I’ve been looking at the literature concerning other blood-sucking pests as it is rich with insights and information that have not yet been investigated in bed bugs—and perhaps will not be any time soon because the clever bed bug does not vector disease organisms. (I want to tell you what I’ve found but I want to understand it better first.)
So I came across this description of surveillance activities for the Chagas vector Triatoma infestans, where the presumptive blood test known as the Kastle-Meyer test was used successfully, and it makes me wonder why this isn’t used more to exclude fecal trace evidence by people trying to ascertain the presence, or continued presence, of bed bugs. Lou Sorkin has mentioned this test to us before and I know some people have used it, but it’s certainly not used or recommended widely.
The authors describe the Kastle-Meyer test as 100% sensitive to black or dark brown fecal spots as old as 4 years:
Overall, 100% of black or dark brown triatomine-like dejecta from three species of laboratory-reared or field-collected triatomine bugs, mosquitoes, and cimicid bedbugs tested positively by the phenolphthalin test, regardless of the age of feces. All feces from cockroaches, which can be easily confounded with those from triatomine bugs, and from other arthropods tested negative. Therefore, the test very likely will give positive results in dark brown or black fecal smears (having heme residues) from other hematophagous arthropods.
Gürtler, R. E.; Oneto, M. L.; Cecere, M. C.; Castañera, M. B.; Canale, D. M. (2001) A Simple Method to Identify Triatomine (Hemiptera: Reduviidae) Feces in Sensing Devices Used in Vector Surveillance Programs. Journal of Medical Entomology. 38(2). 147-152.
You can read about the Kastle-Meyer test and find the kits and procedures by googling presumptive blood test kit.
The authors simplified the protocol for their purposes:
Trials were carried out to simplify procedures for testing samples in the field. Square pieces (7 by 7 cm) of filter paper were folded twice, and one of the corners was pressed onto the fecal spot and then unfolded. The smeared portion of the filter paper was wetted successively with one drop of ethanol, the Kastle-Meyer reagent, and hydrogen peroxide. Whenever the dejecta gave a positive reaction, a fuchsia color appeared in a few seconds and the filter papers were discarded. When color development was slow or abnormal, or faded very quickly, the sample was regarded as suspicious.
Perhaps the best way to find bed bugs is with a pair of well-trained eyes, which is exactly what most people do not have. I now feel very strongly that this is what people must be taught, especially in our city given the prevailing business practices, how to inspect for bed bugs and how to evaluate evidence of infestation, so that they can rely on themselves. The cavalry ain’t coming.
These pages may be of related interest:
This sounds most interesting, but pradtical? I remember many years ago using UV light for detecting rodent urine. The company had a neat device with a flashlight and a UV lamp (of the type that didn’t hurt the eyes and I went off looking for urine trails ……. A few years later, I managed to get some very inexpensive units for all my staff….. a bit of modern technology, but in truth, we hardly ever used them because in most cases the evidence was obvious and to use it well, you needed a fairly dark area… These devices were great for tough cases and for investigation of potential containmination of food containers but not very practical for day to day pest control.
I am thinking that perhaps this test could be useful in special cases which may involve litigation, but i think most pco’s look for patterns of fecal spotting, and it also comes down to where the spotting is found… kitchen.. it must be roaches about 99.9% of the time and for bedrooms, probably bed bugs if it is on beds though to be honest, I have seen roach nymphs in the folds of sofas and their fecal spotting could easily have been mistaken for bed bugs were it not for evidence of cast skins that were definitely roach nymphs.
So i say, a useful tool, good to know.. but likely very limited use in the field.
that is my take on it… but i am noting the item and will likely get a kit for future use in special cases as noted.. good stuff Renee.. you sure do find useful material…
Sam
Yes, perhaps you’re right but actually, I meant people, regular people, not professionals. This is where an acquaintance with what it’s like to have bed bugs is useful. When an infestation is waning (or indeed when it is first being identified, but particularly when it’s ending), people are confronted with limited evidence; their bites, if they’re allergic in the first place, may be changing due to the normal course of bite reactions; the fecal traces they find may be suspect but the visual experience to discriminate probable bed bug fecal spots from other things is not a skill people in general have (and the authors of this article indicate even experienced vector surveillance workers may misinterpret the signs). This is the stage where people may be anxious and weary of the long process. They may decide to have more ‘just in case’ bed bug treatments because they cannot be certain that the infestation is over; they may continue on the path of throwing out yet more things; they may despair of ever solving their problem and contemplate yet more expensive solutions. Sometimes there is the fear that bed bugs have returned and yet there are limited signs and now these potential signs must be interpreted, and so come the questions, what is the size and appearance of fecal spots, etc. People just don’t know these things and why would they. I’m not sure it’s practical for every situation, and if the infestation is fully evident, there is no need, but I wonder if people can consider it in these situations so that they can determine what is going on by themselves. There is no great surplus of qualified bed bug inspectors, and even if there is access to inspectors, there is as ever the issue of cost. In NYC in particular it is not an easy thing to get a pest control company to simply inspect. But, of course, I’m just wondering and posting for the consideration of others.