Arthropod assaults on humans can have many manifestations clinically, histologically, and immunologically. Hemiptera is an order of insect species of "true bugs" that has piercing-sucking mouthparts and includes the family Cimicidae (bedbugs), which are blood-sucking ectoparasites of mammals or birds.
All Cimex species organisms are reddish brown insects. Cimex lectularius is 5-7 mm in size, with the females slightly larger than the males. Cimex hemipterus organisms are approximately 25% longer than C lectularius organisms. Females deposit fertilized eggs in cracks or crevices, with newborns emerging in 4-5 days. Note the images below.
View Image | The bedbug is a flat, oval, reddish brown insect that turns violaceous after feeding. Courtesy of Colonel Dirk M. Elston, MD (from Elston, 2000). |
View Image | Bedbugs are parasitic arthropods from the family Cimicidae. They are typically less than 1 cm in length and reddish brown in color. Bedbugs can be fou.... |
See When Bugs Feast: What's Causing that Itch?, a Critical Images slideshow, to help identify various skin reactions, recognize potential comorbidities, and select treatment options.
Bedbug infestations seem to be increasing around the world at an alarming rate, possibly due to insecticide resistance.[1] Resistance to pyrethroid insecticides is already widespread in the United States. The bedbug occurs in aggregations when conditions are favorable, but the arthropods disperse when conditions are unfavorable.[2] Active female dispersal can potentially lead to treatment failures and should be taken into account when using control methods.
New tactics may be needed for this escalating public health concern in locations with high occupant turnover, such as hotels, hospitals, and nursing homes.[3] Indeed, in the past decade bedbugs have become a worldwide urban pest, with the number of American households affected markedly increased.[4] Genetic data suggest that C lectularius may be undergoing lineage divergence through host association.[5]
Bedbugs have two barriers with distinct temperature-sensitive and lipid-based physicochemical properties to protect them against insecticides.[6] More research on the bedbug is desirable, including use of autofluorescence lifetime measurements to analyze the bedbug arthropod cuticle.[7]
The tropical bedbug (Cimex hemipterus) has reappeared in Florida after nearly 60 years[8] and has been described in Italy.[9] C hemipterus is behaviorally and biologically similar to C lectularius. How this particular type of bedbug was reintroduced is unknown, and more research is needed to determine its distribution and how established it is.
The mechanism of skin injury by arthropods depends on the structure of the mouthparts. These insects are categorized as vessel feeders if they insert the tip into a capillary or as pool feeders if they feed on the extravasated blood from damaged tissue. They often inject different pharmacologically active substances (eg, hyaluronidase, proteases, kinins), which may cause different skin reactions (eg, erythema, wheal, vesicle, hemorrhagic nodule). See the following images.
View Image | Bedbugs feeding on a human host. Courtesy of Colonel Dirk M. Elston, MD (from Elston, 2000). |
View Image | After bedbugs find a food source, they bite down with their mouths and inject anticoagulant and anesthetic compounds into the skin. Depending on the s.... |
The type of reaction provoked depends on previous exposure; repeated bites may lead to an allergic reaction, which may lead to pronounced cutaneous manifestations. Some patients show a severe systemic hypersensitivity to arthropod allergens. The site of the bite can also become secondarily infected with bacteria infection and lead to ecthyma, cellulitis, and/or lymphangitis.
See the image below.
View Image | Bedbug bites themselves are typically painless. However, the subsequent allergic reaction that may develop can cause intense pruritus. While feeding, .... |
Thus, although these insects usually cause mild cutaneous reactions, more severe responses, including anaphylaxis, may occur.[10] Bullae may be noted. Skin responses at bite sites may evolve from immediate, pruritic, edematous macules into bullae within 24 hours. Histopathologically, an urticarial-like reaction can develop into a leukocytoclastic vasculitis, sometimes with a destructive, necrotizing, eosinophil-rich vasculitis with prominent infiltration of CD68+ histiocytes and collagen necrobiosis.
Insect bites, including those from the bedbug, have been proposed as a factor contributing to the formation of a cutaneous reaction termed papular urticaria. Patients with papular urticaria have been shown to demonstrate immunoglobulin (Ig) G antibodies to bedbug (C lectularius) antigens.[11] Thus, IgG against C lectularius, Cimex pipiens, and Pulex irritans in patients with papular urticaria may contribute the pathogenesis of this condition.
Susceptibility to arthropod bites depends on many external factors, such as occupation, conditions of employment, cohabitation with a variety of domestic animals, housing, climate, and clothing. An arthropod is usually attracted to its host by body heat, carbon dioxide in exhaled air, vibration, human sweat, and/or odor. The Cimex (bedbug) genus attacks both mammals and birds. C hemipterus (the tropical bedbug) bites mostly humans and is found in warm climates, whereas C lectularius (the common bedbug) also attacks bats and domestic animals, such as chickens.
Bedbugs are 5-7 mm in length with reduced wings and modified mouthparts for piercing and sucking. These insects live between wooden floorboards, in furniture, in bed frames, in mattresses, or behind peeling paint. Bedbugs sneak out to grasp human skin with their forelegs, pierce the skin, and inject anticoagulant- and anesthetic-containing saliva.
Bedbugs normally feed at night, usually approximately 1 hour before dawn. However, if the conditions are favorable, they also feed during the day. Feeding takes 3-12 minutes. In proper conditions, adult bedbugs can survive without a meal for 1 year or longer. Each female lays approximately 300 eggs in her lifetime. The eggs hatch in 10 days. The nymph stage lasts 6 weeks, undergoing 5 molts.
Bedbugs can be seen anywhere, but they tend to occur in environments in disarray. Old furniture makes an excellent home for bedbugs. These insects also like to hide in the seams and folds of mattresses and in bed frames and springs.
Passenger ships provide conditions suitable for the survival and growth of many pest populations. In a 2008 study, pest infestations were identified in 21 ferries: 18 with flies, 11 with cockroaches, and with 3 with bedbugs.[12]
Bedbug infestations affect both sexes and people of all ages and races in the United States and globally, particularly in poor regions of the world.[13] The reported rate of bedbugs (Cimex hemipterus) was 37.5% in children's beds from a rural region of Gambia. Recently, bedbugs were allegedly reintroduced from abroad into Seoul, Korea, because there had been no reports on bedbugs in Seoul for more than 20 years.[14]
The prognosis for bedbug bites is excellent, although these bites can create considerable anxiety and localized and occasionally systemic reactions. Sometimes, if the bite reactions are intensely pruritic, scratching with excoriations may be complicated by impetigo.
In addition, bedbugs may be a vector for hepatitis B[15] and, in endemic areas, for American trypanosomiasis (Chagas disease).[16, 17] Of note, reports have indicated the risk of insect transmission of human immunodeficiency virus (HIV), if any, is extremely low and likely nonexistent.[18, 19]
Anaphylactoid reactions are well described. One such case occurred in a 41-year-old businessman in a first-class urban hotel in the United States.
Educate the patient and family about bedbugs and their habits. Patients should avoid scratching the bite sites to reduce local irritation and prevent secondary infection. See also Prevention of Bedbug Bites.
For patient education information, see Allergies Center as well as Insect Bites and Severe Allergic Reaction (Anaphylactic Shock).
Bedbug bites often occur at night, because the insects are nocturnal, with peak activity just before dawn. Bedbugs are resourceful and opportunistic. In a well-documented daytime outbreak, its victims were all women who rode a particular English tram.[20] Each woman had a peculiar band of erythema studded with bullae on the back of both calves.
Repeated exposure to external bedbug bites leads to skin reactions. In 2009 report, 18 of 19 persons had a skin reaction after bedbug exposure, but usually only after repeated controlled exposure.[21] With repeated exposure, the latency between the bite and the skin reaction decreased from about 10 days to a few seconds.[21]
Visually searching beds for bedbugs may be useful.[22] It may be more efficient to survey the corners of bed nets and mattresses. These insects also produce a peculiar pungent odor familiar to building inspectors and tenement dwellers. With a heavy infestation, specklike masses of dung may be evident behind wallpaper and at other sites. This dung contains blood elements.[22] They may adapt to the corporate office workplace.[23] Bedbugs residing under an abnormal human nail plate thickened by marked subungual hyperkeratosis has been described, which is most unusual, as they do not usually live on the host.[24]
As reported by Leibold et al,[25] a disseminated bullous eruption with systemic reaction caused by C lectularius may occur, but this is rare.
Most commonly, exposed skin is affected. Bedbug bites are painless, but pruritus and purpuric macules may appear. Their distribution depends on the bite site, whether it be the face, neck, hands, arms, lower legs, or generalized; however, they often are evident on the face upon awakening in the morning.
Papules, urticaria, or bullae may predominate together with signs of secondary infection. The bullae are rarely severe.[26] A hemorrhagic puncta may be evident. If a person is not sensitized, no symptoms may be evident, only a purpuric macule at the bite site. Targetoid and edematous plaques may be evident, mandating distinction from erythema multiforme and Sweet syndrome.[27]
Bites are often noted in linear groups of 3, sometimes called "breakfast, lunch, and dinner," evident as erythematous papules, sometimes with a prominent urticarial component in predisposed individuals.
Note the images below.
View Image | Bedbugs feeding on a human host. Courtesy of Colonel Dirk M. Elston, MD (from Elston, 2000). |
View Image | Bedbug bites themselves are typically painless. However, the subsequent allergic reaction that may develop can cause intense pruritus. While feeding, .... |
Go to Papular Urticaria and Acute Urticaria for complete information on these topics.
Consider appropriate laboratory studies in the context of the clinical picture. Bedbug bites seldom require laboratory tests.
Most reactions to bedbugs show a superficial and deep perivascular mixed inflammatory infiltrate, with eosinophils being prominent rather than neutrophils. Eosinophils may be prominent among collagen bundles, or they may be absent.
Medical care of bedbug bites depends on the patient's clinical picture. Treatment of these bites is not usually required. However, if secondary infection occurs, apply local antiseptic lotion or antibiotic cream or ointment. Creams with corticosteroids and oral antihistamines may be advised in the presence of an allergic reaction. Infestation often leads to nervousness, anxiety, and insomnia.[3]
Papular Urticaria and Acute Urticaria for complete information on these topics.
To reduce bedbug infestations, use insecticides and eliminate bedbug hiding sites.[29] However, due to the development of insecticide resistance, new tools and techniques are needed for bed bug control. Behavior and physiology modifying chemicals may be exploitable for this purpose.[30]
Because bites occur on exposed skin surfaces, advise affected individuals to wear nightclothes that cover as much skin as possible.
A number of insecticides are effective, including permethrin, and diethyltoluamide is an excellent insect repellent. Bedbugs feeding after insecticide exposure may alter the effects of the pesticide on bedbug mortality.[31] Permethrin spray can be applied to clothing. Combined use of permethrin-treated clothing and cutaneous diethyltoluamide may be considered. In an African survey of rural homes, bed nets impregnated with permethrin were responsible for the disappearance of bedbugs.[32]
Note that encephalopathy may occur in children exposed to high concentrations of diethyltoluamide. Infant bedding can be treated separately with pyrethrums.
To prevent bedbugs from gaining access to the bed, try inserting bedposts of bedbug-free beds into containers of paraffin oil. However, bedbugs can be resourceful; they have been known to climb walls and across ceilings to drop onto their victims during the night. See the image below.
View Image | Treatment for bedbug bites is typically supportive. Local antiseptic lotions or antibiotic creams can be applied for secondary infections, whereas cor.... |
Structural insect proofing can be performed to prevent the bugs from entering homes and beds, in addition to using control measures such as spraying infested buildings with insecticides such as malathion. Eradication of a bedbug infestation may require a professional exterminator.
Bedbug control can be challenging. One approach is room heat treatment, vacuuming, and nonchemical pesticides, and possibly chemical ones.
A heat treatment method to eliminate bedbug infestations in room contents has been evaluated.[33] High temperatures caused temporary immobilization even with exposures that did not have lethal effects. One method for limited heat treatment of furniture and other room contents required equipment costing less than US$400 and provided an opportunity for residual pesticide application with minimal disruption in use of the treated room.
Baited traps may be effective tools for evaluating bedbug control programs and detecting early bedbug infestations. Carbon dioxide was significantly more attractive to bed bugs than heat.[34]
Widespread resistance to pyrethroid and neonicotinoid insecticides favors consideration of the newly developed fungal biopesticide Aprehend, containing Beauveria bassiana, against insecticide-resistant bedbugs.[35] Aprehend may be equally effective against insecticide-susceptible and insecticide-resistant bedbugs and represents a possible new tool for bedbug control. Insecticide resistance may develop to malathion, diazinon, and λ-cyhalothrin, rendering them ineffective against bed bugs in selected geographic areas.[36]
Bedbug management in homes and apartments may benefit from early detection, a key to slowing spread and reducing management cost.[37] A variety of passive monitors that detect low-level bedbug infestations are on the market.
At this time, no evidence suggests bedbugs actually transmit pathogens to humans.[38] Theoretically, failure to diagnose bedbug bites puts a patient at increased risk of hepatitis B or some other infection. Because bedbugs may at least theoretically transmit disease, the physician may be at medicolegal risk if the patient develops any such infection. Reinhardt et al suggest the delayed reaction time of skin to bites has implications in litigation, such as when people seek compensation from hotels.[21]
DEET is a highly effective bedbug repellent, but it has a substantial order and can dissolve certain plastics.[39]
Bedbugs can spread through ventilation ducts, water pipes, and gutters and can travel in clothing and luggage.[4] Travelers should examine hotel rooms, looking behind the headboard and in mattress seams, for evidence of bedbugs.
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
Clinical Context: Topical triamcinolone (0.1% cream) is an anti-inflammatory that is administered for intense, localized allergic reactions. This agent can be used to treat inflammatory dermatosis that is responsive to steroids.
Topical triamcinolone decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and reversing capillary permeability.
Clinical Context: Hydrocortisone is an adrenocorticosteroid derivative suitable for application to the skin or external mucous membranes. It decreases inflammation by suppression of the migration of polymorphonuclear leukocytes and reversal of increased capillary permeability.
Clinical Context: Clobetasol is a class I superpotent topical steroid; it suppresses mitosis and increases the synthesis of proteins that decrease inflammation and cause vasoconstriction. Clobetasol decreases inflammation by stabilization of lysosomal membranes, inhibition of polymorphonuclear leukocytes, and deregulation of mast cells.
Corticosteroids have anti-inflammatory properties and cause profound and varied metabolic effects. These agents modify the body's immune response to diverse stimuli.
Clinical Context: Chlorpheniramine is used to treat intense, localized allergic reactions. This agent competes with histamine or H1-receptor sites on effector cells in blood vessels and the respiratory tract.
Clinical Context: This is a first-generation antihistamine with anticholinergic effects that binds to H1 receptors in the CNS and the body. It competitively blocks histamine from binding to H1 receptors. It is used for symptomatic relief of symptoms caused by the release of histamine in allergic reactions.
Clinical Context: Loratadine selectively inhibits peripheral histamine H1 receptors. It is tolerated well, with rate of sedation not significantly different from placebo.
Clinical Context: Desloratadine is a long-acting tricyclic histamine antagonist selective for the H1-receptor. It is a major metabolite of loratadine, which, after ingestion, is extensively metabolized to the active metabolite 3-hydroxydesloratadine.
Clinical Context: Cetirizine selectively inhibits histamine H1 receptor sites in blood vessels, the GI tract, and the respiratory tract, which, in turn, inhibits the physiologic effects that histamine normally induces at H1 receptor sites. Once-daily dosing is convenient. Bedtime dosing may be useful if sedation is a problem.
Antihistamines are used to treat minor allergic reactions and anaphylaxis. These agents act by competitive inhibition of histamine at H1 receptor.
Bedbugs are parasitic arthropods from the family Cimicidae. They are typically less than 1 cm in length and reddish brown in color. Bedbugs can be found in furniture, floorboards, peeling paint, or other small spaces, most commonly in areas of clutter. These insects come out at night in search of prey upon which to feed, with peak feeding times just before dawn. Bedbugs are typically attracted to body heat, carbon dioxide, vibration, sweat, and odor. The image of a Cimex lectularius is shown courtesy of the US Centers for Disease Control and Prevention (CDC).
After bedbugs find a food source, they bite down with their mouths and inject anticoagulant and anesthetic compounds into the skin. Depending on the species, these parasites feed on the host blood via 1 of 2 mechanisms. Vessel feeders directly insert their mouthparts into superficial capillaries, whereas pool feeders damage the superficial tissue and feed on the accumulated blood. As bedbugs feed, their color may change as they swell with the host blood, as shown in this picture of a larval bedbug feeding on a volunteer host. Image courtesy of the US Centers for Disease Control and Prevention (CDC).
Bedbug bites themselves are typically painless. However, the subsequent allergic reaction that may develop can cause intense pruritus. While feeding, bedbugs may inject one of several pharmacologically active substances, including hyaluronidase, proteases, and kinins. These compounds may induce different skin reactions, such as erythema, wheals, vesicles, or hemorrhagic nodules. Repeated bites may sensitize individuals, leading to more pronounced cutaneous manifestations or systemic hypersensitivity reactions. The local trauma from bedbug bites can lead to secondary bacterial infection, causing ecthyma, cellulitis, or lymphangitis. There is some evidence that bedbugs may also be a vector for hepatitis B and Chagas disease. Histologic findings from bite-site biopsy specimens typically show eosinophilic infiltrates, which are indicative of the allergic nature of the reaction. The image shown is papular urticaria, which may develop from bedbug bites.
Bedbug bites themselves are typically painless. However, the subsequent allergic reaction that may develop can cause intense pruritus. While feeding, bedbugs may inject one of several pharmacologically active substances, including hyaluronidase, proteases, and kinins. These compounds may induce different skin reactions, such as erythema, wheals, vesicles, or hemorrhagic nodules. Repeated bites may sensitize individuals, leading to more pronounced cutaneous manifestations or systemic hypersensitivity reactions. The local trauma from bedbug bites can lead to secondary bacterial infection, causing ecthyma, cellulitis, or lymphangitis. There is some evidence that bedbugs may also be a vector for hepatitis B and Chagas disease. Histologic findings from bite-site biopsy specimens typically show eosinophilic infiltrates, which are indicative of the allergic nature of the reaction. The image shown is papular urticaria, which may develop from bedbug bites.
Treatment for bedbug bites is typically supportive. Local antiseptic lotions or antibiotic creams can be applied for secondary infections, whereas corticosteroid creams and oral antihistamines can be used for allergic reactions. Bedbugs can be eliminated through the use of permethrin insecticides, baited traps, special bedbug-free beds, and bed nets. Homemade methods, such as wrapping duct tape around bed legs as shown, may be effective, but bedbugs have been known to climb other objects and then fall down onto a bed. Image courtesy of Wikimedia Commons.
Human infestation with bedbugs, lice, and mites are common causes of dermatologic symptoms. Although these organisms thrive in conditions of overcrowding and decreased sanitation, Americans of all socioeconomic backgrounds may be at risk for infestation. Clinicians must maintain high suspicion in the appropriate set of clinical circumstances to identify and treat infestations, as they can cause substantial dermatologic and psychological discomfort for patients. Images courtesy of the US Centers for Disease Control and Prevention.
Bedbugs are parasitic arthropods from the family Cimicidae. They are typically less than 1 cm in length and reddish brown in color. Bedbugs can be found in furniture, floorboards, peeling paint, or other small spaces, most commonly in areas of clutter. These insects come out at night in search of prey upon which to feed, with peak feeding times just before dawn. Bedbugs are typically attracted to body heat, carbon dioxide, vibration, sweat, and odor. The image of a Cimex lectularius is shown courtesy of the US Centers for Disease Control and Prevention (CDC).
After bedbugs find a food source, they bite down with their mouths and inject anticoagulant and anesthetic compounds into the skin. Depending on the species, these parasites feed on the host blood via 1 of 2 mechanisms. Vessel feeders directly insert their mouthparts into superficial capillaries, whereas pool feeders damage the superficial tissue and feed on the accumulated blood. As bedbugs feed, their color may change as they swell with the host blood, as shown in this picture of a larval bedbug feeding on a volunteer host. Image courtesy of the US Centers for Disease Control and Prevention (CDC).
Bedbug bites themselves are typically painless. However, the subsequent allergic reaction that may develop can cause intense pruritus. While feeding, bedbugs may inject one of several pharmacologically active substances, including hyaluronidase, proteases, and kinins. These compounds may induce different skin reactions, such as erythema, wheals, vesicles, or hemorrhagic nodules. Repeated bites may sensitize individuals, leading to more pronounced cutaneous manifestations or systemic hypersensitivity reactions. The local trauma from bedbug bites can lead to secondary bacterial infection, causing ecthyma, cellulitis, or lymphangitis. There is some evidence that bedbugs may also be a vector for hepatitis B and Chagas disease. Histologic findings from bite-site biopsy specimens typically show eosinophilic infiltrates, which are indicative of the allergic nature of the reaction. The image shown is papular urticaria, which may develop from bedbug bites.
Treatment for bedbug bites is typically supportive. Local antiseptic lotions or antibiotic creams can be applied for secondary infections, whereas corticosteroid creams and oral antihistamines can be used for allergic reactions. Bedbugs can be eliminated through the use of permethrin insecticides, baited traps, special bedbug-free beds, and bed nets. Homemade methods, such as wrapping duct tape around bed legs as shown, may be effective, but bedbugs have been known to climb other objects and then fall down onto a bed. Image courtesy of Wikimedia Commons.