Bed bugs seem tough but harmless, for now


Bed bugs seem tough but harmless, for now

A US study that reviewed the available evidence on bed bugs found that while they are highly resistant to various ways of getting rid of them, they seem to be more of a nuisance than a serious health problem, but the possibility that they could one day serve as a vehicle for disease has not been well researched.

The study was the work of Drs Jerome Goddard and Richard deShazo from the Department of Medicine, University of Mississippi Medical Center, Jackson, and is published online on 1 April in the Journal of the American Medical Association, JAMA. Goddard also works at the Department of Entomology and Plant Pathology, Mississippi State University.

The bed bug (Cimex lectularius) has been a human parasite for thousands of years, and infestations are rising fast, more so in developed countries, probably due to international travel, immigration, changes in how pests are controlled and insecticide resistance, wrote the authors.

Bed bugs prefer to hide within a few feet of their hosts, in places like mattress seams, crevices in the bed, behind the headboard and loose wallpaper.

From what we know, bed bug bites tend to be more of a nuisance than anything, although they can cause some skin reactions. However, their potential to serve as "disease vectors" and how best to control and eradicate them is not well understood.

For the study, Goddard and deShazo searched databases for medical and pest control articles from 1960 to 2008. They also did manual searches for older texts in journals, textbooks, trade journals and newspapers. This covered the period 1892 to 2008.

In their review they only included articles that met certain criteria in terms of clinical evidence for the medical articles and measured reductions of infestations for the pest control articles.

For instance, for the clinical studies, they included only original accounts of bed bug investigations that had enough detail of cause and effect between the insect bites and clinical effects and enough evidence that bed bugs were the source of the bites. On the pest control side, they only included articles that showed evidence that eradication led to a measured reduction in bed bugs.

They found 53 articles that met these criteria and included them in their summary review. They only found 2 clinical trials on bed bugs that " tested the ability of pest control interventions to eradicate bed bugs".

They found that a variety of clinical reactions to bed bugs have been reported, mostly skin reactions and rarely systemic reactions.

Also, although bed bugs have been blamed for transmitting over 40 human diseases, they found little evidence that "they are vectors of communicable diseases".

They also found that several kinds of treatment have been used for bed bug bites, with varying results. These include: antibiotics, antihistamines, corticosteroids (as creams and tablets), and epinephrine (adrenaline).

The researchers found no reports of evidence-based attempts to eradicate bed bugs or prevent bites.

They concluded that:

"Treatment options for cutaneous and systemic reactions from bed bug bites have not been evaluated in clinical trials and there is no evidence that outcomes differ significantly from those receiving no treatment."

"Evidence for disease transmission by bed bugs is lacking. Pest control and eradication is challenging due to insecticide resistance, lack of effective products, and health concerns about spraying mattresses with pesticides," they added.

Goddard and deShazo also wrote that bed bugs are very difficult to get rid of, and they are likely to become more of a problem as time goes on:

"Development of effective repellents and public education about bed bugs are also important goals. Research is needed to elucidate the pathogenesis of clinical reactions to bed bug bites so that optimal therapy may be identified," they added.

"Bed Bugs (Cimex lectularius) and Clinical Consequences of Their Bites."

Jerome Goddard; Richard deShazo.

JAMA, 2009;301(13):1358- 1366.

Vol. 301 No. 13, published online April 1, 2009

Sources: JAMA.

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Section Issues On Medicine: Disease