Approach

Diagnosis is based primarily on typical clinical presentation and a suggestive history. Further investigation is not usually necessary.

History and physical examination

Social and travel history are essential in determining risk of exposure to infestation. Recognised risk factors include sleeping in a high-turnover environment (e.g., hotel, hall of residence, or homeless shelter), recent travel, and the presence of second-hand furniture and/or mattresses in the home.[4][9][10]​​[20]​​​ Any sighting of bed bugs in the patient's environment (e.g., crevices of mattresses, bed bases, and bed headboards and behind skirting boards) should be noted. Occasionally, patients may report specks of blood or faeces on their bed sheets or mattress. Patients may also report a sweet, musty odour, which is emitted by bed bugs and is characteristic of infestation.[2]​ Ink dot-like spots on headboards and mattresses or blood stains on sheets are also clues to bed bug infestations in the bedroom.[25] However, when asked, they will often deny knowledge of any recent insect bite. Patients often report new lesions in the morning and may describe an intense pruritus. Although lesions are not usually painful, patients may report pain or a burning sensation.

Patients most commonly present with erythematous papules, 1 to 5 mm in size, arranged in a curved or linear pattern on skin exposed during sleep (e.g., face, neck, arms, legs, and shoulders).[7]​ A small central haemorrhagic punctum may be seen.[3][12]​ Lesions may occur hours to days after being bitten.[7]​ The interval between bite and reaction may decrease as the host is repeatedly exposed.[8] Other less commonly reported clinical presentations include papular or diffuse urticaria, bullous lesions, and, rarely, anaphylaxis.[3][7]​​[Figure caption and citation for the preceding image starts]: Cimex lectularius, collected in a hotel in urban GeorgiaCourtesy of the CDC [Citation ends].com.bmj.content.model.Caption@20ea2bc9[Figure caption and citation for the preceding image starts]: Cimex lectulariusCourtesy of the CDC [Citation ends].com.bmj.content.model.Caption@f8a4d3[Figure caption and citation for the preceding image starts]: Bed bug bites showing numerous erythematous papulesFrom the contributors' personal teaching collection (Julian J. Trevino, David R. Carr, Suzanne L. Dundon); used with permission [Citation ends].com.bmj.content.model.Caption@53f3b906[Figure caption and citation for the preceding image starts]: Linear distribution of papulesFrom the contributors' personal teaching collection (Julian J. Trevino, David R. Carr, Suzanne L. Dundon); used with permission [Citation ends].com.bmj.content.model.Caption@6aa0c7a5

Laboratory investigations

Diagnosis is based on clinical grounds, and further investigation is rarely necessary. A skin scraping of lesion (with mineral oil preparation) may be useful to exclude scabies as an alternative diagnosis. No bed bug-specific allergen-based tests are available for prick or intradermal skin testing to confirm bed bugs as an aetiological cause of urticaria.[3] Rarely, a skin biopsy may be performed, although histopathological findings are usually non-specific and consistent with an arthropod bite reaction. Bullous reactions to bed bug bites, however, reflect a local cutaneous vasculitis with histology resembling that of Churg-Strauss syndrome.[26] When bed bug infestations are large, anaemia may also be seen on laboratory evaluation, but laboratory investigation is not part of the routine work-up for bed bugs.[11][27][28]

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