By the early 1940s, bed bugs were mostly eradicated in the developed world, largely by the broad spread use of DDT (dichloro-diphenyl-trichloroethane). But since its ban in the U.S. in 1972 and its global ban by the 2001 U.N. Stockholm Treaty, along with the increase in international travel, bed bugs have made a resurgence. The result: Healthcare providers in the U.S. have seen a similar jump in bed bug bites and related conditions.
Bed bugs are parasitic insects of the cimicid family that feed exclusively on blood. Adult bed bugs are reddish-brown in color, flat, oval shaped, wingless and range from 3-7 mm. Immature bed bugs are much smaller and may be light yellow. They have a pyramid-shaped head with prominent compound eyes, slender antennae and a long proboscis tucked underneath the head and thorax. After a blood meal, the bugs may increase in length by 30-50% and in weight by 150-200%.2
Though the cimicid family includes insects that feed on the blood of other animals, such as bats, the term bed bugs most commonly refers to members of Cimex lectularius, which prefers to feed on human blood. The term also refers to their preferred habitat of warm houses, specifically near their food source, and their nocturnal feeding patterns.
Known as human parasites for thousands of years, they are incredibly well-adapted opportunists. Human dwellings give bed bugs a perfect combination of a reliable food source and convenient, cooler harborage. Bed bugs thrive at a temperature between 60-70º F, but they can survive a wide range of temperatures and atmospheric compositions. Thus, rather than live directly on the too-warm host, it feeds and then returns to the cooler, dark hiding places that it favors.
More recent research indicates that consistently cooler temperatures may expand the lifespan of bed bugs. Adult bed bugs will enter semi-hibernation below 61º F and can survive from weeks to months, but they also can survive for at least five days at -10º C (14º F) and 15 minutes of exposure to -32º C (-26º F). Adults die of heat only after the fairly high temperature of 113º F and all stages of life are killed by 7 minutes of exposure to 46º C (115º F).3
Their slim flat bodies allow them to fit into the smallest of spaces and lay in wait for easily up to a year, even without a blood meal.2 They congregate on bed or seating structures, in mattresses, pillows and bedding, and in dark hiding nooks on adjacent furniture and walls, including under baseboards and behind socket plates. They are attracted primarily to CO2 and warmth, which allows them to locate their sleeping hosts in the dark.4
Bed bugs usually are spread by being transported with people's belongings as they travel. The bed bugs travel in the seams and folds of luggage, overnight bags, folded clothes, bedding, furniture and anywhere else where they can hide. The bugs easily move from object to object without a human host present, and so objects become fomites that can then carry the bugs to access new human hosts. Examples include shipping containers, storage units and moving vans, besides actual dwelling places and their contents.5 In addition, bed bugs can be transported on the fur of pets and other animals, presumably the fur allowing the bug to be suspended and somewhat protected from the animal's body heat. Bed bugs also may migrate from one apartment or hotel room to another through holes in walls, in ceiling rafters, water pipes or gutters.
Life Stages & Breeding
Though they are not rapid breeders when compared to many other pests, a bed bug population left untreated can become a critical problem in a matter of months.6 Adult bed bugs have an average life span of six to 12 months. Bed bugs have six life stages (five immature nymph stages and a final, sexually mature adult stage). They will molt their skins at each stage much like a crab does, discarding their outer shells which are clear, empty exoskeletons.
Bed bugs must molt six times before becoming fertile adults and must take a blood meal to complete each molt. Each of the immature stages lasts approximately a week, depending on temperature and the availability of food, and the complete lifecycle can be completed in as little as two months.
Fertilized females with enough food will lay three to four eggs each day continually until the end of their lifespans (about nine months under warm conditions), possibly generating as many as 500 eggs in that time.
Fertilization is done by traumatic insemination, in which the male uses his hypodermic genitalia to inject sperm into the female's abdomen, which then make their way to the ovaries.7 Females can well-tolerate one wound, but subsequent wounds increase her risk of infection. As a result, fertilized females are likely to hide away from other bugs to avoid the males, which can make her harder to find and eradicate.8 She then can continue an infestation with subsequent generations.
On the Move
Bed bugs move by crawling and climbing surfaces rough enough to gain purchase such as walls or furniture legs. They cannot jump or fly but can crawl on some vertical surfaces and fall onto the host site, such as crawling up a wall and falling onto an adjacent bed.9 Fortunately, they tend to congregate around one host site and do not usually crawl several feet (what for their scale would be a great distance) into other rooms; they must be carried by some other vector. For this reason, it is important to avoid using over-the-counter aerosol pesticides for bed bugs as it gives them an incentive to scatter to avoid the gas, spreading infestation sites.10 Thus, with care, it is feasible to limit infestation to only one site in a home.
Bed bugs are mainly active at night but are not exclusively nocturnal. They come out to feed when humans are largely immobile, usually without their hosts noticing at the time. A bed bug pierces the skin of its host with its entire maxillary and mandibular bundle called a stylet fascicle, rostrum or "beak."
The stylet is comprised of elongated maxillae and mandibles, the former connected at their midline and a section at the centerline forms a large food canal and a smaller salivary canal. The bed bug uses tiny teeth on the mandibular stylet tips to chew through tissue to access a blood vessel. The pressure from the blood vessel itself fills the insect with blood in three to five minutes. The bug then withdraws the stylet bundle from the feeding position and folds the entire unit back under the head and returns to its hiding place.
It takes five to 10 minutes for a bed bug to become completely engorged with blood. In all, the insect may have spent less than 20 minutes in physical contact with its host and will not attempt to feed again until it has either completed a molt or, if an adult, has thoroughly digested the meal.7
Implications for Healthcare
As repulsive as bed bugs are, they do not present the health threats that do many other insects humans regularly encounter, such as mosquitos, ticks and cockroaches. Of these examples, bed bugs are uniquely dependent on humans as they are one of the few parasites that feed almost exclusively on human blood, and this may be why they have evolved to seemingly not cause any diseases in human hosts. "They may bite the hand that feeds them, but they seem to do so without jeopardizing their food source."3 To date, though bed bugs have been found to harbor many infectious agents within their saliva ducts and GI tracts, there is no evidence of transmission of disease by bed bugs.2
Absent direct transmission of disease, the salivary proteins left in the bites can later elicit allergic reactions in the host. Prevalence of bed bug allergy is unclear, as one study of 900 subjects indicated less than 5% of subjects developed allergy by second exposure, another indicated as high as 30%; other studies note significant escalation of allergic response with subsequent exposures.3 This is especially significant in that lab environment studies are unlikely to recreate the frequently repeated exposure that happens in a home infestation situation.
Diagnosis of the bites involves both finding bed bugs and the occurrence of compatible symptoms. Most people may have mild pruritus and possibly urticaria, with minimal marking of the skin, which, if not abraded, resolves within a week. People are more likely to seek medical attention if the bite marks are more obvious, often in clusters or lines of 2-5 mm pruritic maculopapular erythematous lesions; if the lesions itch severely; or if abrasion from scratching results in more severe rashing or secondary infection.
Secondary infection may result in folliculitis, cellulitis or an eczematoid dermatitis. Reactions as severe as angioedema and asthma only rarely have been documented. One recent article cites two cases of severe anemia in an elderly couple living in an infestation, but this is seemingly novel.
Primary care interventions focus on managing symptomatic allergy and infectious symptoms, though there is little specific evidence base. Primary care providers should be sure to reassure patients that though bed bugs are repulsive and annoying, they do not present any significant health threat as long as these symptoms are managed.
Pruritus can be managed with topical application of over-the-counter or prescription antipruritic agents. Intermediate-potency corticosteroids such as triamcinolone may be helpful. Infections can be managed with topical mupirocin or systemic antibiotics. Systemic reactions to bed bug bites are treated as insect-induced anaphylaxis, with treatment including intramuscular epinephrine, antihistamines and corticosteroids.
The more common severe effects of bed bug infestation are more psychological, as the intense itching can cause significant distraction, distress, agitation and anxiety, at least in part by the disgust evoked at the idea of a parasite feeding while one is vulnerably sleeping. Insomnia is common both due to actual itching and anticipation of more bites during sleep.3 Primary care providers should offer compassionate support for the patient's distress, reassurance of low health risk, and reminders to as much as possible avoid further trauma and contamination to the bites by scratching.
Cases of delusional parasitosis after suggestion of bed bug infestation have been documented. This is when a person becomes irrationally convinced of bed bug infestation without evidence and may present with lesions and rashing from scratching behaviors. For such individuals, the preoccupation with confirming the diagnosis often prompts them to submit multiple skin, lint or dust samples, and seek out assistance from multiple healthcare providers, entomologists and exterminators. They often are fairly fixed in the delusion and resistant to hearing negative findings. Furthermore, the compulsion to eradicate the perceived infestation can lead to disruptive and time-consuming cleaning behaviors, trying multiple unvetted remedies that may have their own complications, and accidental toxicity from over-application of dangerous pesticides.
Primary care providers should refer such individuals to a mental health professional, as well as any patient having significant sustained anxiety, insomnia and distress from infestation symptoms, as a severe infestation can take months to completely clear without recurrence.
Prevention of bed bug bites is best achieved with avoidance, because no repellents for the insects have been demonstrated conclusively to be effective. The mosquito repellant oil of lemon eucalyptus may help, but there is only limited evidence for this.3
Bed bugs and their fecal matter are easily visible. When sleeping in hotels or other unfamiliar environments, a prudent approach for preventing bites is to check the premises for bed bugs or their excreta. Important sites to inspect include mattress cords, cracks and crevices in box springs, and the back of headboards.
Items purchased at garage sales and resale shops, especially mattresses, box springs and bedding, should be carefully inspected for bed bugs before they are brought into homes because they may initiate an infestation. Several municipalities and states, including San Francisco, New York, Arizona, Alabama and Maine, now have disclosure laws that require landlords to notify potential tenants if bed bugs have been found on their property, and remedies attempted to eradicate them and when.
Steps necessary for bed bug eradication include proper identification of the insect; education of people involved; thorough inspection of infested and adjacent areas; implementation of chemical and nonchemical control measures; and follow-up to evaluate the success of eradication.
As stated earlier, DDT was previously considered an effective remedy for bed bug infestation, but its residual and downstream toxic effects led to its global ban. Without it, exterminator companies tend to use pyrethroids, dichlorvos and malathion, but no good data support their full efficacy and resistance to them has been increasing over time. In addition, there are legitimate concerns regarding potential negative health effects from their use.
Currently, several pesticides are undergoing evaluation for control of bed bugs. In general, the products have not performed as well with bed bugs as they have against other pests and eradication often requires nonchemical tactics as well.3 Boric acid works mainly as a stomach poison. Since bed bugs survive on blood only, they would not ingest boric acid.
Cedar oil has been widely advertised as bed bug deterrent or pesticide, but as of September 2012, the Federal Trade Commission had filed deceptive advertising charges against several companies making hyperbolic claims advertising a cedar oil bed bug remedy. The commission found several aspects of the claims were false, including the companies having scientific evidence of the efficacy of their product.
Nonchemical methods for bed bug control include vacuuming, heat or steam treatments, mattress and box spring encasements, and discarding furnishings such as mattresses and box springs. Discarding mattresses and box springs is sometimes recommended by pest control personnel or public health authorities, yet it is financially burdensome.3 All washable bedding and clothing should be washed and or dried in heat above 115º F for at least 15 minutes to kill all adults, larvae and eggs. Non-washable cloth items such as pillows and furniture should be either dry or thoroughly steam cleaned, as these methods are also lethal to the bed bugs at all stages.,21
Diatomaceous earth is another non-chemical intervention as it is inert and non-toxic to humans and pets. Though it feels fairly fine and smooth to human fingers, it is actually quite coarse on a microscopic level and acts as a mechanical excoriator to the bugs' waxy underbellies as they crawl across it. The excoriation leaves them vulnerable to dehydration which can take up to a week to be lethal. Diatomaceous earth is to be spread as a barrier between host and hiding places, such as on floors around the bed's immediate perimeter, along possible crawl routes from the host site to all possible hiding places.
Other methods focus on creating physical obstacles between the host site and hiding places, such as setting legs of the bed in smooth plastic cups or coating them in petroleum jelly the bugs may not be able to scale. Placing bed legs in plastic containers filled with water with a drop of dish detergent or oil may work as well.
Encasement is another form of barrier. Mattresses and box springs should be covered with encasements (similar to those used for dust mite allergies) that will not allow any remaining bugs to feed through the material or escape its confines. Encasement in air-tight plastic may be necessary for other objects such as books nearby the site of infestation, and the bugs can hide in tiny nooks and crannies, and as stated above, wait for up to six to 12 months for a blood meal. By keeping the bugs sealed in for that duration, they are eventually starved.
For all of the bed bug eradication methods, persistence and patience are key. Once an infestation is established, no method will quickly eradicate all threats of bites and recurrence of infestation. Often multiple measures must be used at once, and usually repeatedly.
In the meantime, patients can provide ways that they can live in their homes with their belongings and minimize bites until the infestation dies down. Primary care providers are well-advised to counsel patients to have patience with the process, to help make any related health threats manageable and to provide ongoing support. The problem is eradicable with diligence and a "tincture of time."
1. Environmental Protection Agency. DDT (dichloro-diphenyl-trichloroethane). http://www.epa.gov/history/topics/ddt
2. Goddard J, deShazo R. Bed bugs (Cimex lectularius) and clinical consequences of their bites. JAMA. 2009;301(13):1358-1366.
3. Harrison RL, Lawrence B. Pulling back the sheets on the bed bug controversy: research, prevention and management in hospitals and long-term care facilities. www.ahe.org/ahe/content/orkin/ahe-bedbug-white-paper.pdf
4. Wang C, Gibb T, Bennett GW, McKnight S. Bed bug (Heteroptera: Cimicidae) attraction to pitfall traps baited with carbon dioxide, heat, and chemical lure. J Econ Entomol. 2009;102(4):1580-1585.
5. New York City Department of Health and Mental Hygiene. Simple ways to avoid ways to avoid bed bugs during moving and storage. http://www.nyc.gov/html/doh/bedbugs/downloads/pdf/bed-bugs-moving.pdf
6. Benoit JB, Lopez-Martinez G, Teets NM, et al. Responses of the bed bug, Cimex lectularius, to temperature extremes and dehydration: levels of tolerance, rapid cold hardening and expression of heat shock proteins. Med Vet Entomol. 2009;23(4):418-425.
7. Reinhardt K, Siva-Jothy MT. Biology of the bed bugs (Cimicidae). Annu Rev Entomol. 2007;52:351-374.
8. Morrow EH, Arnqvist G. Costly traumatic insemination and a female counter-adaptation in bed bugs. Proc Bio Sci. 2003;270(1531):2377-2381.
9. New York State Integrated Pest Management Program. FAQ list for bed bugs. http://www.nysipm.cornell.edu/whats_bugging_you/bed_bugs/bedbugs_faqs.asp
10. Jones SC, Bryant JL. Ineffectiveness of over-the-counter total-release foggers against the bed bug (Heteroptera: Cimicidae). J Econ Entomol. 2012;105(3):957-963.
11. Price JB, Divjan A, Montfort WR, et al. IgE against bed bug (Cimex lectularius) allergens is common among adults bitten by bed bugs. J Allergy Clin Immunol. 2012;129(3):863-865.e2.
12. CDC. Bed bug FAQs. http://www.cdc.gov/parasites/bedbugs/faqs.html
13. Paulke-Korinek M, Szell M, Laferl H, et al. Bed bugs can cause severe anaemia in adults. Parasitol Res. 2012;110(6):2577-2579.
14. Goddard J, deShazo R. Bed bugs (Cimex lectularius) and clinical consequences of their bites. JAMA. 2009;301(13):1358-1366.
15. Doggett SL, Russell R. Bed bugs - What the GP needs to know. Aust Fam Physician. 2009;38(11):880-884.
16. Shmidt E, Levitt J. Dermatologic infestations. Int J Dermatol. 2012;51(2):131-141.
17. Hinkle NC. Delusory parasitosis. American Entemologist. 2000;46(1):17-25.
18. National Pest Management Association. State Bed Bug Specific Laws & Rules as of August 26, 2011. http://www.pestworld.org/media/3309/statebedbuglawsasofaug262011_2_.pdf
19. South Carolina Department of Health and Environmental Control. Bed bugs. http://www.scdhec.gov/environment/envhealth/pests/bed-bugs-get-rid.htm
20. Federal Trade Commission. FTC takes action against companies marketing allegedly unproven natural bed bug and head lice treatments. http://ftc.gov/opa/2012/09/cedarcidermb.shtm
21. Pereira RM, Koehler PG, Pfiester M, et al. Lethal effects of heat and use of localized heat treatment for control of bed bug infestations. J Econ Entomol. 2009;102(3):1182-1188.
22. Benoit JB, Phillips SA, Croxall TJ, et al. Addition of alarm pheromone components improves the effectiveness of desiccant dusts against Cimex lectularius. J Med Entomol. 2009;46(3):572-579.
23. Columbus Public Health. Bed bug quick relief guide for tenants and homeowners. http://publichealth.columbus.gov/uploadedFiles/Public_Health/Content_Administrators/Press_Room/Bed%20Bug%20Relief%20Guide.pdf
24. Meek F. Ban bed bugs. How to prevent and identify infestations. Behav Healthc. 2008;28(4):28.
Anna Davis has more than 27 years of experience working in mental health, with a focus on health education and patient empowerment.