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.
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.
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.
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The bedbug is a flat, oval, reddish brown insect that turns violaceous after feeding. Courtesy of Colonel Dirk M. Elston, MD (from Elston, 2000).
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Bedbugs feeding on a human host. Courtesy of Colonel Dirk M. Elston, MD (from Elston, 2000).
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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.
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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).
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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).
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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.
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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.
