When Bed Bugs Bite
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Mark K. Huntington, MD, PhD When bed bugs bite Sioux Falls Family Medicine Residency Program; Department of Family Treating bed bug bites is straightforward; helping Medicine, University of South Dakota Sanford patients control and even prevent future infestations is School of Medicine, Vermillion, SD another matter. Here’s how you can help. mark.huntington@usd. edu The author reported no ed bugs, Cimex spp, are a re-emerging public health potential conflicts of interest relevant to this article. Practice problem in the United States. First recorded by the recommenDations B ancient Greeks,1 bed bugs have plagued societies for › Provide symptomatic relief centuries. In the United States, infestations peaked in inten- for bed bug bites with antihis- sity in the 1920s and 1930s, then were largely eliminated as tamines or corticosteroids. C a significant concern after World War II, thanks to synthetic, › Advise patients experienc- residual pesticides.2 By the mid-1990s, bed bugs were so un- ing an infestation to consider common that specimens could not be obtained for medical the CDC’s recommended education purposes.3 integrated pest manage- That has all changed. ment program (eg, heat Although commonly perceived as disproportionately treatment, vacuuming, affecting the underprivileged,4 bed bugs are equal- nonchemical pesticides) to opportunity pests, infesting the most posh hotels, retailers, increase the likelihood of and theaters.5,6 According to one news report summariz- successful extermination. C ing data from a national pest control firm, US cities with the strength of recommendation (SOR) highest infestation rates are, in descending order: Cincinnati, A Good-quality patient-oriented Columbus, Chicago, Denver, Detroit, Washington DC, New evidence York, Philadelphia, Dayton, and Baltimore.7 Although bed B Inconsistent or limited-quality patient-oriented evidence bugs are not known to transmit infectious diseases, they are C Consensus, usual practice, responsible for significant dermatitis, allergic reactions, and opinion, disease-oriented evidence, case series psychological distress. Bed bug biology and behavior The bed bug life cycle has 7 stages. All but the egg stage re- quire blood meals before the arthropod can molt to the next stage. Bed bugs are attracted to their hosts by body heat and exhaled carbon dioxide, and they feed only through the skin. This makes baiting and trapping challenging, although it’s a common extermination strategy for other domestic pests. Also, unlike cockroaches, flies, or other pests, bed bug infesta- tions are not associated with hygienic deficiencies. Improved housekeeping does not significantly affect their populations; bed bugs feed on household inhabitants, not their spilled or improperly stored food. However, clutter does increase their chances of finding refuge. Interestingly, researchers recently discovered that bed bugs are themselves hosts to the endosymbiotic bacterium, 384 The Journal of family PracTice | July 2012 | Vol 61, no 7 Wolbachia.8,9 This genus is found in many more likely due to scratching. Bed bug bites invertebrates and appears to be essential for are allergenic, and they have also been impli- normal bed bug fertility and reproduction. cated in asthma exacerbations and even ana- Targeting the bacteria may inhibit the ability phylaxis.10,11 In severe infestations, anemia of bed bugs to breed—something we’ll dis- from the extensive blood-meals can occur.12 cuss a bit later. Experimental studies have found that >45 human pathogens—ranging from viruses to methicillin-resistant Staphylococcus au- clinical assessment reus to helminths—can survive ingestion by Patients with bed bug bites complain about bed bugs, but none have shown pathogens intensely pruritic lesions. These are typically to be transmitted to humans by bed bugs.11 erythematous and indurated and may be hem- Fortunately, bed bugs do not appear to be orrhagic. The pattern of bites is often linear, competent as vectors, although prospective and 3 bites in a row are common, sometimes studies are ongoing.13 In addition to allergic referred to as “breakfast, lunch, and dinner.” manifestations, bed bug bites have been as- Patients typically have no recollection of being sociated with significant, even incapacitating, bitten, as bed bugs feed on sleeping hosts, and psychiatric problems such as anxiety, obses- their bite is usually painless. sion, and depression to the point of suicide.14 z clues to bed bugs as the source. Sca- the cDc bies mites also cause linear pruritic lesions, recommends but bed bug lesions differ in appearance and treating symptoms and cause an integrated distribution. Scabies lesions are subtle, ap- Management of bed bugs consists of symp- approach pearing as burrows and excoriations, in con- tomatic treatment of the bites and elimina- to fighting trast to the more prominent erythematous tion of the infestation—treating both patients infestation: 15 papule seen with bed bugs and other arthro- and their environments. removing clutter, pod bites. Scabies tend to occur in skin folds, sealing cracks finger webbing, genitals, and areas where treating patients and crevices, clothing is tight, such as beltlines. In contrast, Treating bed bug bites mainly involves pro- applying heat bed bugs tend to attack easily accessible, ex- viding symptomatic relief with antipruritic treatment, posed areas. Areas covered with loose cloth- agents (antihistamines, topical or oral cor- vacuuming, ing are less affected, and areas covered by ticosteroids, over-the-counter topical an- and using 16 tight clothing are essentially spared. Multiple esthetics). When, rarely, a bite becomes pesticides. members of the household are often affected. infected, antibiotics may be indicated. Ad- z Flea bite? Bed bug bites may be virtu- dress psychological distress associated with ally indistinguishable from those of other an infestation. Counseling with cognitive be- arthropods such as fleas, spiders, or mosqui- havioral therapy is effective most of the time, toes. While the linear 3-bite pattern may although some cases may warrant short-term suggest bed bug exposure, it is not patho- psychopharmacotherapy. gnomonic. Capturing the arthropod or find- Symptomatic relief will be short-lived, ing evidence of infestation (discussed in a bit) however, without remediation of the underly- is needed to confirm a bed bug as the source ing infestation. If the bugs remain, the biting of the bite. will continue. The etiology of pruritic papules is broad. Besides arthropod bites, include conditions treating the environment such as papular eczema, papular pruritic Every object and location in which bed bugs eruption, and eosinophilic folliculitis in the may have taken refuge must be treated. The differential diagnosis. first step in eradicating an infestation is to find it. In light infestations, evidence may be Potential for complications limited. However, they are dirty bugs. Sig- As with any break in the skin, secondary in- nificant amounts of litter, including molted fection is a risk, although it is rarely a com- exoskeletons, dark feces, and eggs, are found plication of the bite. If infection occurs, it is wherever there is an infestation. These signs JfPonline.com Vol 61, no 7 | July 2012 | The Journal of family PracTice 385 TABLe Xenointoxication with ivermectin has proven effective against several ectoparasite infestations24-28 in vitro research has shown that bed bugs are also susceptible to this class of antiparasitic drugs. ectoparasite condition ivermectin dosing Sarcoptes scabiei Scabies 0.2 mg/kg, single dose Pediculus capitis head lice 0.2 mg/kg every 10 days x 2 doses Pediculus corpora Body lice 0.2 mg/kg every 7 days x 3 doses of infestation may be found on mattresses z Desiccant dusts such as silica gel and or box springs, or in the bottom of bureau diatomaceous earth, applied along the base- drawers and the corners of rooms. Anywhere boards and the back of bookshelves, have just out of reach of the vacuum cleaner can also demonstrated efficacy.23 As with chemi- harbor their detritus. Some success has been cal pesticides, it is important to follow direc- reported using bed bug detectors/monitors.17 tions when using desiccant dusts to minimize Bed bugs are Bed bug-sniffing dogs have been trained and potential health hazards. good at hiding employed in both identifying infestations z the cDc recommends a comprehen- and can survive and monitoring the efficacy of eradication sive, integrated pest management program for up to a year interventions. to control bed bugs. This program includes a without feeding. A number of extermination methods number of methods, such as removing clut- have been used. The most commonly used ter and sealing cracks and crevices where chemicals are permethrins, the same agents bed bugs take refuge, applying heat treat- that have proven effective in antimalarial bed ment, vacuuming, using nonchemical pes- net programs. This agent is applied to the en- ticides, and cautiously applying effective vironment, not to the patient. Generally, at chemical pesticides.17 An approach such as least 2 applications are required. Although this is labor- and time-intensive, and can be as recently as 1990 no bed bug resistance to costly. permethrin had been reported,18 there is now Given the inadequacies of current strat- widespread resistance.19 Efforts at developing egies in controlling infestations, new ap- new agents are progressing. proaches are needed. One such approach Besides resistance, toxicity to humans