Bullous Allergic Hypersensitivity to Bed Bug Bites Mediated by IgE against Salivary Nitrophorin

Bed Bug Infestation: An Updated Review

In the past decade, there has been a global resurgence of bed bug infestations, especially in developed countries. Proper awareness and identification of bed bug infestations are essential to guide treatment and eradication. The purpose of this article is to familiarize physicians with bed bug bites so that they can effectively diagnose, treat, and address questions about bed bug bites and infestations. Bed bug bites are often painless. Typical reactions include pruritic, erythematous maculopapules occurring in clusters or in a linear or curvilinear distribution in exposed areas of the body. A small red punctum may be visualized at the center of the bite mark. Lesions that appear three in a row and papules on the upper eyelid associated with erythema and edema are highly suggestive of bites from bed bugs. Exaggerated local reactions such as vesicles, urticarial wheals, urticarial perilesional plaques, diffuse urticaria, bullae, and nodules may occur in previously sensitized individuals. Reactions to bed bug bites are self-limited. As such, treatment is mainly symptomatic. Topical pramoxine and oral antihistamines can be used to alleviate pruritus. Topical corticosteroids can be used for significant eruptions to control inflammation and pruritus, and to hasten resolution of the lesions. Integrated pest management, an approach for the eradication of bed bugs, includes monitoring devices (active monitors include the use of heat or carbon dioxide attractants and passive monitors include the use of sticky pads for trapping), and judicious use of nonchemical and chemical treatments known to be effective. Nonchemical interventions include keeping affected areas clean and free of clutter, vacuuming, washing linens with hot water, caulking wall holes and cracks where bugs can hide, proper disposal of highly infested items, and placement of bed bug traps/interceptors at the base of beds and furniture. Chemical interventions involve the use of insecticides such as synthetic pyrethroids, silicates, insect growth disruptors, carbamates, organophosphates, neonicotinoids, diethyl-meta-toluamide, chlorfenapyr, fipronil and plant essential oils. Insecticides should be used with caution to prevent over-exposure and toxicity (in particular, cardiovascular and neurologic toxicity), especially if there are young children around. It is important to note that multiple mechanisms of insecticide resistance exist and as such, chemical treatment should only be undertaken by trained professionals who understand the current literature on resistance. Both nonchemical and chemical technologies should be combined for optimal results. Bed bug infestations may cause diverse dermal reactions, stigmatization, poor self-esteem, emotional stress, anxiety, significant adverse effect on quality of life, and substantial socioeconomic burden to society. As such, their rapid detection and eradication are of paramount importance. Consultation with a professional exterminator is recommended to fully eradicate an infestation.

Bedbug salivation patterns during hematophagy in the skin of a mammalian host

Cimex lectularius (Hemiptera:Cimicidae) infestations have increased over the past decades in several parts of the world, constituting a major urban pest with no reversion signs. The impact on human health caused by these insects, commonly known as bedbugs, is associated with their obligatory hematophagous habit. Allergies induced by hematophagous arthropod bites are related to the deposition of salivary molecules in the host tissues. Many reports of humans developing severe allergic reactions due to bedbug bites have been recorded, however, there is limited information on the salivation of bedbugs on the host, which was the objective of this study. C. lectularius females were fed on blood containing acridine orange fluorochrome, which labeled the principal salivary glands content. The salivation pattern of bedbugs was investigated using intravital microscopy during its blood meal on the ear skin of hairless mice. Saliva deposition occurred during all insect blood-feeding phases, beginning as soon as the mouthpart touched the host skin. During the probing phase, saliva was deposited in large quantities in the host dermis. In contrast, during the engorgement phase (which represents the largest blood meal of the insects), saliva was released at a much slower rate. The apparent release of saliva into the cannulated vessel and/or adjacent tissue occurs only sporadically during insect blood ingestion. However, a small area (spot) of fluorescence was detected around the proboscis tip during this feeding phase. An interesting feature of bedbugs is that they release saliva inside and outside the vessels without removing their mouthparts from the vessel lumen. This is an effective feeding strategy because it does not interrupt blood ingestion and decreases the mouthparts movements on the host's skin, minimizing the damage to tissues and contact time with the host (feeding time).

Association between bed bugs and allergic reactions

AIMS

To evaluate whether bed bugs are associated with allergic reactions in patients seen in the emergency department (ED).

METHODS AND RESULTS

This retrospective study included data from 9 EDs in Ohio between February 2011 and February 2017. The study comprised 332 patients with bed bug infestation matched 1:15 with 4952 control patients without bed bugs on the basis of age, sex and the presenting ED. Compared with uninfested patients, patients infested with bed bugs were more likely to have an ED or inpatient diagnosis of pruritus, hives or urticaria (odds ratio [OR], 9.12 [95% CI, 3.41-24.42]) and to be treated in the ED with an antihistamine (OR, 3.20 [95% CI, 1.87-5.50]) or albuterol (OR, 1.59 [95% CI, 1.07-2.36]) (P ≤ .02 for all). There were no significant differences in the rates of anaphylaxis and angioedema diagnosed in patients with and without bed bugs, which occurred in <1% in both groups.

CONCLUSION

Bed bug-infested patients are more likely to be diagnosed and treated for itchy cutaneous rashes, but are not clearly associated with more severe allergic reactions.

Linear patterns of the skin and their dermatoses

Knowledge about the linear patterns of the skin is a key competence of dermatologists. Four major groups of linear patterns can be distinguished: Langer lines, dermatomes, Blaschko lines and exogenous patterns. Langer lines run in the direction of the underlying collagen fibers (least skin tension) and play an important diagnostic role for some exanthematous skin diseases. In the thoracodorsal region, the distribution of the Langer lines gives rise to what is referred to as a 'Christmas tree pattern'. A dermatome is an area of skin that is supplied by a single spinal nerve. Disorders with a neuronal origin follow this pattern of distribution. The lines of Blaschko delineate the lines of migration of epidermal cells during embryogenesis. Exogenous linear patterns are caused by external factors. The present CME article will highlight important skin disorders that primarily present in the form of one of the aforementioned patterns. In addition, we will also address skin conditions that may secondarily follow with these patterns (or distinctly not do so) as the result of various mechanisms such as the Koebner phenomenon, reverse Koebner phenomenon, and Wolf's isotopic response.

Insect hypersensitivity beyond bee and wasp venom allergy

The bites of blood-feeding insects regularly induce sensitization to salivary proteins and cause local hypersensitivity reactions in over 90% of the population, representing either an IgE-mediated immediate wheal and flare reaction or a T cell-driven delayed papule. Long-lasting large local reactions and bullous reactions may cause significant discomfort and reduction in quality-of-life. Anaphylaxis is rarely reported though proven for several insects, above all mosquitoes, horse flies, and kissing bugs. Recently, salivary gland proteins have been thoroughly studied in some blood-feeding insect species, and several allergens have been identified. Interestingly, many of them belong to the same protein families as the well-known honeybee and wasp venom allergens (phospholipases, hyaluronidases, antigens 5, serine proteases) though sequence identities are mostly low. There is still insufficient evidence for the proposed cross-reactivity between salivary proteins from blood-feeding insects and Hymenoptera venom allergens.

Human immunoglobulin G responses to Cimex lectularius L. saliva

AIMS

To investigate the immunoglobulin (Ig) G response after being fed upon by Cimex lectularius L.

METHODS AND RESULTS

Participants were fed upon by three male C lectularius insects weekly for a month. Blood was obtained before the feeding and at the last feeding, which was used for immunoblots against bed bug salivary gland extract, with antihuman Immunoglobulin G (IgG) secondary antibodies. No consistent IgG changes developed in 11 humans serially fed upon by C lectularius. Two participants had new IgG responses to proteins at molecular weights of approximately 12-13 kDa, and one had an IgG response to a protein at approximately 40 kDa. At the last study visit, more intense IgG bands to proteins at molecular weights of 12-13 kDa had developed in 55% of participants (6/11) and at molecular weights of ≈30, ≈40 and ≈70 kDa in 45% (5/11) compared with the first study visit. Nitrophorin and apyrase were the most common C lectularius proteins identified with liquid chromatography-tandem mass spectrometry in both crushed bed bug salivary gland extract and post-bed bug feeding extract.

CONCLUSIONS

Human participants did not have consistent IgG responses to crushed C lectularius salivary gland extract.

A Method for Evaluating Insecticide Efficacy against Bed Bug, Cimex lectularius, Eggs and First Instars

Standard toxicity evaluations of insecticides against insect pests are primarily conducted on adult insects. Evaluations are based on a dose-response or concentration-response curve, where mortality increases as the dose or concentration of an insecticide is increased. Standard lethal concentration (LC50) and lethal dose (LD50) tests that result in 50% mortality of a test population can be challenging for evaluating toxicity of insecticides against non-adult insect life stages, such as eggs and early instar or nymphal stages. However, this information is essential for understanding insecticide efficacy in all bed bug life stages, which affects control and treatment efforts. This protocol uses a standard dipping bioassay modified for bed bug eggs and a contact insecticidal assay for treating nymphal first instars. These assays produce a concentration-response curve to further quantify LC50 values for insecticide evaluations.

Bullous scabies: a case report and review of the literature

Background

Scabies is a common parasitic infection caused by the mite Sarcoptes Scabiei. About 300 million cases of scabies are reported annually. Scabies usually presents clinically with an erythematous excoriated papulovesicular rash, burrows, nodules and hyperkeratotic lesions in specific body areas.

A rare presentation of scabies is the bullous pemphigoid-like bullous scabies. So far, to the best of our knowledge, only 32 cases of bullous scabies have been reported in medical literature, of which only 11 were under 60 years of age at the time of initial presentation. This is the first case of bullous scabies being reported from Pakistan.

Case presentation

Herein we discuss, with reference to the existing literature, the case of a 23-year-old Punjabi male who presented with a 3 day history of a tense, non-erythematous, non-tender bulla measuring approximately 0.5 cm x 0.8 cm on the right foot near the interdigital cleft. He was diagnosed to have bullous scabies.

Conclusion

The diagnosis of scabies should be considered in all patients who present with tense bullous lesions accompanied by pruritus and a maculopapular rash. This is particularly relevant if these lesions do not resolve with steroid treatment. In such patients, in order to prevent a misdiagnosis of bullous pemphigoid, scrapings for Sarcoptes Scabiei mites and eggs should be taken.

[Cockroaches and co. The role of health pests as allergen source]

In most of the cases health pests are carriers of pathogens or parasites which have a negative impact on human health or affect the health of other mammals. What is lesser known is that they can also act as allergens. Most of the health pests in this sense belong to the arthropods, such as cockroaches (Blattaria), mosquitos (Culiciformia), lice (Pediculus humanus corporis), fleas (Siphonaptera) and ticks (Argasidae). In the group of vertebrates rats (Rattus norvegicus and Rattus rattus), house mice (Mus musculus) and pigeons (Columba livia domestica) are also classified as health pests. Also storage pests which are not carriers of pathogens can induce secondary infestation with hygiene pests or molds and have an underestimated impact on human health. In this article selected examples of health pests and also storage pests as an allergen source are described, taking into account the sensitization prevalence and identified single allergens.

Insecticide Resistance in Eggs and First Instars of the Bed Bug, Cimex lectularius (Hemiptera: Cimicidae)

Two strains of the common bed bug, Cimex lectularius L., eggs and first instars collected from pyrethroid-resistant adults were evaluated for insecticide resistance and compared to a susceptible strain. Dose-response bioassays were conducted using two insecticide formulations (Temprid: imidacloprid/β-cyfluthrin, and Transport: acetamiprid/bifenthrin). The lethal concentration (LC₅₀) for the two resistant egg strains exposed to imidacloprid/β-cyfluthrin ranged from 3 to 5-fold higher than susceptible strain eggs. Resistant strain eggs dipped into formulations of acetamiprid/bifenthrin had LC₅₀ values which were significantly greater (39 to 1,080-fold) than susceptible strain eggs. Similar to eggs, resistant strain first instars exposed to residual applications of imidacloprid/β-cyfluthrin had LC₅₀ values ranging from 121 to 493-fold greater than susceptible strain first instars. When resistant strain first instars were treated with acetamiprid/bifenthrin, they had LC₅₀ values that were 99 to >1,900-fold greater than susceptible strain first instars. To determine differences between egg and first instar resistance, stage resistance ratios (SRR) were compared between the two stages. There was little difference between the egg and first instar stages, indicated by small SRR values ranging from 1.1 to 10.0. This study suggests that insecticide resistance is expressed early during bed bug development.

Bed bug detection: current technologies and future directions

Technologies to detect bed bugs have not kept pace with their global resurgence. Early detection is critical to prevent infestations from spreading. Detection based exclusively on bites is inadequate, because reactions to insect bites are non-specific and often misdiagnosed. Visual inspections are commonly used and depend on identifying live bugs, exuviae, or fecal droplets. Visual inspections are inexpensive, but they are time-consuming and unreliable when only a few bugs are present. Use of a dog to detect bed bugs is gaining in popularity, but it can be expensive, may unintentionally advertise a bed bug problem, and is not foolproof. Passive monitors mimic natural harborages; they are discreet and typically use an adhesive to trap bugs. Active monitors generate carbon dioxide, heat, a pheromone, or a combination to attract bed bugs to a trap. New technologies using DNA analysis, mass spectrometry, and electronic noses are innovative but impractical and expensive for widespread use.

Bed bugs reproductive life cycle in the clothes of a patient suffering from Alzheimer's disease results in iron deficiency anemia

We report the case of an 82-year-old patient, hospitalized for malaise. Her clothes were infested by numerous insects and the entomological analysis identified them as being Cimex lectularius (bed bugs). The history of the patient highlighted severe cognitive impairment. The biological assessment initially showed a profound microcytic, aregenerative, iron deficiency anemia. A vitamin B12 deficiency due to pernicious anemia (positive intrinsic factor antibodies) was also highlighted, but this was not enough to explain the anemia without macrocytosis. Laboratory tests, endoscopy and a CT scan eliminated a tumor etiology responsible for occult bleeding. The patient had a mild itchy rash which was linked to the massive colonization by the bed bugs. The C. lectularius bite is most often considered benign because it is not a vector of infectious agents. Far from trivial, a massive human colonization by bed bugs may cause such a hematic depletion that severe microcytic anemia may result.

Application of native prick test in diagnosis of bed bug allergy

The aim of the study was case report of the patient with systemic reaction after a bed bug (Cimex lectularius) bite. A 23-year-old female, previously healthy, reports systemic reaction, including rash on her corpus and limbs, itching, nausea, conciseness disorder, forcing her to call the ambulance. The interview revealed that the bed bug occurs in the patient's apartment. A prick-by-prick test with bed bug excretion was made. The skin test with native allergen was strongly positive (histamine 5 mm/5 mm, prick-by-prick 12 mm/8 mm). The prick-by-prick test was useful in objective confirmation of the source of symptoms.

Bugging forecast: unknown, disliked, occasionally intimate. Bed bugs in Germany meet unprepared people

Bed bugs appear to be feared more than vector insects and other household pests. The reasons for this exaggerated fear are not fully understood. One hypothesis is that the folk knowledge on recognising and controlling bed bugs decreased as bed bugs became rarer in the 1960s and led to irrational perceptions. Here, we examine people’s ability to recognise a bed bug and their response what to do in case of an infestation. We found that 13% of a sample of 391 people in four large German cities recognised a bed bug; 15% of all respondents would call a pest controller in case of bed bug infestation. This results in the pessimistic estimate that 97% of all early-stage infestations could go untreated. We discuss additional scenarios. The effectiveness of efforts to educate people about the presence of bed bugs has never been tested, but our sample is useful to guide future studies. We found three sources of information were associated with increased recognition rates of bed bugs: a) previous contacts with bed bugs (60% recognition), b) knowledge from friends or relatives (25%) and school or education courses (15%). By contrast, people who heard of bed bugs from television, print media or the Internet showed reduced recognition rates. We propose that the former factors be tested for educational interventions. In Germany, the bed bug is an estranged creature to many people, a fact that seems to hinder rational approaches to their control.

IgG/IgE bullous pemphigoid with CD45 lymphocytic reactivity to dermal blood vessels, nerves and eccrine sweat glands

CONTEXT

Bullous pemphigoid (BP), the most common autoimmune blistering disease, is mediated by autoantibodies. BP primarily affects the elderly and is characterized by the development of urticarial plaques surmounted by subepidermal blisters, and the deposition of immunoglobulins and complement at the basement membrane zone (BMZ) of the skin. BP is immunologically characterized by the development of autoantibodies targeting two structural proteins of the hemidesmosomes, BP180 (collagen XVII) and BP230 (BPAG1).

CASE REPORT

A 63 -year-old Caucasian female patient was evaluated for a 4 day history of several itching, erythematous blisters on her extremities. Biopsies for hematoxylin and eosin (H&E) examination, as well as Periodic acid-Schiff (PAS), immunohistochemistry (IHC) and direct immunofluorescence (DIF) analysis were performed.

RESULTS

H&E demonstrated a subepidermal blister, with partial re-epithelialization of the blister floor. Within the blister lumen, numerous neutrophils were present, with occasional eosinophils and lymphocytes also noted. Within the dermis, a mild, superficial, perivascular and periadnexal infiltrate of lymphocytes, histiocytes and occasional eosinophils was identified, with mild perivascular leukocytoclastic debris. The PAS stain was positive at the BMZ, and around selected blood vessels, nerves and sweat glands. DIF revealed linear deposits of IgG and Complement/C3 and fibrinogen at the BMZ, and around selected dermal nerves, blood vessels and sweat glands. Strong granular deposits of IgE were also observed, colocalizing with monoclonal antibodies to Collagen IV (CIV). By IHC, positive CD45 staining of lymphocytes was seen surrounding selected dermal blood vessels, eccrine sweat glands, and nerves.

CONCLUSION

The patient displayed IgG, IgE, and fibrinogen autoantibodies against the BMZ, as well as around some dermal nerves and sweat glands; their binding in the skin could trigger complement activation. In addition, the role of the dermal CD45 positive lymphocytes warrants further investigation.

Bullous reactions to bedbug bites reflect cutaneous vasculitis

BACKGROUND

There has been a worldwide resurgence of bedbug infestations. Bites by these insects may cause mild or severe cutaneous reactions, and anaphylaxis has been reported. Little is known about the most severe cutaneous reactions, termed bullous or complex reactions.

OBJECTIVE

To study the time course and histopathologic findings of complex (bullous) cutaneous reactions to bedbugs in order to determine the optional treatment for them.

DESIGN, SETTING, AND PARTICIPANTS

We prospectively photographed bullous reactions to observed bedbug bites at 30 minutes; 6, 12, 24, 36, 48, and 72 hours; 1, 2, 3, and 4 weeks, and biopsied reactions at 30 minutes, and 6, 12, and 24 hours. We also reviewed Internet postings and the available medical literature on bullous reactions after bedbug bites.

MAIN OUTCOMES AND MEASURES

Correlations between clinical and histologic findings using both routine and immunofluorescent techniques.

RESULTS

Bullous reactions to bedbugs are not rare. Of 357 photographs of bedbug bites posted on the Internet, 6% were bullous. In an individual with previous bullous reactions, experimental bedbug bites were associated with a progression of cutaneous responses at bite sites from immediate, pruritic, edematous lesions to a late-in-time macule, which evolved into bullous reactions by 24 hours. Bullous lesions eventually lysed but took weeks to heal. Histopathologic evaluation of bullous reactions showed a polymorphous picture with histologic evidence of an urticarial-like reaction early on that rapidly developed into a hybrid leukocytoclastic vasculitis. This vasculitis was initially neutrophilic but developed into a destructive, necrotizing, eosinophil-rich vasculitis with prominent infiltration of CD 68+ histiocytes and collagen necrobiosis. This histologic picture is similar to the dermal vasculitis in patients with Churg-Strauss vasculitis.

CONCLUSION

Historically, bedbug bite reactions have been considered to be of minor medical significance. However, the findings presented here demonstrate that the not-uncommon bullous reactions to bedbug bites reflect the presence of a local, highly destructive, cutaneous vasculitis. The histologic features of these reactions resemble those occurring in the Churg-Strauss syndrome. Therefore, efforts to prevent further bites and monitor for evidence of systemic vasculitis should be made in patients with bullous reactions to bedbug bites. Topical treatment with high potency corticosteroids may be useful in the treatment of bullous reactions.

Bed bugs: clinical relevance and control options

Since the late 1990s, bed bugs of the species Cimex lectularius and Cimex hemipterus have undergone a worldwide resurgence. These bed bugs are blood-sucking insects that readily bite humans. Cutaneous reactions may occur and can start out as small macular lesions that can develop into distinctive wheals of around 5 cm in diameter, which are accompanied by intense itching. Occasionally, bullous eruptions may result. If bed bugs are numerous, the patient can present with widespread urticaria or eythematous rashes. Often, bites occur in lines along the limbs. Over 40 pathogens have been detected in bed bugs, but there is no definitive evidence that they transmit any disease-causing organisms to humans. Anemia may result when bed bugs are numerous, and their allergens can trigger asthmatic reactions. The misuse of chemicals and other technologies for controlling bed bugs has the potential to have a deleterious impact on human health, while the insect itself can be the cause of significant psychological trauma. The control of bed bugs is challenging and should encompass a multidisciplinary approach utilizing nonchemical means of control and the judicious use of insecticides. For accommodation providers, risk management procedures should be implemented to reduce the potential of bed bug infestations.

Insect stings: clinical features and management

BACKGROUND

In human beings, local and systemic reactions can be caused both by blood-sucking insects and by venomous insect stings. In Central Europe, the insects that most commonly cause such reactions are honeybees, certain social wasps, mosquitoes, and flies.

METHODS

This article is based on a selective literature review, including guidelines from Germany and abroad.

RESULTS

Insect venom induces a toxic reaction at the site of the sting. Large local reactions are due to allergy and occur in up to 25% of the population; as many as 3.5% develop IgE-mediated, potentially life-threatening anaphylaxis, of which about 20 people die in Germany each year. Mastocytosis is found in 3% to 5% of patients with sting anaphylaxis, rendering these patients prone to very severe reactions. Blood-sucking by hematophagous insects can elicit a local allergic reaction, presenting as a wheal or papule, in at least 75% of the population. Large local reactions may ensue, but other diseases are rare. The acute symptoms of an insect sting are treated symptomatically. Patients who have had a systemic reaction or a large local reaction due to insect allergy must take permanent measures to avoid further allergen contact, and to make sure they can treat themselves adequately if stung again. Most patients with systemic anaphylactic reactions to bee or wasp stings need specific immunotherapy.

CONCLUSION

Insect stings can cause severe disease. Anaphylaxis due to bee or wasp stings is not a rare event; specific immunotherapy protects susceptible persons from further, potentially life-threatening reactions.

Bedbugs (Cimicidae infestation): the worldwide renaissance of an old partner of human kind

Bedbugs have been known as a human parasite for thousands of years, but scientific studies about this insect are recent and limited. Cimex lectularius, the common bedbug, was a well-known parasite in human dwellings until the end of the Second World War. Nowadays, bedbugs are considered uncommon in the industrialized world. Anecdotal reports suggest that bedbugs are getting more common in the United States, Canada, and United Kingdom. In Brazil, there are few reports about bedbug infestations in the literature. The aim of this article was to alert physicians, especially in Brazil, about this ectoparasitosis, including aspects of the bedbug biology, their parasitism in human host, treatment and prophylaxis.

Stress Tolerance of Bed Bugs: A Review of Factors That Cause Trauma to Cimex lectularius and C. Hemipterus

Recent emergence of bed bugs (Cimex spp.) has prompted a significant expansion of research devoted to this pest. The ability to survive and recover from stress has significant implications on the distribution and survival of insects, and bed bugs are no exception. Research on bed bug stress tolerance has shown considerable progress and necessitates a review on this topic. Bed bugs have an extraordinary ability to resist dehydration between bloodmeals, and this represents a critical factor allowing their prolonged survival when no host is available. High relative humidities are detrimental to bed bugs, leading to reduced survival in comparison to those held at lower relative humidities. Continual exposure of bed bugs, eggs and mobile stages, to temperatures below freezing and short term exposure (=1 h) to temperatures below -16 to -18 °C results in mortality. The upper thermal limit for short term exposure of eggs, nymphs and adults is between 40-45 °C for the common (Cimex lectularius) and tropical (C. hemipterus) bed bugs. Long-term exposure to temperatures above 35 °C results in significant reduction in survival of mobile bed bugs. Eggs for C. lectularius and C. hemipterus are no longer viable when held below 10 °C or above 37 °C throughout embryogenesis. Blood feeding, although necessary for survival and reproduction, is discussed as a stress due to thermal and osmotic fluctuations that result from ingesting a warm bloodmeal from a vertebrate host. Cold, heat, water stress and blood feeding prompted the expression of heat shock proteins (Hsps). Pesticide application is a common human-induced stress for urban pests, and recent studies have documented pesticide resistance in many bed bug populations. High levels of traumatic insemination (mating) of bed bugs has been linked to reduced survival and fecundity along with possibly exposing individuals to microbial infections after cuticular penetration by the paramere (=male reproductive organ), thus represents a form of sexual stress. Additionally, less common stress types such as microbial infections that have been documented in bed bugs will be discussed. Overall, this review provides a current update of research related to bed bug stress tolerance and how their ability to resist stressful conditions has lead to their expansion and proliferation.

Cellular FLICE-inhibitory protein (cFLIP) isoforms block CD95- and TRAIL death receptor-induced gene induction irrespective of processing of caspase-8 or cFLIP in the death-inducing signaling complex

Death receptors (DRs) induce apoptosis but also stimulate proinflammatory "non-apoptotic" signaling (e.g. NF-κB and mitogen-activated protein kinase (MAPK) activation) and inhibit distinct steps of DR-activated maturation of procaspase-8. To examine whether isoforms of cellular FLIP (cFLIP) or its cleavage products differentially regulate DR signaling, we established HaCaT cells expressing cFLIP(S), cFLIP(L), or mutants of cFLIP(L) (cFLIP(D376N) and cFLIP(p43)). cFLIP variants blocked TRAIL- and CD95L-induced apoptosis, but the cleavage pattern of caspase-8 in the death inducing signaling complex was different: cFLIP(L) induced processing of caspase-8 to the p43/41 fragments irrespective of cFLIP cleavage. cFLIP(S) or cFLIP(p43) blocked procaspase-8 cleavage. Analyzing non-apoptotic signaling pathways, we found that TRAIL and CD95L activate JNK and p38 within 15 min. cFLIP variants and different caspase inhibitors blocked late death ligand-induced JNK or p38 MAPK activation suggesting that these responses are secondary to cell death. cFLIP isoforms/mutants also blocked death ligand-mediated gene induction of CXCL-8 (IL-8). Knockdown of caspase-8 fully suppressed apoptotic and non-apoptotic signaling. Knockdown of cFLIP isoforms in primary human keratinocytes enhanced CD95L- and TRAIL-induced NF-κB activation, and JNK and p38 activation, underscoring the regulatory role of cFLIP for these DR-mediated signals. Whereas the presence of caspase-8 is critical for apoptotic and non-apoptotic signaling, cFLIP isoforms are potent inhibitors of TRAIL- and CD95L-induced apoptosis, NF-κB activation, and the late JNK and p38 MAPK activation. cFLIP-mediated inhibition of CD95 and TRAIL DR could be of crucial importance during keratinocyte skin carcinogenesis and for the activation of innate and/or adaptive immune responses triggered by DR activation in the skin.

Transcriptomics of the bed bug (Cimex lectularius)

BACKGROUND

Bed bugs (Cimex lectularius) are blood-feeding insects poised to become one of the major pests in households throughout the United States. Resistance of C. lectularius to insecticides/pesticides is one factor thought to be involved in its sudden resurgence. Despite its high-impact status, scant knowledge exists at the genomic level for C. lectularius. Hence, we subjected the C. lectularius transcriptome to 454 pyrosequencing in order to identify potential genes involved in pesticide resistance.

METHODOLOGY AND PRINCIPAL FINDINGS

Using 454 pyrosequencing, we obtained a total of 216,419 reads with 79,596,412 bp, which were assembled into 35,646 expressed sequence tags (3902 contigs and 31744 singletons). Nearly 85.9% of the C. lectularius sequences showed similarity to insect sequences, but 44.8% of the deduced proteins of C. lectularius did not show similarity with sequences in the GenBank non-redundant database. KEGG analysis revealed putative members of several detoxification pathways involved in pesticide resistance. Lamprin domains, Protein Kinase domains, Protein Tyrosine Kinase domains and cytochrome P450 domains were among the top Pfam domains predicted for the C. lectularius sequences. An initial assessment of putative defense genes, including a cytochrome P450 and a glutathione-S-transferase (GST), revealed high transcript levels for the cytochrome P450 (CYP9) in pesticide-exposed versus pesticide-susceptible C. lectularius populations. A significant number of single nucleotide polymorphisms (296) and microsatellite loci (370) were predicted in the C. lectularius sequences. Furthermore, 59 putative sequences of Wolbachia were retrieved from the database.

CONCLUSIONS

To our knowledge this is the first study to elucidate the genetic makeup of C. lectularius. This pyrosequencing effort provides clues to the identification of potential detoxification genes involved in pesticide resistance of C. lectularius and lays the foundation for future functional genomics studies.

Insight into the Sialome of the Bed Bug, Cimex lectularius

The evolution of insects to a blood diet leads to the development of a saliva that antagonizes their hosts' hemostasis and inflammation. Hemostasis and inflammation are redundant processes, and thus a complex salivary potion composed of dozens or near 100 different polypeptides is commonly found by transcriptome or proteome analysis of these organisms. Several insect orders or families evolved independently to hematophagy, creating unique salivary potions in the form of novel pharmacological use of endogenous substances and in the form of unique proteins not matching other known proteins, these probably arriving by fast evolution of salivary proteins as they evade their hosts' immune response. In this work we present a preliminary description of the sialome (from the Greek Sialo = saliva) of the common bed bug Cimex lectularius, the first such work from a member of the Cimicidae family. This manuscript is a guide for the supplemental database files http://exon.niaid.nih.gov/transcriptome/C_lectularius/S1/Cimex-S1.zip and http://exon.niaid.nih.gov/transcriptome/C_lectularius/S2/Cimex-S2.xls.

Resurgence of bedbugs in southern France: a local problem or the tip of the iceberg?

BACKGROUND

Bedbugs (Cimex lectularius) have been feeding on sleeping human beings since prehistory. In Europe, bed bugs were common and endemic until World War II when improved body and home hygiene, and widespread use of insecticides led to almost complete eradication. Current evidence indicates that bedbugs are making a comeback in Europe, USA, Canada and Australia. In our practice in Southern France, we observed several cases within a period of only 1 year.

OBJECTIVES

Based on this experience, we conducted an epidemiological study to evaluate the status of bedbugs in France.

METHODS

During summer 2009, we mailed a short questionnaire to all hospital professors in the CEDEF (Collège des Enseignants de Dermatologie de France) asking four questions: number of suspected diagnosis of bedbugs in the year 2009, and number of certain positive diagnosis, difficulties in treatment, use of a pest control professional for treatment, and finally personal opinion on actual incidence of bedbugs, compared with past years.

RESULTS

Of the 84 questionnaires sent, there were only 26 responses despite two reminders. The responses were predominantly southern France, probably as a result of intensive immigration and increased travel and trade. Difficulties encountered during diagnosis and treatment are also mentioned. Utilizing the services of entomological experts and pest control professionals is essential.

CONCLUSIONS

  France has the same experience regarding the resurgence of bedbugs as several European countries, USA, Canada and Australia, especially the southern regions. This emerging health problem has to be known by dermatologists. A national programme has been launched in France to assess actual incidence and study C. lectularius- related diseases.

4-oxo-aldehydes from the dorsal abdominal glands of the bed bug (Hemiptera: Cimicidae)

Analyses of the dorsal abdominal glands of fourth- and fifth-instar nymphs of the bed bud, Cimex lectularius L. (Hemiptera: Cimicidae), indicated the predominant constituents were (E)-2-hexenal and (E)-2-octenal, with lesser amounts of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal. The latter two compounds have not been reported previously as occurring in bed bugs. There were no differences in the chemical composition of the dorsal abdominal glands excised from exuviae left behind by either male or female adults, nor from glands excised from fourth-instar exuviae. Because the two oxo-aldehydes made up at least 16% of the gland contents, further study of the functional role of these chemicals seem advisable.

Bedbugs

Cimex lectularius (the "bedbug") is an insect that feeds nocturnally, taking a requisite blood meal from a sleeping human or other parasitized host. Immunological reactions to bedbug saliva vary, but typically, bites yield erythematous and pruritic papules. The face and distal extremities, areas uncovered by sleeping clothes or blankets, are preferentially involved. Until the late 1990s, bedbug infestations in the United States were declining. Resurgence is attributed to increased travel and resistance to insecticides. Although hepatitis or human immunodeficiency virus is not effectively transmitted by the bedbug, pruritus and the fear and perceived violation of an infestation can be debilitating. Bedbugs are small but robust, and their ability to remain ensconced in crevices within the bedroom makes eradication difficult. As more patients present with bedbug bites, physicians must possess the knowledge to diagnose, treat, and educate with regard to bedbug bites and bedbug infestations.

Structural biology of allergens from stinging and biting insects

PURPOSE OF REVIEW

Modern techniques in genomic and protein research are applied to the study of stinging and biting insect allergens.

RECENT FINDINGS

Three-dimensional structures of additional insect venom and salivary allergens have been determined. An approach to determining B-cell epitopes has been used for hyaluronidase. A number of new venom and salivary allergens have been characterized. The structures and significance of several insect allergens have been updated. Investigations continue into distinguishing venom crossreactivity from multiple sensitization. Further studies are clarifying the significance of carbohydrate epitopes. Genomic and proteomic techniques are being used in the investigation of proteins and peptides in insect venom and saliva.

SUMMARY

The nature of venom crossreactivity and the B-cell and T-cell epitope structures of insect venom and salivary allergens are beginning to be elucidated.

Sensitivity to bites by the bedbug, Cimex lectularius

Bedbugs are a public health problem and can cause significant economic losses, but little is known about the effects of bites on humans. We reviewed case reports and published papers on bedbug bites to assess the empirical basis of the commonly cited figure that only approximately 80% of the population are sensitive to bedbug bites. We found the sensitivity estimate to be based on only one study carried out 80 years ago. However, this study did not account for the now well-established fact that only repeated exposure to external allergens leads to skin reactions. In our sample, 18 of 19 persons showed a skin reaction after bedbug exposure, but in most cases only after repeated controlled exposure. With repeated exposure, the latency between bite and skin reactions decreased from approximately 10 days to a few seconds. Our results are relevant for the hospitality industry, where apparently increasing infestation rates are likely to lead to an increase in the number of tourists and hotel employees exposed to bedbugs. Medical and public health professionals may expect to see an increase in the prevalence of people with bedbug bite sensitivity. The significance of the delayed reaction time of skin to bites may also have implications in litigation cases where people seek compensation.

Off-host aggregation behavior and sensory basis of arrestment by Cimex lectularius (Heteroptera: Cimicidae)

The bed bug, Cimex lectularius, aggregates under filter paper disks previously stained by adults. A multiple choice assay was used to determine differences in aggregation behavior among two strains, multiple lifestages, and levels of starvation. There were no differences in level of aggregation between established and recently derived strains, or among adults and nymphs of different instars. Propensity to aggregate decreased with time since feeding, but preference for stained disks remained high. We also examined which sensory structures mediate aggregation, and whether antennectomy affected movement, orientation, and arrestment under stained disks. Bed bugs that were left intact, blinded, or surgically altered by the removal of probosci or the distal antennal segments exhibited high levels of aggregation under stained disks. However, the removal of the pedicel significantly reduced aggregation compared to intact bugs. Video recordings of movement and orientation by bugs with intact, partial and complete antennectomies demonstrated that neither partial nor complete antennectomies affected walking speed, path straightness, direction of movement or frequency of encounters with either stained or clean disks. However, complete removal of both antennae significantly reduced the percentage of encounters with stained disks that resulted in arrestment. These findings suggest aggregation by bed bugs is a result of arrestment mediated by direct, close-range contact between sensilla on the pedicel and stained disks.

Human anti-saliva immune response following experimental exposure to the visceral leishmaniasis vector, Lutzomyia longipalpis

Experiments in animals verified that phlebotomine saliva enhances Leishmania infection, and vaccination with saliva prevents disease. We have shown that individuals from an endemic area of visceral leishmaniasis displayed robust antibody responses to saliva from the vector Lutzomyia longipalpis, which correlated with anti-parasite cell-mediated immunity. Here, we explored human anti-saliva responses following exposure to sand flies, using an in vivo bite model in which normal volunteers were exposed four times to 30 laboratory-reared Lu. longipalpis. Following the third exposure, normal volunteers developed diverse dermatological reactions at the site of insect bite. Serum from normal volunteers displayed high levels of anti-salivary gland sonicate IgG1, IgG4 and IgE as well as several salivary gland proteins. Furthermore, following in vitro stimulation with salivary gland sonicate, there was an increased frequency of CD4(+)CD25(+) and CD8(+)CD25(+) T cells as well as IFN-gamma and IL-10 synthesis. Strikingly, 1 year after the first exposure, PBMC from the volunteers displayed recall IFN-gamma responses that correlated with a significant reduction in infection rates using a macrophage-lymphocyte autologous culture. Together, these data suggest that human immunization against sand fly saliva is feasible and recall responses are obtained even 1 year after exposure, opening perspectives for vaccination in man.

Bedbug infestations recorded in Central Italy

In summer 2003 two separate infestations due to the common bedbug (Cimex lectularius) occurred in Pisa, Italy. Cutaneous reaction was evident and one patient developed a severe bullous eruption. In both cases there was circumstantial evidence for association with international travel.