Bedbug Detection Squad
By Carol A. Kemper, MD, FACP, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center. Dr. Kemper does research for Abbott Laboratories and Merck. The article originally appeared in the May 2013 issue of Infectious Disease Alert.
Source: Vaidyanathan R, Feldlaufer MF. Bed bug detection: Current technologies and future directions. Am J Trop Med Hyg 2013;88:619-625.
Remember that scene in Doc Martin when he travels to London for a conference, and while his lady awaits his affection in a tiny negligee, he methodically strips the bed looking for bed bugs? How many of us make that a habit now when traveling?
Detection and control of bedbugs has become a busy industry the past decade, as estimates suggest 100-fold increase in the bed bug population. Bed bug bites vary from a few annoying bites to dramatic infestations, sometimes resulting in severe allergic reactions, delayed hypersensitivity reactions, and even anemia. I’ve seen patients come in with hundreds of bites, desperate for information and relief.
There are a number of methods and technologies to detect (and possibly control) bed bug infestations, including newer technologies pending patent. Visual inspection of beds and furniture for bugs, exuviae, and fecal droplets is cheap and easy — but you have to know what you’re looking for and accuracy drops off with lesser infestations. It is also time-consuming (having to remake all those beds). There are a number of passive methods used, most of which employee glue or adhesive “traps,” which vary in price from a few cents to $30 for a 12-pack. These are undoubtedly better than passive inspection, especially if you are staying in a place for more than one night. But the traps must be manually removed and inspected, and they often have a mix of live and dead bugs stuck to them — and the traps are not specific for bedbugs so can attract other insects (some people might object to this). Another passive method is a coaster trap for furniture and bed legs, which can be left for a week at a time, and reportedly trap 6-7 times the bed bugs of other passive traps. But they too need to be removed and inspected, and are also non-specific for bed bugs. They cost anywhere from $34 to $80 for a 12-pack.
Active traps can employ a number of methods, including heat and CO2, which are the two most effective attractants, bringing in bugs at night wanting to feed. Traps based on CO2 productions are, however, more costly, varying in price from $400 to $999, and require refillable CO2 cartridges. In addition to cost, these systems also require visual inspection and removal of traps with live bugs and their feces, and operators often complain about the bulky cartridges, mechanical problems with the dispersal systems, and the constant hissing sound of the CO2 being dispersed. One study found that a homemade passive trap using dry ice was more successful than more expensive commercial traps using CO2 — the homemade dry ice system caught as many bugs in one day as the more expensive traps caught in a week.
Newer active trap systems, based on an increased understanding of bed bug interactions and chemical communication, are being developed. Two “alarm” pheromones have been identified, specific to bed bugs, and have been incorporated into active traps. They can also be used in part as a control strategy, because they are more effective at attracting bugs. Bedbugs have also been found to use another pheromone to signal gregarious behavior (called a kairomone), which seems to promote aggregation behavior, thereby possibly allowing better control of infestations. Such systems are advertised for $30 for a 90-day supply.
Pest control companies have also used trained canines for bed bug detection. While it is not entirely clear what the dogs are smelling, they presumably are responding to some combination of volatile pheromones or chemicals in bug excrement. These authors found that a trained dog identified live bed bugs, filter paper with a mix of the two alarm pheromones, and cast skins 100% of the time, although they commented that this was in a clean, well appointed office building. Lower detection rates have been reported when dogs are used in crowded urban settings. One issue with the use of dogs is they may not be able to detect a current infestation from a past infestation, and the dogs can only detect the presence of bed bugs — not reduce their numbers. Newer technologies based on antigens from digested human blood in bed bug feces are also being explored — but again have the disadvantage of not being able to detect current from past infestations. Other technologies based on mass spectrometry, DNA analysis, and electronic noses are accurate but impractical for commercial home use.