pipeline, we identified 168 candidate toxin genes, including protease inhibitors, proteolytic enzymes, and allergens. The 21 P. lepida novel Knottin-like peptides, which do not show sequence similarity to any known peptide, have predicted 3D structures similar to tarantula, scorpion, and cone snail neurotoxins. We highlighted the importance of convergent evolution in the Lepidoptera toxin evolution and the possible mechanisms. This study opens a new path to understanding the hidden diversity of Lepidoptera toxins, which could be a fruitful source for developing new drugs.

Caterpillar Venom: A Health Hazard of the 21st Century

Caterpillar envenomation is a global health threat in the 21st century. Every direct or indirect contact with the urticating hairs of a caterpillar results in clinical manifestations ranging from local dermatitis symptoms to potentially life-threatening systemic effects. This is mainly due to the action of bioactive components in the venom that interfere with targets in the human body. The problem is that doctors are limited to relieve symptoms, since an effective treatment is still lacking. Only for Lonomia species an effective antivenom does exist. The health and economical damage are an underestimated problem and will be even more of a concern in the future. For some caterpillar species, the venom composition has been the subject of investigation, while for many others it remains unknown. Moreover, the targets involved in the pathophysiology are poorly understood. This review aims to give an overview of the knowledge we have today on the venom composition of different caterpillar species along with their pharmacological targets. Epidemiology, mode of action, clinical time course and treatments are also addressed. Finally, we briefly discuss the future perspectives that may open the doors for future research in the world of caterpillar toxins to find an adequate treatment.

Venomous caterpillars: From inoculation apparatus to venom composition and envenomation

Envenomation by the larval or pupal stages of moths occurs when the victim presses their hairs. They penetrate the subcutaneous tissue, releasing toxins such as proteolytic enzymes, histamine and other pro-inflammatory substances. Cutaneous reactions, including severe pain, oedema and erythema are frequent local manifestations of caterpillar envenomation, but, in some cases, the reactions can evolve into vesicles, bullae, erosions, petechiae, superficial skin necrosis and ulcerations. Alternatively, some individual can develop allergic reactions, renal failure, osteochondritis, deformity and immobilization of the affected joints and intracerebral bleeding. Caterpillars produce venom to protect themselves from predators; contact with humans is accidental and deserves close attention. Their venoms have not been well studied, except for toxins from some few species. The present review brings together data on venomous caterpillars of moths, primarily addressing the available literature on diversity among the different families that cause accident in humans, the structures used in their defense, venom composition and clinical aspects of the envenomations. Understanding the molecular mechanisms of action of caterpillars' toxins may lead to the development of more adequate treatments.

Proteome Analysis of Urticating Setae From Thaumetopoea pityocampa (Lepidoptera: Notodontidae)

Thaumetopoea pityocampa (Denis & Schiffermüller) (Lepidoptera: Notodontidae) is harmful to conifer trees because of defoliation and to public health because of the release of urticating setae from the caterpillars. Contact with setae by humans and domestic animals induces dermatitis, usually localized to the exposed areas. Recent studies demonstrated the presence of a complex urticating mechanism where proteins present in the setae may play a role as activators of immune responses. Yet, limited information is available at present about the proteins occurring in the setae of T. pityocampa. Using a refined method for protein extraction from the setae, and a combination of liquid chromatography tandem-mass spectrometry (LC-MS/MS), de novo assembly of transcriptomic data, and sequence similarity searches, an extensive data set of 353 proteins was obtained. These were further categorized by molecular function, biological process, and cellular location. All the 353 proteins identified were found to match through BLAST search with at least one Lepidoptera sequence available in databases. We found the previously known allergens Tha p 1 and Tha p 2 described from T. pityocampa, as well as enzymes involved in chitin biosynthesis, one of the principal components of the setae, and serine proteases that were responsible for inflammatory and allergic reactions in other urticating Lepidoptera. This new proteomic database may allow for a better understanding of the complexity of allergenic reactions due to T. pityocampa and to other Lepidoptera sharing similar defense systems.

The allergenic protein Tha p 2 of processionary moths of the genus Thaumetopoea (Thaumetopoeinae, Notodontidae, Lepidoptera): Characterization and evolution

The allergenic Tha p 2 protein has been extracted recently from the urticating setae of the pine processionary moth Thaumetopoea pityocampa. In the present paper, we test for the occurrence of this protein in other Thaumetopoeinae, with a particular focus on members of the genus Thaumetopoea, as well as unrelated moth species, to better understand the physicochemical properties of the protein, the nature of encoding genes and their evolutionary history. Tha p 2 is encoded by the intronless gene Tha p 2 that is restricted to the processionary moths (Thaumetopoeinae, Notodontidae, Lepidoptera). Most of the species present two isoforms of Tha p 2 that can be interpreted as the result of heterozygosity in the single gene. The only exception is represented by Thaumetopoea wilkinsoni, in which 20 different isoforms occur in a single specimen, leading to the conclusion that, at least in this species, multiple copies of Tha p 2 exist. Serine, glycine, cysteine and leucine are abundant in Tha p 2, a protein well conserved among processionary moths. The predicted secondary structures of Tha p 2 indicate the presence of 3 α-helices and six β-barrels. Finally, the evolution of the gene and the protein was characterized by a combination of positive and negative selection, with the latter being more evident.

Size and dispersion of urticating setae in three species of processionary moths

Larvae of the processionary moths of the Palaearctic region bear urticating setae that are released against vertebrate predators, especially insectivorous birds. A few species are pests of forest and urban trees and, consequently, may threaten human and animal health during outbreaks, causing dermatitis, conjunctivitis and respiratory distress. Although some studies provide detailed information about the setae, particularly those of the pine processionary moth Thaumetopoea pityocampa, there is little knowledge on the morphological traits of the setae and their release by the larvae. In the present study we identify major traits of the setae of 3 species of processionary moth, T. pityocampa, T. pinivora and T. processionea, which are potentially helpful in the understanding of setae dynamics in the environment: (i) diameter and length of setae and (ii) analysis of dynamical properties of the setae in the airborne state. Setae are highly variable in size, with bimodal distribution in T. pityocampa and T. pinivora; in these 2 species, short and long setae are interspersed within the integument fields where they occur. The difference in the seta size has important consequences in dispersion, as smaller setae can spread 5 times further than their bigger counterparts. This information is relevant for a full understanding of the defensive importance of larval setae against natural enemies of the processionary moths, as well for elucidating the importance of the processionary setae as air pollutants, both close to the infested trees and at longer distances.

[Public health pests. Arthropods and rodents as causative disease agents as well as reservoirs and vectors of pathogens]

Globally, infectious diseases pose the most important cause of death. Among known human pathogenic diseases, approximately 50 % are zoonoses. When considering emerging infectious diseases separately 73 % currently belong to the group of zoonoses. In Central Europe, hard ticks show by far the biggest potential as vectors of agents of human disease. Lyme borreliosis, showing an estimated annual incidence between 60,000 and 214,000 cases is by far the most frequent tick-borne disease in Germany. Continually, formerly unknown disease agents could be discovered in endemic vector species. Additionally, introduction of new arthropod vectors and/or agents of disease occur constantly. Recently, five mosquito species of the genus Aedes have been newly introduced to Europe where they are currently spreading in different regions. Uncommon autochthonous transmission of dengue and chikungunya fever viruses in Southern Europe could be directly linked to these vector species and of these Ae. albopictus and Ae. japonicus are currently reported to occur in Germany. The German Protection against Infection Act only covers the control of public health pests which are either active hematophagous vectors or mechanical transmitters of agents of diseases. Use of officially recommended biocidal products aiming to interrupt transmission cycles of vector-borne diseases, is confined to infested buildings only, including sewage systems in the case of Norway rat control. Outdoor vectors, such as hard ticks and mosquitoes, are currently not taken into consideration. Additionally, adjustments of national public health regulations, detailed arthropod vector and rodent reservoir mapping, including surveillance of vector-borne disease agents, are necessary in order to mitigate future disease risks.

[Skin reactions on exposure to the pine processionary caterpillar (Thaumetopoea pityocampa)]

The pine processionary caterpillar is the larval form of the Thaumetopoea pityocampa moth. Mediterranean forests regularly suffer plagues of this insect, which has been moving north as a result of global warming. When the small urticating hairs that develop during the last 3 larval stages are shed and can become airborne. If they come in contact with skin, they can cause a variety of reactions, notably contact urticaria and papular rashes. Irritation can also occur if the hairs lodge in the mucosa of the conjunctiva or in the respiratory tract. Several cases of anaphylactic reactions have been reported in recent years. Mechanical (irritative) mechanisms may be involved in the pathogenesis of lesions, or immunoglobulin E-mediated allergic hypersensitivity reactions may be implicated when the process is rapid, recurrent, and progressively more severe.

Urticating hairs in arthropods: their nature and medical significance

The ecological phenomenon of arthropods with defensive hairs is widespread. These urticating hairs can be divided into three categories: true setae, which are detachable hairs in Lepidoptera and in New World tarantula spiders; modified setae, which are stiff hairs in lepidopteran larvae; and spines, which are complex and secretion-filled structures in lepidopteran larvae. This review focuses on the true setae because their high density on a large number of common arthropod species has great implications for human and animal health. Morphology and function, interactions with human tissues, epidemiology, and medical impact, including inflammation and allergy in relation to true setae, are addressed. Because data from epidemiological and other clinical studies are ambiguous with regard to frequencies of setae-caused allergic reactions, other mechanisms for setae-mediated disease are suggested. Finally, we briefly discuss current evidence for the adaptive and ecological significance of true setae.

Immune response profiles after caterpillar exposure: a case report

Rationale

The role of the immune response to caterpillar exposure is not well described. This case study is the first to report a patient who presented with an allergic reaction after exposure to the larvae of the sycamore tussock moth, Halysidota harrisii Walsh, 1864.

Methods

Blood was collected from an allergic asthmatic adult (m/42 y/o) at 2 hrs – 2 wks after contact urticaria with associated dyspnea after exposure to the larvae of the sycamore tussock moth, Halysidota harrisii Walsh, 1864. Distributions of blood lymphocytes (CD4⁺, CD8⁺, CD8⁺CD60⁺, CD19⁺, CD23⁺, CD16/56⁺, CD25, CD45RA⁺, CD45RO⁺), monocytes (CD1d⁺), levels of serum immunoglobulins (IgM, IgG, IgA, IgE), and cytokines (IFN-γ, IL-4, TNF-α) were studied (flow cytometry, nephelometry, UniCAP Total IgE Fluoroenzymeimmunoassay, cytokine ELISA, clinical toxicology).

Results

Numbers of CD4⁺ T cells, CD25⁺ cells, CD19⁺ B cells, and CD1d⁺ monocytes decreased (22, 27, 33, 20%, respectively) one week post reaction, CD45RA⁺ naïve T cells decreased at 36 hours (21%),while CD8⁺CD60⁺ T cells and CD23⁺ cells decreased 48 hrs (33, 74%, respectively) post reaction. In contrast, numbers of CD16/56⁺ NK precursor cells increased (60%) 12 hrs, then decreased (65%) 48 hrs post reaction; other lymphocyte subsets were unaffected. Serum IgM, IgG and IgA were within normal range; however, serum IgE demonstrated a bimodal elevation at 2 hrs (15%) and one week post reaction. Levels of IFN-γ, IL-4, and TNF-α were not detected in serum pre-exposure (<1.0–4.0 pg/mL). However, high levels of IFN-γ (187–319 pg/mL) and TNF-α (549–749 pg/mL) were detected in serum 24–36 hrs and 3.5–24 hrs post reaction, respectively. In contrast, levels of IL-4 were undetected (<1.0 pg/mL) in serum at all time points.

Conclusions

Exposure to the larvae of the sycamore tussock moth, Halysidota harrisii Walsh, 1864 may result in increased cytokine levels and blood CD16/56⁺ NK precursor cells.

Systemic allergic reaction to tree processionary caterpillar in children

Contact with the tree processionary caterpillar or ingestion/inhalation of its airborne toxin-containing hairs and spines may cause a direct histamine-releasing or IgE-mediated allergic reaction in humans. The most common manifestations are urticaria and dermatitis; systemic manifestations such as respiratory involvement and anaphylaxis have been reported mainly in foresters. We describe a 12-year-old child who was presented to the emergency department with systemic allergic reaction (pruritic rash, conjunctival hyperemia, dyspnea, and wheezing), which eventually proved to be due to exposure to the pine tree processionary caterpillar. The diagnosis was made only after the child's repeated exposure to the caterpillar. Tree processionary caterpillar should be added to the list of causes of systemic allergic reactions in children, especially in endemic areas, and medical staff should be alerted the range of clinical manifestations to ensure prompt diagnosis and treatment.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

Life-threatening facial edema due to pine caterpillar mimicking an allergic event

BACKGROUND

Approximately 150 species of Lepidoptera have been described as causing damage to human skin. One of these species is the pine processionary caterpillar, which is responsible for dermatitis, contact urticaria, ocular lesions and rarely respiratory signs and anaphylactic reactions through IgE-mediated or non-IgE-mediated mechanisms. We report a pediatric case of severe orofacial edema mimicking an allergic reaction after ingestion of a pine processionary caterpillar; urgent airway intubation was required.

CASE REPORT

A 15-month-old boy was sleeping under a pine tree when his mother noted a pine caterpillar on his tongue. Because of rapidly developing facial swelling and respiratory distress, the infant was first taken to a local hospital where he received intravenous dexamethasone and pheniramine hydrogen maleate. On arrival at our emergency department, diffuse swelling and edema involving the tongue, perioral, nasal and perimandibular regions, and neck was noted, requiring urgent orotracheal intubation. There were no findings of anaphylaxis. The results of skin prick tests and specific IgE to common aero- and food allergens were negative. A skin prick test with extract of pine caterpillar was also negative. Prednisolone and pheniramine hydrogen maleate were administered for 7 days. The child gradually improved and was successfully extubated 4 days later.

CONCLUSION

Although oral contact with a pine processionary caterpillar in the form of ingestion is rare, it may cause significant local reaction and airway compromise mimicking an allergic event. In this situation, early intubation to maintain airway patency is a life-saving measure.

Allergy to pine processionary caterpillar (Thaumetopoea pityocampa) in children

Contact with pine processionary caterpillar (Thaumetopoea pityocampa) induces dermatitis usually located in exposed areas through a toxic-irritative mechanism. Over the last few years an immediate hypersensitivity mechanism have mainly been demonstrated in adult patients. However, there are few studies carried out in children.

OBJECTIVE

To evaluate a group of 16 children who experienced allergic reactions after exposure to pine processionary caterpillar.

PATIENTS AND METHODS

All patients underwent allergy testing through skin prick test. Serum specific IgE determination was performed by EAST technique. The molecular mass of the IgE -binding bands was studied by SDS-PAGE Immunoblotting.

RESULTS

Skin prick test with the caterpillar extract was positive in all patients. Specific IgE was positive (higher than 0.35 kU/L) in 15 patients' sera. Western blotting showed several IgE-binding bands with molecular mass values ranging from 17.5 to 168 kDa. Electrophoretic mobility of some of the relevant allergens was related to the conditions of sample preparation (reduced or non-reduced).

CONCLUSIONS

The results of this study demonstrate the existence of an allergic IgE-mediated mechanism caused by pine processionary caterpillar proteins. Airborne urticating hairs of this animal should be considered as seasonal inhalant allergen, which is able to induce allergic pathologies in children who frequent pine areas.

Systemic immediate allergic reactions to arthropod stings and bites

Most of the encounters with biting and stinging insects result in more or less pronounced localized reactions. Typically, urticarial wheals and papular reactions are observed. Less often local bullous or hemorrhagic or disseminated papular reactions, particularly in children and immunologically naive adults, may be seen. With the exception of bee and wasp venom allergies, immediate-type allergic reactions to arthropod stings and bites are rare. Systemic IgE-mediated hypersensitivity has also been reported from additional hymenoptera species, e.g. hornets, bumble bees and ants. Rare are systemic reactions to mosquitoes, flies or kissing bugs and exceptional from ticks, bed bugs, moths, caterpillars and spiders. A major problem is the often lacking standardization of extracts for skin testing and for the determination of specific IgE. Some of the allergens have been characterized and few of them synthesized using recombinant techniques. Most investigations have been made with whole-body extracts or extracts from salivary glands, while desensitization has rarely been attempted. Currently, primary prevention by avoidance of stings and bites, and adequate instruction of sensitized individuals in the use of emergency drugs are mandatory.

Severe tongue necrosis associated with pine processionary moth (Thaumetopoea wilkinsoni) ingestion in three dogs

The pine processionary moth (Thaumetopoea wilkinsoni) is an insect of medical significance in the eastern Mediterranean. This report describes three exposure cases in dogs due to ingestion of this moth's caterpillars in Israel. All three dogs were observed in direct contact with caterpillars or pinecones in infested gardens. The disease course and progression of signs were acute in all three cases, and included vomiting and severe tongue swelling. Physical examination findings included hyperthermia, tachypnoea, respiratory distress, cyanosis and tongue oedema, labial angioedema, ptyalism, bilateral submandibular lymphadenomegaly and conjunctivitis. Severe tongue necrosis and sloughing of its distal portion occurred 2-5 days after admission to the hospital. All dogs recovered and were discharged within 2-7 days of admission. Two staff members, attending one of the dogs, experienced an itchy rash and wheals on their arms, wrists and necks. To the best of our knowledge, this should be the first report of severe oral lesions and tongue necrosis due to contact with T. wilkinsoni caterpillars.

Occupational immunologic contact urticaria from pine processionary caterpillar (Thaumetopoea pityocampa): experience in 30 cases

Cutaneous lesions caused by the pine processionary caterpillar Thaumetopoea pityocampa (TP) are frequent in pinewood areas. In the present study, 30 patients diagnosed with occupational immunologic urticaria from this caterpillar were included. Immediate hypersensitivity was demonstrated by performing prick and IgE-immunoblotting tests. Workers were grouped according to their common tasks. Occupations at risk of exposure to TP were pine-cone collectors/woodcutters (14), farmers/stockbreeders (8), other forestry personnel (4), construction workers (2), residential gardeners (1) and entomologists (1). Besides contact urticaria, angioedema (60%), papular lesions of several days of evolution (30%) and anaphylactic reactions (40%) were also detected. The most frequently detected molecular weight bands by immunoblot were 15 (70%), 17 (57%) and 13 kDa (50%). The appearance of isolated bands corresponds with the least serious cases. Only 8 subjects had bands higher than 33 kDa, which was present in the 3 most severe cases of anaphylactic reactions. By presenting these cases, we wish to offer the largest series reported so far of occupational immunologic contact urticaria caused by TP. We include the first cases described in certain occupations, some of them not directly related to forestry work. Pine-cone or resin collectors, woodcutters, farmers and stockbreeders were the most frequently and severely affected workers.

Non-occupational allergy caused by the pine processionary caterpillar (Thaumetopoea pityocampa)

Contact with the pine processionary caterpillar induces dermatitis, usually located in exposed areas, and, less frequently, ocular lesions through a toxic-irritative mechanism. Recently, the existence of an immediate hypersensitivity mechanism has been demonstrated, mainly in occupationally exposed patients.

OBJECTIVE

To present four patients who experienced allergic reactions (urticaria-angioedema and rhinitis-asthma) after non-occupational exposure to pine processionary caterpillar.

PATIENTS AND METHODS

The four patients underwent allergy testing through skin prick tests (SPT), specific IgE detection and SDS-PAGE immunoblotting. One patient also underwent a specific bronchial challenge test with the pine processionary antigen.

RESULTS

In all patients, both SPT with the caterpillar extract and specific IgE were positive. Western blotting showed several IgE-binding bands with molecular mass values ranging from 18 to 107 kDa. A shift in the electrophoretic mobility of some of the relevant allergens occurred under the presence of a reductive agent (beta -mercaptoethanol). The specific bronchial challenge test with pine processionary antigen performed in one of the patients also produced positive results.

CONCLUSIONS

The results of this study show an immunologic IgE-mediated immediate hypersensitivity mechanism in these reactions. The processionary caterpillar's airborne urticating hairs or spicules should be considered, at least in some locations, not only as contact and occupational allergens, but also as seasonal aeroallergens.

Caterpillar Dermatitis in Two Siblings due to the Larvae of Thaumetopoea processionea L., the Oak Processionary Caterpillar

Two siblings, 16 months and 5 years of age, came into contact with the urticating hairs (setae) of oak processionary caterpillars, the larvae of Thaumetopoea processionea L., when the family moved to a suburb of Vienna, where mass gradation of T. processionea had started the year before. The setae were being spread by the wind from an infested oak tree in the neighbourhood. Both children repeatedly suffered bouts of dermatitis during the 10 weeks of the larval development. Owing to the fact that T. processionea often infests oak trees, whether isolated or at the edges of forests, there is a high likelihood of people being affected. Children frequently explore their surroundings and are at an even greater risk of developing lepidopterism. Caterpillar dermatitis should therefore be taken into consideration in the differential diagnosis of a pruritic rash in infants from regions with caterpillar-infested trees, especially during the larval development of T. processionea .