REVIEW

EDUCATIONAL OBJECTIVE: Readers will differentiate bedbug from other bites and advise patients on effective eradication of bedbug infestation. OMER IBRAHIM, MD USAMA MOHAMMAD SYED, MBBS, BSc KENNETH J. TOMECKI, MD Department of Dermatology, Faculty of Medicine, Imperial College London, UK Department of Dermatology, Cleveland Clinic Cleveland Clinic

Bedbugs: Helping your patient through an infestation

ABSTRACT edbugs have been unwelcome bedfellows B for humans for thousands of years. An in- Bedbugs—hematophagous parasitic of the crease in resistance, a ban on the genus —have been unwelcome bedfellows for dichloro-diphenyl-trichloroethane humans for thousands of years. With increases in popu- (DDT), increased international travel, and in- lation density, ease of travel, and insecticide resistance, creased population density in large cities have bedbugs have reemerged. As a result, physicians are led to an exponential rise in the incidence of often at the forefront in the diagnosis and treatment of bedbug infestations. Physicians are often at bedbug infestation. This review summarizes the biology the forefront of bedbug infestation diagnosis. and epidemiology of bedbugs and provides details on the diagnosis and treatment of bedbug infestation. See related editorial, page 212 KEY POINTS Once the diagnosis is suggested, symptom- atic treatment of the patient and extermina- The increase in pyrethroid resistance, the ban of DDT, the tion of the pests are essential, though time- ease and frequency of travel, and the increased popula- consuming, costly, and often problematic. tion density in large cities have led to an exponential rise Measures to eliminate infestation and to pre- in the incidence of bedbug infection. vent spread include identifi cation of the pest, early detection, patient education, and profes- Once the diagnosis is suggested, patients deserve sional eradication. symptomatic treatment, and extermination of the pests ■ becomes essential, though time-consuming, costly, and BEDBUGS: A BRIEF HISTORY often problematic. The term bedbug refers to the obligate para- sitic arthropod Cimex lectularius (the com- Measures to eliminate infestation and prevent spread mon bedbug) and, less commonly, its tropical include early detection, identifi cation of the pest, patient cousin C hemipterus. Bedbugs have coex- education, and professional eradication. isted with humans for centuries, dating back to the ancient Egyptians 3,500 years ago.1 Through the mid-20th century, about 30% of US households were infested with bedbugs.2 The introduction of pesticides during World War II markedly decreased the incidence, but with increased international travel, pesticide resistance, and the banning of certain pes- ticides in the last decade, bedbugs have re- doi:10.3949/ccjm.84a.15024 emerged worldwide.3

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TABLE 1 Common areas of bedbug infestation Mattress seams Box springs Headboards Bed linens, bedclothes Curtains Carpets Electrical outlets Wall and fl oor cracks Wallpaper Picture frames Luggage, suitcases FIGURE 1. The adult Cimex lectularius is a Couches, other furniture red-brown, wingless, oval-shaped insect measuring about 4 to 5 mm in length.

Source: US Centers for Disease Control and Prevention, http://phil.cdc.gov/. and 5:00 am. Though wingless, they success- fully navigate towards their human host, at- tracted by emitted heat and carbon dioxide.2 ■ BIOLOGY Once attached to human skin, the bedbug Bedbugs are red-brown, wingless, oval-shaped bite releases enzymes and chemicals includ- insects measuring 4 to 5 mm in length (Fig- ing nitrophorin and nitric oxide that facili- The female ure 1). They are hematophagous ectoparasites tate bleeding; these substances are respon- bedbug that preferentially feed on human blood, al- sible for the resultant dermatitis. (Of note, though they feed on some animals as well.2 bedbugs with experimentally excised salivary lays 5 to 8 eggs Cimex lectularius dwells in temperate cli- glands do not cause skin disease in humans.6) per week, mates and C hemipterus in more tropical cli- After feeding for 3 to 20 minutes, the length mates, but overlap and interbreeding are com- 500 eggs in and weight of the arthropod can increase mon. The usual life cycle is about 6 months, by 50% to 200%. A fully sated bedbug can her lifetime, but some bugs live 12 months or longer. The survive for a year until its next meal.2,7 Even and each female bedbug lays 5 to 8 eggs per week, or ap- if an establishment, home, room, or article proximately 500 eggs in her lifetime, and each of clothing infested with bedbugs has been egg hatches 4 egg hatches in 5 to 10 days. abandoned for several months, without in 5 to 10 days These photophobic parasites do not live on proper eradication the item still represents their human hosts but rather simply visit for a a possible nidus for recurrent disease if used, meal. They cohabitate in dark locations, at- inhabited, or worn again. tacking human hosts when they are inactive or sleeping for long periods of time. Common liv- ■ EPIDEMIOLOGY ing areas include mattress seams, box springs, bed linens and clothes, wallpaper seams, elec- From the earliest documented cases of Cimex trical outlets, and furniture seams (Table 1).5 in ancient Egyptian tombs to the mid-1900s, The female bedbug lays her eggs in these se- the cohabitation of humans and bedbugs was cluded crevices, ensuring their safety until seen as inevitable. With the introduction of hatching. The dense nests of adult bedbugs, DDT 60 years ago, the bedbug population their eggs, and accumulated fecal matter allow signifi cantly decreased.8 Since DDT’s pro- for easy visual identifi cation of infestation.5 hibition, coupled with increased travel and Bedbugs typically feed between 1:00 am heightened resistance to over-the-counter

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FIGURE 2. Bedbug bites begin as pink mac- FIGURE 3. The clustering of bedbug bites ules that progress to papules (as seen here), in groups of three in a linear pattern—the large plaques, or hives. Some papules and “breakfast, lunch, and dinner” sign—can plaques may have a central crust or erosion help distinguish a bite from a diffuse urti- suggesting a bite. carial response. , the bedbug population has re- sault. Some papules and plaques may have a emerged exponentially.9,10 central crust or erosion suggesting a bite. Infestations have been reported world- Bites are typically intensely pruritic, and wide, on every continent, and in all 50 of the occasionally, hypersensitive victims can de- United States. In Australia, infestations have velop bullae, necrotic plaques, or even vascu- risen 4,500% in the last 10 to 15 years.11 In the litis. New papules and plaques form as older United States, infestation occurs exclusively ones heal. Some patients may have fever and with C lectularius and the incidence is rising. malaise.13 About 30% of patients may not Philadelphia and New York City are among have skin disease from bedbugs, making diag- the most bedbug-infested US cities. New York nosis in those individuals impossible. City experienced a 2,000% increase in bedbug The nonspecifi c nature of this presenta- 8 complaints between 2004 and 2009. tion and the subsequent diffi culty in prompt The waist, Bedbugs can be transmitted either through diagnosis can lead to a prolonged period of active migration of colonies from one area morbidity for the patient, as well as increasing axillae, and to another adjacent living area through wall the window of opportunity for the bedbugs to uncovered parts spaces or ventilation, or through passive affect other surrounding individuals. transportation in luggage, clothing, furniture, of the body are used mattresses, bookbags, and other personal ■ THE DIFFERENTIAL DIAGNOSIS IS BROAD the usual sites 1 items. Although infestation affects people of Commonly, bedbug bites have been misdiag- for bedbug bites all socioeconomic classes and backgrounds, nosed as drug eruptions, food allergies, derma- the likelihood increases in people who fre- titis herpetiformis, staphylococcal or varicella quently travel and people who live in lower infection, and scabies, as well as other arthro- income neighborhoods with tightly packed pod bites.11 This broad differential diagnosis apartments. Bedbug infestations are also com- can often be narrowed by careful observation mon in refugee camps: 98% of the rooms in of the bite distribution. The clustering of bites a refugee camp in Sierra Leone had bedbugs, in groups of 3, often in a linear pattern, some- and almost 90% of the residents had signs of 12 times overlying blood vessels, is known as the bites. Unlike scabies, direct person-to-per- “breakfast, lunch, and dinner” sign (Figure 3), son, skin-to-skin transfer is rare. and this can help to guide the clinician toward ■ the diagnosis of a bite as opposed to a diffuse CLINICAL FINDINGS urticarial response.2 Bedbug bites are analogous, almost identical, If the characteristic clusters of bites are not to other arthropod bites: bites begin as pink present, distinguishing clinically between the macules that progress to papules (Figure 2), various causes of pruritic urticarial lesions is large plaques, or wheals (hives).13 Bites can diffi cult. Subtle clues that point towards bed- arise minutes or even days after the initial as- bug bites can be that the rash appears to be

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most edematous in the morning and fl attens as vectors of disease. Some 45 known patho- throughout the day, as the bites occur typi- gens have been isolated from the Cimex spe- cally during sleep.14 Likewise, the rash associ- cies including hepatitis B, human immunode- ated with bedbug bites has also been reported fi ciency virus (HIV), Trypanosoma cruzi, and to last longer, to blanch less, and to be less methicillin-resistant Staphylococcus aureus. To responsive to steroid and antihistamine treat- date, however, there is no evidence to demon- ment than other urticarial rashes.14 If a skin strate transmission of pathogens to humans.5 biopsy specimen is available, histologic assess- ment can help to rule out similarly presenting ■ TREATMENT AND ERADICATION conditions such as prodromal bullous pemphi- Treatment is mainly symptomatic—systemic goid, dermatitis herpetiformis, and urticarial antihistamines and topical corticosteroids to dermatosis, even if it cannot provide a defi ni- 2 15 reduce pruritus and alleviate the dermatitis. tive answer as to the etiology. Patients should be instructed to avoid scratch- Bedbug bites vs other arthropod bites ing to prevent infection. Secondary bacterial Once a bite is suspected, differentiating be- infection can be treated with topical or sys- tween bedbug and other arthropod bites is the temic antibiotics. Rare cases of bite-induced next challenge. asthma or anaphylaxis necessitate appropriate Once again, a detailed assessment of the emergency treatment. Extermination of infes- location of the bites can yield valuable in- tation is critical to therapy. formation. The waist, axillae, and uncovered If bedbug infestation is suggested, mat- parts of the body are the usual sites for bedbug tresses, bedding, sleeping areas, and bed cloth- bites.2 Likewise, infl ammatory papules along ing should be inspected for insects, eggs, and the eyelid (the “eyelid sign”) are highly sug- fecal spotting. Adhesives or traps that emit gestive of a bedbug bite.16 heat or carbon dioxide can be used to capture The scant involvement of covered body the bedbugs. During widespread infestation, areas, the lack of shallow burrows in the skin, the arthropods release a pungent odor, which and the lack of scabetic elements on skin allows trained dogs to detect them with 95% Ensuring 19 scrapings exclude scabies as a diagnosis. to 98% accuracy. resolution of Skin biopsy is not helpful in differentiating Eradication techniques an infestation arthropod bites, as the histologic fi ndings are Once infestation is confi rmed, patients should requires repeat nonspecifi c. The key to a defi nitive diagnosis contact an exterminator who can confi rm the in these cases is identifi cation of the suspected presence of bedbugs. Typical eradication mea- inspections and bug in characteristic locations. Patients should sures often require nonchemical control and retreatment be encouraged to carefully inspect mattresses, chemical pesticides. fl oorboards, and other crevices for the small Professional exterminators have special ovaloid bugs or the reddish-brown specks of equipment that can heat a room to 48 to 50°C heme and feces they typically leave behind on 15 (118–122°F). Heat sustained at this temper- bed linens. A positive reported sighting of ature for 90 minutes is suffi cient to kill bed- the bugs can lend credence to the diagnosis, bugs.20 whereas capture and laboratory assessment of The infested area should be vacuumed daily, a specimen is ideal. and vacuum bags and unwanted items should ■ be sealed in plastic before discarding. Clothing, BEDBUGS AS DISEASE VECTORS linens, and infested fabrics should be washed Extracutaneous manifestations of bedbug as- and dried in heat at 60°C (140°F) or greater. sault are rare. Anaphylaxis to proteins in Mattresses and furniture should be sealed Cimex saliva may occur, as well as signifi - in a special plastic that allows treatment with cant blood loss, even anemia, from extensive heat, steaming, or pesticides. Most profes- feeding.17 Bedbug infestations can exacerbate sional pesticides contain , but re- asthma, preexisting mental illness, anxiety, sistance to these products is common, neces- and insomnia.18 Since bedbugs extract blood sitating the use of multiple formulations to from hosts, they have a putative ability to act overcome resistance.8

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Over-the-counter pesticides, almost exclu- ices, placing luggage on a luggage rack away sively pyrethroids, are variably effective and from the fl oor and bed, and careful examina- potentially hazardous to consumers.8 Patients tion of acquired second-hand items.7 must be advised to follow label directions to avoid adverse effects and toxicity. Educating patients is the key to success Alternative chemical eradication meth- While all of the above eradication techniques ods to circumvent the problem of resistance are important curative strategies, the success include piperonyl butoxide, S-methoprene, of any treatment is contingent on appropriate , (diatomaceous earth ), patient education about the nature of the prob- and sulfuryl fl uoride. Recent research has also lem. posited the use of antiparasitic agents such as Resolving a bedbug infestation is notorious- ivermectin and moxidectin in cases of resistant ly diffi cult and requires meticulous adherence bedbug infestation, with promising results.21 to hygiene and cleansing instructions through- All extermination products and techniques out the household or institution for a sustained have variable risks, effi cacies, and costs,8 and period of time. Information from sources such repeat inspections and retreatment are often as the US Environmental Protection Agency required. (www.epa.gov) can empower patients to per- Prevention strategies include visual in- form the necessary eradication protocols, and spection of possibly infested rooms, with par- clinicians should routinely recommended them ticular attention to mattress seams and crev- as part of a holistic treatment strategy. ■

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