Over the past 20 years, bed bug infestations have reemerged in clinical settings.1 Bed bugs are hematophagous arthropods in the Hemiptera order of the Cimicidae family. These insects are an off-white color as nymphs and are reddish-brown in the latter stages of their life cycle. The 2 species of bed bugs associated with humans are Cimex hemipterus (inhabiting tropical and subtropical climates) and Cimex lectularius (inhabiting mainly temperate climates).2 Bed bug bites mainly cause a pruriginous maculopapular rash but, unlike other arthropods, are not known to act as vectors for pathogens. Despite this, bed bugs can cause significant disruption to patient care, produce fear of contagion among staff and patients, and result in expensive procedures for containment and control of spread.2-5
A 73-year-old homeless man recently had received a diagnosis of cutaneous T-cell lymphoma with Sézary syndrome (T4N3B1M0). His chief concern was a pruritic dry rash of the bilateral upper extremities, which had spread progressively to his face, trunk, and legs. Peripheral blood flow cytometry results showed atypical T lymphocytes (43% predominance). Findings of a positron emission tomography plus computed tomography (PET/CT) scan showed hypermetabolic activity in the neck, bilateral subpectoral, axillary, and inguinal lymph nodes. Skin punch biopsy showed atypical lymphocytic infiltration. Biopsy of an epitrochlear lymph node demonstrated involvement with T-cell mycosis fungoides. He had been treated previously with bexarotene and photopheresis without significant improvement. He then had begun treatment with romidepsin. After the first 2 doses of the first cycle, the patient’s pruritus and rash resolved. He had no significant adverse reactions.
During his visit for the second cycle of treatment with romidepsin, he presented with new-onset pruritic erythematous papules on the upper arm and upper back. (Figures 1 and 2 depict a different patient who had similar lesions.) Small red insects, soon to be identified as C lectularius, were found on the patient’s bed (Figure 3).
Figures 1 and 2. A different patient presented with new-onset pruritic, erythematous papules on the upper arms and upper back, similar to our patient’s lesions
The nurse caring for the patient believed that she had received bites, as well. The patient initially was in denial about having bed bugs and expressed anger and embarrassment when informed of the finding. The bed bugs had been brought to the hospital by the patient, and the truck cab in which he slept also was infested and was later fumigated.
Through collaboration and consultation with social workers, nurses, hospital infection control specialists, and the state health department, a comprehensive protocol was developed that successfully prevented a bed bug infestation of the staff and facility. Measures taken at the clinic included having the patient shower and change into disposable scrubs, along with double-bagging of all his belongings. Staff involved directly in the care of the patient wore gowns and gloves. This allowed the patient to successfully complete 7 cycles of romidepsin in a busy outpatient infusion center.
Figure 3. Clinical specimen of a bed bug (photo courtesy Ramon Sandin, MD).
At the time of the patient’s last visit, he was found to be free of bed bugs. The treatment facility made the decision to dispose of some of the furniture used in the care of the patient (eg, the infusion chair).
Clinical Manifestations of Bed Bugs
Bed bugs harbor in dark recesses such as bedclothes, mattresses, springs, bedframes, cracks, crevices, and wallpaper.1 Because these arthropods do not possess wings, their movement typically occurs via direct physical contact with surfaces. Their spread occurs principally via 2 mechanisms: active transmission and passive transmission. Active transmission occurs by bed bugs crawling across neighboring areas. Passive transmission, however, occurs by transfer of bed bugs via fomites (eg, clothes, bags, linens, furniture). Evidence also suggests that bed bugs are capable of dispersing by small air currents and by static electricity.6 Because of their ability to survive up to 5 months without feeding, leaving infested rooms vacant is not an effective solution in resolving a bed bug infestation.7
Bed bugs are night feeders of humans, with painless bites attributed to their needle-like stylets that penetrate the skin. Multiple bites often exhibit characteristic lined and curved patterns on exposed areas of the body from either a single bed bug probing to find a productive capillary bed or many bed bugs feeding along a zone of exposed skin. For individuals who do not experience a reaction from the bed bug bite itself, the area appears as a small punctum with no surrounding reaction.2
The severity of cutaneous reactions from bed bug bites varies between individuals. Some individuals develop no reaction, although this may depend on previous exposures.8 In individuals who do mount a reaction against bed bug bites, pruriginous macules or papules develop, usually within 48 hours. These reactions manifest frequently as 2- to 5-mm pruritic, erythematous papules or wheals with a central hemorrhagic punctum. These lesions tend to be intensely itchy.8 Bed bug bites also can appear as papular urticaria, and individuals with them may develop immunoglobulin G (IgG) antibodies against C lectularius.9,10 Skin reactions that mimic urticaria produce edema in the upper dermis, as well as a perivascular inflammatory infiltration with lymphocytes, eosinophils, and mast cells.11,12 Occasionally, more-severe bullous lesions can develop with intraepidermal edema, subepidermal edema, and a mixed dermal inflammatory infiltrate.13-16 One case report described bullous lesions with histopathologic features consistent with cutaneous vasculitis.15 Occasionally, systemic allergic reactions or systemic manifestations may occur, such as iron-deficiency anemia.3,17
Bed Bugs as Vectors for Pathogens
Within the medical community, there has been debate as to whether bed bugs are capable of acting as vectors of disease to humans.18 Among the human pathogens that have been detected in bed bugs are hepatitis B virus,19,20 hepatitis C virus,20 Trypanosoma cruzi,21 HIV,22,23 and methicillin-resistant Staphylococcus aureus.24,25 Although these pathogens can exist within the bed bug and transmit diseases to other animals, no evidence exists to confirm that bed bugs are capable of acting as vectors of these diseases to other humans.26
The successful diagnosis of bed bug infestation must be confirmed by physical detection of the insects. Although the linear feeding pattern can be a reasonable indicator, this feeding pattern does not occur in all cases, such as when few bed bugs are present. The detection of bed bugs can be accomplished by way of visual inspection, isolation with physical traps baited with chemical attractants, or through the action of bed bug–detection dogs.27 Other signs can include molted cast skins of bed bugs, or feces or blood on bedding, mattresses, or wallpaper.28,29 Skin biopsies for detection of bed bug bites have proven to yield nonspecific results and are unnecessary.
When diagnosing bed bug infestation, it is important to consider the differential diagnosis for other arthropod bites that result in pruritic papules. Bites of bat bugs or swallow bugs, scabies, fleas, Cheyletiella mites, and other mite species can be mistaken for bed bug bites. Dermatitis herpetiformis is also included in the differential diagnosis. This rash is characterized by pruritic inflammatory papules and vesicles on the forearms, knees, scalp, or buttocks and can be confirmed via biopsy with direct immunofluorescence studies.
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