Bedbugs

INTRODUCTION — Bedbugs are obligate, blood-feeding insects that infest human dwellings and inflict bites that can cause local skin reactions in humans (picture 1A-E). Management involves confirmation and eradication of the infestation. Antipruritic agents and psychologic support for victims also may be needed.

The clinical features, diagnosis, and management of bedbug infestations will be reviewed here.

TAXONOMY — Bedbugs (also written as "bed bugs") are true bugs of the order Hemiptera and family Cimicidae. Cimicids commonly infest human, bird, and bat habitats. As parasites, cimicids are unique because they are obligate blood feeders but do not remain on the host to complete their life cycle. Rather, they hide in the surrounding habitat. Cimex lectularius and Cimex hemipterus are the two bedbug species that most commonly affect humans. (See 'Life cycle' below.)

MORPHOLOGY — Correct identification of bedbugs is important for implementing proper control measures. Bat bugs (Cimex adjunctus and other species) and swallow bugs (Oeciacus vicarius) are other members of the Cimicidae family that may be mistaken for bedbugs and may incidentally bite humans (picture 2).

Bedbugs have flat, red-brown, oval bodies and are similar in size to a dog tick (picture 1A). The eyes are widely separated, and the mouthparts are retroverted with the labium slender and elongated, forming a three-segmented rostellum (rostrum). The wings are reduced to hemelytral pads, with membranous hindwings vestigial or absent. The pronotum (a plate-like structure covering the dorsal thorax) has a concave anterior margin where it connects to the head. Bristles project laterally along the margins of the pronotum, starting behind the eye and continuing along the lateral edge (picture 2). Bristles can also be present on the dorsal surface. The antennae have four segments, with the distal three segments long and slender. The abdomen has eleven segments that expand during feeding, exposing intersegmental membranes.

Adult C. lectularius range in size from 5 to 7 mm, while nymphs (juveniles) may be as small as 1.5 mm. C. hemipterus is somewhat longer than C. lectularius.

Prior to a blood meal, adult bedbugs are brown in color. After feeding, the color becomes more dull red, and the body of the bedbug elongates and is no longer flat [1]. Smaller nymphs are translucent prior to feeding and become bright red after feeding.

LIFE CYCLE — The bedbug life cycle consists of egg, nymph, and adult stages. The eggs hatch in 4 to 10 days. Nymphs undergo five nymphal stages, each requiring a blood meal before molting to the next stage [2]. The fifth stage molts into an adult. The average life span of an adult bedbug is 6 to 12 months [3].

Bedbugs spend the majority of their lives hiding in harborages, especially during the daytime. Bedbugs seldom inhabit the resting surface of beds or chairs. Instead, they hide peripherally in cracks and crevices of mattresses, cushions, bed frames, and other structures. In resource-limited countries, bedbugs may inhabit the cracks and crevices of mud and daub houses, as well as the thatched roof. The female deposits her eggs in these cracks and crevices.

Bedbugs respond to aggregation pheromones, resulting in clustering behavior, although solitary bedbugs may also be found as they disperse from these aggregation sites. Increased protection from desiccation and associated growth benefits in the nymphal stages are potential advantages of grouping [4].

Dispersal of bedbugs may be enhanced by the overcrowding of aggregation sites and the release of alarm pheromones by bedbugs in aggregates that are disturbed. Multiple small aggregation sites, scattered around the living spaces, is a major reason why bedbugs are hard to detect and eradicate.

Local skin reactions related to bedbugs occur from the direct feeding of bedbugs. Bedbugs are attracted by warmth and carbon dioxide and often feed while the victim sleeps. Feeding also may occur when the victim is quiescent, resting, or with their attention diverted elsewhere. Bedbugs inject an anticoagulant to aid with feeding and usually feed without detection by the host. A complete blood meal lasts approximately 5 to 10 minutes [5]. Adult bedbugs can survive for up to one year without feeding [3].

Bedbugs may not die in the colder winter months; some survival occurs at temperatures above -12°C, even after one week of continuous exposure [6].

EPIDEMIOLOGY — Bedbugs are present throughout the world. C. lectularius is found in temperate climates, and C. hemipterus is most prevalent in tropical climates, although the ranges of these species overlap [7]. Occasionally, tropical bedbugs may appear in more temperate areas because of international travel. In addition, C. lectularius can appear in urbanized, tropical areas.

Bedbug infestations are more common in economically disadvantaged areas but also occur in sites frequented by travelers or in the homes of individuals who travel frequently [8]. Infestations are also common in refugee camps [9]. Other factors may influence risk for bedbug infestation. A study of approximately 2800 call inquiries for bedbug eradication from a pest control company in Budapest found positive associations between call inquiry rates and urban location, lower educational status of inhabitants, smaller apartments, and timing between March and December [10].

Within multifamily and institutional buildings, bedbugs will move among rooms or may spread when items harboring bedbugs are moved within the building. Bedbugs are increasingly being identified in office environments, but spread within that environment is often limited [11].

CLINICAL MANIFESTATIONS — Bedbugs inflict painless bites on exposed areas of skin at night and are rarely seen by the victim. Bites typically occur on the face, neck, hands, and arms.

Skin reactions — Reactions to bedbug bites vary. In some people, reactions do not occur, and the only evidence of a bite is a small punctum [3]. Older adults may be less likely to develop skin reactions than younger individuals [12].

The classic appearance of a bedbug bite reaction is a 2 to 5 mm erythematous papule or wheal with a central hemorrhagic punctum (picture 1B-E) [3,5]. Pruritus is common.

Some patients have only asymptomatic, purpuric macules at the sites of bites. Occasionally, bullous reactions occur [1,13,14]. Bedbug bites may also appear as papular urticaria or may mimic urticaria [15,16]. Individuals with papular urticaria may have immunoglobulin G (IgG) antibodies against C. lectularius, Culex pipiens, and Pulex irritans [16]. (See "Insect and other arthropod bites", section on 'Papular urticaria'.)

Reactions may be noticed upon awakening or one to several days after the bites. Occasionally, the onset of a skin reaction is delayed for up to 10 days [17].

A linear series of bites found upon awakening suggests bedbugs but is not always present. The linear pattern may occur as a single bedbug probes multiple times looking for a productive capillary or may result from multiple bedbugs feeding along a zone of exposed skin.

Course — Untreated bites usually resolve in one week [3]. New erythematous papules or wheals can accumulate as older ones heal.

COMPLICATIONS — Occasionally, bedbug bites can become secondarily infected, producing impetigo or cellulitis. Excoriated or impetiginized areas may take several weeks to resolve.

Extreme infestations associated with multiple repeated feedings by bedbugs may result in anemia [18]. Rarely, bedbug feeding results in anaphylaxis [19].

Although pathogens such as hepatitis B virus [20-23], Trypanosoma cruzi [24,25], methicillin-resistant Staphylococcus aureus (MRSA) [26,27], Francisella tularensis [28], and Wolbachia [29] have been detected in bedbugs, transmission of these diseases has neither been clinically demonstrated nor observed. There is little evidence to suggest bedbugs are competent vectors for human disease [3,30].

HISTOPATHOLOGY — The histopathologic findings of bedbug bites are nonspecific. Urticaria-like skin reactions often demonstrate edema in the upper dermis and a perivascular, inflammatory infiltrate with lymphocytes, eosinophils, and mast cells. A small number of interstitial eosinophils may also be present [31].

Bullous bedbug bites may exhibit intraepidermal edema, subepidermal edema, and a mixed dermal inflammatory infiltrate [32]. In addition, histopathologic features consistent with cutaneous vasculitis have been reported in a patient with bullous lesions [14].

DIAGNOSIS — Although clinical findings can suggest bedbug bites, the diagnosis requires detection of bedbugs in the patient's environment. Skin biopsies yield nonspecific results and are usually unnecessary.

When to suspect bedbug infestation — In general, bedbug bites should be suspected in patients with recurrent, pruritic, erythematous papules or wheals that persist for several days. Because the physical manifestations of bedbug bites are nonspecific, a careful history and full skin examination should be performed to detect additional findings suggestive of bedbugs or other conditions.

Features that support a diagnosis of bedbugs include:

●Potential exposure to bedbugs (recent travel, residence within building with known bedbug infestation)

●Pruritic skin reaction characterized by erythematous papules or wheals

●Detection of new skin reactions upon waking in morning

●Skin reactions in a linear configuration

●Cohabitants with similar symptoms

The absence of any of these features does not exclude the diagnosis. If features suggestive of other arthropod bites or skin disorders are not detected, inspection of the patient's residence for bedbugs is prudent. (See 'Differential diagnosis' below.)

Confirming the diagnosis — The presence of bedbugs is necessary to confirm the diagnosis. A pest control service is the preferred method for detecting bedbugs. Detection involves careful visual inspection of typical harborages, placement of passive (physical or adhesive) or active (heat- or carbon dioxide-emitting) traps, or deployment of trained bedbug-detection dogs [33,34].

Bedbugs are most likely to be found near feeding sites (eg, sleeping areas) but may be found in other locations.

Small infestations of bedbugs are difficult to detect and may be suspected if specks of feces or blood are found on linens, mattresses, or behind wallpaper [35]. Caste skins from moulting bedbugs also may be found.

Bedbug infestation can produce a recognizable pungent odor that supports the diagnosis [5]. However, the odor typically occurs only with chronic and widespread infestations.

Skin biopsy results are nonspecific and do not confirm a diagnosis of bedbug bites. In challenging cases, a skin biopsy can be performed to rule out other skin diseases. (See 'Differential diagnosis' below.)

DIFFERENTIAL DIAGNOSIS — Bedbug bites may resemble a wide variety of disorders. Examples of disorders in the differential diagnosis include:

●Other arthropod bites – Other biting arthropods, especially bat bugs, swallow bugs, fleas, and parasitic mites, can produce bites similar to bedbugs (picture 3). Humans are not the preferred food source for bat bugs and swallow bugs, but incidental bites may occur in the setting of infestations in human dwellings. Bat bugs and swallow bugs closely resemble bedbugs; examination of the insect by an entomologist can aid in correct identification (picture 2).  

Scabies is a common disorder caused by infestation of Sarcoptes scabiei. Patients often have intensely pruritic papules with predilection for particular sites, such as sides and webs of the fingers, wrists, axillae, areolae, and genitalia (picture 4A-B). The detection of the scabies mite, feces, or eggs with microscopic examination confirms the diagnosis. (See "Scabies: Epidemiology, clinical features, and diagnosis".)

Cheyletiella mites and other mite species often associated with cats, dogs, rabbits, rats, or birds are a common cause of grouped bites. (See "Insect and other arthropod bites".)

●Primary skin disorders – Skin diseases in the differential diagnosis may include pruritic, papular eruptions, such as prurigo nodularis and urticaria (picture 5 and picture 6). The papules of prurigo nodularis are firm and more persistent than bedbug bites. The duration of individual lesions of urticaria is shorter than bedbug bites, with lesions lasting for less than 24 hours. Urticaria lesions usually lack a central punctum. Less common disorders, such as dermatitis herpetiformis (picture 7), pityriasis lichenoides et varioliformis acuta (picture 8), and lymphomatoid papulosis (picture 9), may also enter the differential diagnosis. Skin biopsies are useful for the diagnosis of these disorders. (See "Prurigo nodularis" and "New-onset urticaria" and "Dermatitis herpetiformis" and "Pityriasis lichenoides et varioliformis acuta (PLEVA)" and "Lymphomatoid papulosis".)

●Displaced concern for infestation – Individuals may strongly believe they have bedbug infestation in the absence of true infestation. These thoughts may be triggered by exposure to someone with bedbugs, skin symptoms secondary to other disorders, information from social contacts or media, or other factors.

Such beliefs may cause individuals to take unnecessary steps to eradicate bedbugs. These individuals can often be convinced to take appropriate steps to confirm whether bedbug infestation or another condition is responsible.

●Delusional infestation (also called delusional parasitosis or Ekbom syndrome) – Delusional infestation is a psychiatric disorder in which patients have a fixed, false belief that they are infected by insects or other living organisms [36]. The physical examination may reveal excoriations or other self-induced skin injury; the erythematous papules or wheals often associated with bedbug bites are absent. Knowledge of or prior experience with infestation is a potential contributing factor. (See "Delusional infestation: Epidemiology, clinical presentation, assessment, and diagnosis".)

MANAGEMENT

Treatment of bites — Bedbug bites spontaneously resolve, and treatment of the bites is not mandatory. However, significant pruritus is common and may be improved with a low- or medium-potency topical corticosteroid (eg, triamcinolone acetonide 0.1%), an oral antihistamine, or both (table 1) [5]. Of note, antihistamines can suppress the symptoms and signs of bites and may reduce the patient's ability to detect an ongoing infestation. (See 'Clinical manifestations' above.)

Patients should maintain good hygiene and avoid scratching to prevent infection. Secondary infection should be treated with appropriate antibiotics. (See "Impetigo" and "Acute cellulitis and erysipelas in adults: Treatment".)

Psychologic support — Victims of bedbug infestations may experience varying degrees of stress, anxiety, and depression. Clinicians should inquire about such symptoms and provide counseling, referral, or treatment, if indicated.

Examples of psychosocial effects of infestation include [37,38]:

●Patients may worry about bedbugs biting them or their family members, which can disrupt sleep.

●Patients may be shunned by friends or others in the community.

●Patients may isolate themselves, avoiding family and friends, fearing spread of the infestation.

●Patient or employer concerns can lead to suspension of work.

●Management of infestations can be disruptive and expensive.

●Patients experiencing significant psychologic distress over an infestation may engage in dangerous, inappropriate practices in an attempt to eradicate the infestation (eg, misuse of insecticides) [39].

Eradication — Once infestation is confirmed through the detection and correct identification of bedbugs, measures to eradicate infestation can be implemented.

Eradication of bedbugs is difficult because of their continual production of new, discrete aggregation sites (see 'Life cycle' above). Control of infestations requires an experienced pest management professional. Victims should refrain from attempting control measures themselves [40].

Preferred methods of eradication include application of insecticides and heat treatment. Combinations of insecticides are generally used to avoid failure due to resistance [41,42]. Use of long-lasting residual insecticides are necessary for heavy infestations [43]. All insecticides must be applied carefully and according to label directions.

Heat treatment involves use of equipment to heat rooms to a lethal temperature. All stages of bedbugs can be killed at 50°C (122°F). Failure of heat treatments may result from failure to reach a lethal room temperature in all infested areas or reinfestation [44]. The capability of bedbugs to develop heat resistance appears to be limited [45].

When insecticides and heat treatment are not feasible, physical removal of bedbugs may reduce the severity of infestation, although it is unlikely to completely eradicate the infestation. A thin plastic card or a thin-bladed paint scraper can be used to dig bedbugs out of cracks and crevices. Placement of interceptor (pitfall) traps at the base of beds and furniture may aid in control of bedbug infestations [46]. Pyrethroid-treated bednets and mattress encasements may reduce the number of bites, but resistance to pyrethroids is present in some bedbug populations and is spreading [47,48].

Supplemental methods to reduce the number of bedbugs can aid in eradicating infestations and include vacuuming and laundering or freezing bedding and other infested fabrics. Items that are laundered should be washed and dried in a dryer on a hot setting to kill bedbugs. The duration of freezing required is dependent on freezer temperature, with higher temperatures requiring longer freeze durations [6,49]. For home freezers with a typical target temperature of -18°C (0°F), freezing infested items for at least three to four days can be sufficient [6].

Although ingestion of boric acid by bedbugs has successfully killed bedbugs in an experimental setting, application of boric acid powder in infested areas does not appear to be an effective method for killing bedbugs and eradicating infestations [50].

PREVENTION — Certain measures may be helpful for preventing bedbug infestation [3]:

●Visual examination of hotel rooms or other new sleeping areas for bedbugs or bedbug feces prior to use, with particular attention to mattress cords and crevices in box springs.

●Placement of luggage on a luggage rack or away from the bed while traveling. Placement of worn garments in a sealed plastic bag to minimize bedbug attraction to worn clothing [51].

●Careful examination of "used" items, such as items from garage sales or resale shops (especially bedding items), for bedbugs or bedbug feces prior to bringing them inside the home.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Bedbugs".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Bedbugs (The Basics)")

●Beyond the Basics topics (see "Patient education: Bedbugs (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Overview – Bedbugs are obligate, blood-feeding insects that inhabit human dwellings and may cause skin reactions in humans (picture 1A and picture 2). Bedbugs closely resemble bat bugs and swallow bugs, related organisms that typically feed on animal hosts but may incidentally bite humans. (See 'Taxonomy' above and 'Morphology' above.)

●Epidemiology – Bedbugs are present worldwide. Spread of infestation can occur through transportation of items harboring bedbugs, as may occur with travel or acquisition of used furniture, or through direct movement of bedbugs in multifamily buildings or institutions. (See 'Epidemiology' above.)

●Life cycle – Bedbugs do not live on humans. Rather, they tend to inhabit cracks and crevices of mattresses, cushions, bed frames, or other structures. Bedbugs are attracted to the host by warmth and carbon dioxide and generally feed at night while the victim sleeps. (See 'Life cycle' above.)

●Clinical manifestations – Skin reactions to bedbugs vary, ranging from no reaction to pruritic papules or wheals, purpuric macules, or bullae (picture 1B-E). Reactions are typically noticed upon awakening or within a few days after the bites. A linear series of bites is a potential but not consistent finding. (See 'Clinical manifestations' above.)

●Diagnosis – Confirmation of the diagnosis of bedbug bites requires detection of bedbugs in the victim's environment. Inspection of the victim's residence by a professional pest control service is the preferred method for detection. (See 'Diagnosis' above.)

●Infestation management – Management of bedbug infestation consists of eradication of the infestation through employment of a professional pest control service. The primary methods include application of insecticides and heat treatment. When such interventions are not feasible, physical removal of detected bedbugs may reduce the severity of infestation but is unlikely to eradicate the infestation. (See 'Eradication' above.)

●Patient management – Bedbug bites resolve spontaneously. Topical corticosteroids and oral antihistamines may reduce associated pruritus. Psychologic support services can be beneficial for some victims. (See 'Treatment of bites' above and 'Psychologic support' above.)