Published on 16/03/2015 by admin
Filed under Dermatology
Last modified 16/03/2015
This article have been viewed 1236 times
Whitney A. High and Glen R. Needham
Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports
Human bed bugs (Cimex lectularis) are insects that have afflicted mankind for at least 3000 years. There is evidence that human bed bugs were derived from bat bugs, which adapted from bats to humans when our ancestors inhabited caves. Bed bugs require a blood meal to complete their lifecycle, and this requisite blood meal is acquired by biting sleeping humans. While not all persons react to bed bug bites, the bite can elicit an allergic reaction, creating pruritic, erythematous papules that are often excoriated, and even secondarily infected.
Bed bug infestations were once ubiquitous. In the late 1940s and early 1950s widespread use of the insecticide dichlorodiphenyltrichloroethane (DDT) brought bed bug infestations to a nadir in the developed world. Following a worldwide ban on DDT, and with emerging resistance to this and other insecticides, bed bug infestations have resurged into prominence.
Most bed bugs bite during the early morning hours, just before dawn, and most bed bugs lie in close proximity to the sleeping quarters. Adult bed bugs are typically 5–7 mm in length (just less than 0.25 inch), with females being slightly larger than males.
While bite of the bed bug is painless, an allergic reaction may occur in some individuals, yielding a pruritic, erythematous papule. Bed bug bites tends to occur on exposed surfaces, such as the extremities or head/neck. The insect will not typically venture beneath bedding or bed clothes. A linear orientation to the bites is common.
Because the insect does not reside or lay eggs upon humans, ultimate treatment focuses upon detection and eradication of the household infestation.
Once an infestation has been confirmed, an extermination program should be commenced. Insecticides, growth regulating agents, and destructive modalities may be employed to kill adults, progeny, and eggs. Many authorities believe that safe and successful eradication of infestations requires professional assistance, although many purveyors of such materials may contest this assertion.
The use of insecticides in the US is regulated by the Environmental Protection Agency. DDT was once a premier insecticide for use against bed bugs, but the extended residual effect of the insecticide resulted in environmental damage; ultimately its use was banned. Resistance among bed bugs, first to DDT, but also later to malathion, may be an issue with its re-emergence as a scourge as well.
Most recently, the pyrethroid class of insecticides (e.g., deltamethrin) have emerged as a widely used substance for controlling bed bug infestations, but resistance problems are mounting for these agents as well.
There is great interest in the use of temperature extremes to eradicate bed bug infestations. For example, steam may be utilized to sterilize a mattress or other materials for which insecticides are inappropriate, but the target temperature of 160–180°F must be reached over the entirety of the surface.
Commercial whole room (or whole home) heating systems utilizing propane heaters and fans to develop convective cycles have been developed. Most of these systems are based on a target temperature of around 113°F, to be held for 15–60 minutes. This temperature is less than the laboratory-based thermal death point of 118°F, yet these treatments have proven successful, apparently due to the powerful convection currents created within the heated room that desiccate the insects.
Comparatively more simplistic measures, such as the use of impermeable mattress casings to isolate the bed bugs within the mattress from those on the surface, are widely advocated.
On the horizon, entomologists and other experts are seeking new ways to gain control over the epidemic of bed bugs. In this regard, the manipulation of insect pheromones is gaining interest. Bed bugs use pheromones to aggregate, thereby raising the likelihood of both successful mating, and also increasing local humidity to avoid desiccation. In this regard, the blocking of effective signaling may have disastrous effects upon a colony.
As all human-based treatments presently available for bed bugs are based on the symptomatic care of bite reactions, the successful detection of infestations is vital to employment of external eradications measures.
Skin reactions to bed bug bites are due to an allergic reaction to the saliva leaked during feeding. Sensitization is not universal, and sometimes an individual will not react to bed bug bites at all, meaning a query for others affected in a household may or may not be of significance.
Bed bug bites typically manifest as an erythematous wheal, followed by a firm, reddish papule, sometimes with a small central hemorrhagic punctum. Papulonecrotic forms have been described as well. The bites are often both inflammatory and pruritic, and are often present on exposed areas of the body, such as the head, neck, arms, legs, and shoulders. Bed bug bites rarely occur in the axillae or popliteal fossae, in stark contrast to the bites of many other medically relevant insects. Linear configurations are often observed.
The bites themselves are treated in the same way that most arthropod bites are treated: symptomatic relief with potent topical steroids such as betamethasone dipropionate and antihistamines such as hydroxyzine.
Regarding the potential for bed bugs to act as a vector for transmitting disease, the official position of the US Centers for Disease Control and Prevention (CDC), and the vast bulk of authorities for that matter, is that there is no evidence of successful transmission of any blood-borne pathogen via the bite of the bed bug. Therefore, additional laboratory testing, beyond bacterial culture of superinfected bite sites, is not, at present, justified. Despite this, however, it is frequently worried that the bite of bed bugs might transmit blood-borne pathogens, such as a hepatitis, HIV, or American trypanosomiasis.
It is widely asserted that one contributor to the recent ‘epidemic’ of bed bugs is travel. Indeed, many hotels and other shared lodging facilities, regardless of cleanliness or economic standing, may be infested with bed bugs and it is possible to bring an infestation home simply from staying in infested lodgings.
Treatment of Skin Disease Comprehensive Therapeutic Strategies 4e
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