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Bedbugs: Helping your patient through an infestation

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CLINICAL FINDINGS

Bedbug bites
Figure 2. Bedbug bites begin as pink macules that progress to papules (as seen here), large plaques, or hives. Some papules and plaques may have a central crust or erosion suggesting a bite.

Bedbug bites are analogous, almost identical, to other arthropod bites: bites begin as pink macules that progress to papules (Figure 2), large plaques, or wheals (hives).13 Bites can arise minutes or even days after the initial assault. Some papules and plaques may have a central crust or erosion suggesting a bite.

Bites are typically intensely pruritic, and occasionally, hypersensitive victims can develop bullae, necrotic plaques, or even vasculitis. New papules and plaques form as older ones heal. Some patients may have fever and malaise.13 About 30% of patients may not have skin disease from bedbugs, making diagnosis in those individuals impossible.

The nonspecific nature of this presentation and the subsequent difficulty in prompt diagnosis can lead to a prolonged period of morbidity for the patient, as well as increasing the window of opportunity for the bedbugs to affect other surrounding individuals.

THE DIFFERENTIAL DIAGNOSIS IS BROAD

Clustering of bedbug bites in groups of three.
Figure 3. The clustering of bedbug bites in groups of three in a linear pattern—the “breakfast, lunch, and dinner” sign—can help distinguish a bite from a diffuse urticarial response.

Commonly, bedbug bites have been misdiagnosed as drug eruptions, food allergies, dermatitis herpetiformis, staphylococcal or varicella infection, and scabies, as well as other arthropod bites.11 This broad differential diagnosis can often be narrowed by careful observation of the bite distribution. The clustering of bites in groups of 3, often in a linear pattern, sometimes overlying blood vessels, is known as the “breakfast, lunch, and dinner” sign (Figure 3), and this can help to guide the clinician toward the diagnosis of a bite as opposed to a diffuse urticarial response.2

If the characteristic clusters of bites are not present, distinguishing clinically between the various causes of pruritic urticarial lesions is difficult. Subtle clues that point towards bedbug bites can be that the rash appears to be most edematous in the morning and flattens throughout the day, as the bites occur typically during sleep.14 Likewise, the rash associated with bedbug bites has also been reported to last longer, to blanch less, and to be less responsive to steroid and antihistamine treatment than other urticarial rashes.14 If a skin biopsy specimen is available, histologic assessment can help to rule out similarly presenting conditions such as prodromal bullous pemphigoid, dermatitis herpetiformis, and urticarial dermatosis, even if it cannot provide a definitive answer as to the etiology.15

Bedbug bites vs other arthropod bites

Once a bite is suspected, differentiating between bedbug and other arthropod bites is the next challenge.

Once again, a detailed assessment of the location of the bites can yield valuable information. The waist, axillae, and uncovered parts of the body are the usual sites for bedbug bites.2 Likewise, inflammatory papules along the eyelid (the “eyelid sign”) are highly suggestive of a bedbug bite.16

The scant involvement of covered body areas, the lack of shallow burrows in the skin, and the lack of scabetic elements on skin scrapings exclude scabies as a diagnosis.

Skin biopsy is not helpful in differentiating arthropod bites, as the histologic findings are nonspecific. The key to a definitive diagnosis in these cases is identification of the suspected bug in characteristic locations. Patients should be encouraged to carefully inspect mattresses, floorboards, and other crevices for the small ovaloid bugs or the reddish-brown specks of heme and feces they typically leave behind on bed linens.15 A positive reported sighting of the bugs can lend credence to the diagnosis, whereas capture and laboratory assessment of a specimen is ideal.

BEDBUGS AS DISEASE VECTORS

Extracutaneous manifestations of bedbug assault are rare. Anaphylaxis to proteins in Cimex saliva may occur, as well as significant blood loss, even anemia, from extensive feeding.17 Bedbug infestations can exacerbate asthma, preexisting mental illness, anxiety, and insomnia.18 Since bedbugs extract blood from hosts, they have a putative ability to act as vectors of disease. Some 45 known pathogens have been isolated from the Cimex species including hepatitis B, human immunodeficiency virus (HIV), Trypanosoma cruzi, and methicillin-resistant Staphylococcus aureus. To date, however, there is no evidence to demonstrate transmission of pathogens to humans.5

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Bedbugs: Awareness is key

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