Bedbug Bite

Scott M. Souther, M.D.

Basic Information

Definition

A bedbug’s bite is a wound caused by the penetration of the bedbug mouthpiece into the skin as the insect feeds on blood from vessels or extravasated blood from the damaged surrounding tissue. The saliva of the bedbug contains pharmacologically active substances responsible for a spectrum of undesirable skin reactions depending on the individual. The bugs typically feed during times when an individual is at rest and may feed without being detected. Typically feedings take 5 to 10 minutes.

Synonyms

Insect bite
Bedbug Cimex lectularius bite

ICD-10CM CODES
T00.9	Multiple superficial (insect bite) injuries, unspecified

Epidemiology & Demographics

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Traditionally, bedbugs were considered more common in poorer areas, but they are now increasingly found in areas of frequent travel.
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Bedbug infestations may spread among multifamily and institutional facilities with shared walls and are consequently difficult to eradicate.
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Reports of bedbug infestations have increased dramatically in the U.S., as well as worldwide, likely because of the decreased use of pesticides and increased international travel.
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Bedbugs are attracted to carbon dioxide gas and warm bodies.
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Bedbugs do not have a preference for specific age groups, ethnicity, or sex.
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Persons at higher risk include those who have recently stayed overnight in a hotel, dorm room, hospital, or new home.
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Studies have shown increased sensitivity of cutaneous reaction in previous bite victims.

Physical Findings and Clinical Presentation

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Bites typically occur at night on exposed areas of skin, most often the face, neck, arms, and legs.
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The bites are painless and so do not awaken the individual.
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Onset of signs and symptoms of bites can be immediately on awakening or up to 10 days after the bite.
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Firm, purpuric or erythematous macules, urticaria, papules (Fig. 1), or bullae may be present. Bites are often inflammatory and pruritic, although bedbug-naive individuals may be asymptomatic to their first bites.

FIG.1

Pruritic papules after bedbug bites.

From Kliegman RM, et al.: Nelson textbook of pediatrics, ed 19, Philadelphia, 2011, Saunders.
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Bite may have a central hemorrhagic punctum.
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Victim may observe a linear series often consisting of three bites (“breakfast, lunch, and dinner”).
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Bites are typically pruritic.
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The size, degree of itching, and propensity toward vesiculation all increase with repeated bedbug bites.
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Fig. 2 illustrates symptoms and behaviors resulting from bed bug bites.

FIG.2

Distribution of symptoms in 135 Internet reports describing effects of bed bug bites.

From Goddard J, de Shazo R: Psychological effects of bed bug attacks (Cimex lectularius L.), Am J Med 125:101-103, 2012.

Etiology

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The Cimex lectularius species, also known as the common bedbug (Fig. 3), have flat, oval bodies and retroverted mouth parts used for taking blood meals. It feeds on mammals and birds. Cimex hemipterus is a tropical species that bites mostly humans, and hybrid species of the two insects exist. Both generally feed nocturnally on the blood of sleeping humans. They hide in beds, the floor, or furniture crevices during the day and emerge at night. They go through a larva stage (Fig. 4) and have a life span from 4 months up to 1 year. The adult bedbug is wingless and about 5 to 7 mm in length. It has a modified mouthpart for piercing and sucking that usually leaves a bite mark of papular urticarial presentation to exposed areas of skin. Bedbugs have weak appendages for latching on to their hosts and are not usually transported from person to person.

FIG.3

Bedbug.

From James WD, et al.: Andrews’ diseases of the skin, ed 12, Philadelphia, 2016, Saunders.

FIG.4

Bedbug—second-stage larva.

Habif TP: Clinical dermatology: a color guide to diagnosis and therapy, ed 6, Philadelphia, 2016, Elsevier.
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The saliva of the bedbug contains nitrophorin that enables vasodilation, an anticoagulant that interferes with production of coagulation factor Xa, a salivary apyrase that inhibits platelet aggregation, and an anesthetic. Consequently, the host often does not feel the bite until the effects have worn off.

Diagnosis

Differential Diagnosis

Scabies, flea and mite bites, vesicular disorders, delusional parasitosis, dermatitis herpetiformis, pemphigus herpetiformis, ecthyma, drug eruptions

Workup

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Workup begins with history and physical for clinical symptoms and environmental findings suggestive of insect bites.
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Victims should carefully scrutinize the bedroom for signs of bedbug infestation. One may encounter fecal smears or flecks of blood on bed linens, inside furniture cracks and crevices, and behind peeling wallpaper. Bedbugs may travel as far as 20 feet for a meal. Densely infested rooms may also have a distinctive, pungent, soda syrup–like odor.

Laboratory Tests

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No specific tests recommended except for identification of the insect.
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The histology of bedbug bites is similar to other insect bites. Perivascular infiltrate of lymphocytes, histiocytes, eosinophils, and mast cells is seen within the upper dermis. One may also observe collagen bundles with interstitial eosinophils, dermal edema, and extravasated erythrocytes.
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Hypersensitivity to bedbug salivary proteins may be tested via intradermal allergy skin testing.
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Skin biopsy results are nonspecific and are not helpful in making the diagnosis.

Imaging Studies

None

Treatment

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Specific treatment of bedbug bites is often not necessary. Bites may self-resolve within a week for milder cases and a few weeks for more severe cases. Treatment regimens are based on resolving symptoms of the bites, mainly pruritus.
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To prevent infection, avoid scratching the area.
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Topical glucocorticoids or systemic antihistamines are appropriate in patients with severe pruritus from the bedbug bite.
1. 1.
  
  Triamcinolone cream 0.1%; apply thin film to affected areas bid
2. 2.
  
  Chlorpheniramine 4 mg PO at bedtime (adults), 2 mg PO at bedtime (children)
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Insecticides may be effective in eradicating the bedbug, but growing resistance has been seen and multi-insecticide therapy is recommended.
1. 1.
  
  Use permethrin spray for clothing and bedsheets or bed nets.
2. 2.
  
  Diethyltoluamide (DEET): Be wary of toxic levels in children when used at high concentrations.
3. 3.
  
  Deltamethrin and chlorfenapyr are two common insecticides used.
4. 4.
  
  Please consult a pest control professional for safe eradication.

Nonpharmacologic Therapy

Vacuuming is effective in removing bedbugs but does not remove the eggs. Wash bedsheets and clothing in hot water with detergent with at least 20 minutes in a dryer. Bedbugs have a high thermal death point of 45° C and also may survive at temperatures as low as 7° C. Some companies perform a treatment in which the room is heated above 50° C, which is a lethal temperature for all stages of a bedbug’s life cycle. Coating bedposts with antifriction or adhesive substances such as petrolatum or duct tape may hinder bedbugs from gaining access to the bed.

Acute General Rx

Immunologic response is dependent on immunocompetence and individual sensitivity to the salivary components of the bedbug bite. Often, patients with papular urticaria have IgG antibodies to specific bedbug proteins. IgE antibodies may also mediate bullae formation. Anaphylaxis and death from bites is rare but documented in literature.

Disposition

Patient may resume normal activity and lifestyle. Travelers should inspect their clothing and suitcases before returning home.

Bedbugs as Potential Vectors

The bedbug has been studied extensively as a potential vector for human pathogens such as HIV, hepatitis B, hepatitis C, and Chagas’ disease. To date, there is no evidence of transmission from an infected bedbug to a human.

Pearls & Considerations

Comments

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Bedbugs are an increasing source of anguish and frustration for humans, and clinicians should evaluate for signs of stress and depression.
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A combination of chemical and physical intervention is often necessary for complete eradication. All hiding areas must be carefully inspected and cleaned. Treatment may include pesticides, laundering, heat, freezing, vacuuming, and hiring a professional service to eradicate bedbugs.

Ferri – Bedbug Bite