Posted by Librarian on 3/19/2002, 10:08 am
Message modified by board administrator 10/2/2005, 9:56 am

In search for the haphazardly elusive: a follow-up report on an investigation into the possible role of collembolans in human dermatitis Fredric L. Frye, 741 Plum Lane Davis, California 95616-3237 USA Introduction This is a follow-up to my previous paper entitled "Collemboliasis: yet another emerging zoonosis? A preliminary report," which was published in the April, 1996b issue of Veterinary Invertebrate Society Newsletter, 9:2-7. During 1996 and early 1997 twenty supposed cases of human parasitism claimed to be associated with insects and other invertebrates, including but not limited to collembolans, were submitted initially to the National Pediculosis Association (NPA) and then submitted to me for microscopic identification and evaluation. Investigation of these patients and the objects that were recovered from them resulted in examination of over 1,000 individual specimens. In each instance, one or more physicians had diagnosed these patients as suffering from"delusional parasitosis." All of the patients --and the NPA -- thought that this diagnosis was incorrect, and perceived it as being highly pejorative. The vast majority of the patients were female. The only "infested" mate was the spouse of a male patient. One patient reported that her child was similarly infested but no specimens were submitted from the child. Using the Internet to disseminate various "theories," many of these patients proposed alternative aetiologies that could be responsible for their suffering to the NPA and me. Citing Rachel Carson’s Silent Spring, some of the "agents" suggested for their condition were: over-application of environmental pesticides and scabicides; over-application of topical antipediculosis medications; the ubiquitous Serratia marcescens, nematomorpha ("horsehair worms"); and "soil-dwelling" rotifers. The fact that most of these and many other proposed "causes" had been studied and then discarded due to the lack of credible evidence did not dissuade those with firmly held beliefs. I was approached by the NPA to serve pro bono as their consulting pathologist and parasitologist. I did not fully appreciate how time-consuming this service would prove to be, and I naively accepted that invitation as a new and interesting challenge for which I was well prepared; after all, veterinary students receive far more training in parasitology than do human medical students. This situation was rapidly getting out of control as I tried to inform and convince these patients that their perceived skin disorders could not be induced by non-parasitic organisms. Dealing with these patients requires patience, compassion, and sensitivity: Telephone calls in the middle of the night and on weekends were commonplace. As a variety of parasitic, non-parasitic, commensal, and/or otherwise innocuous organisms were being submitted to me from otherwise rational persons, it soon became evident that self-collection of specimens constituted an unreliable method for obtaining meaningful material for analysis. Materials and methods Initially, patients suffering from what they perceived to be integumentary signs and symptoms of pruritus, skin "tingling" or "pin-pricks" associated with arthropods, were encouraged by the NPA to submit specimens in small volumes of 40% ethyl alcohol (80-proof vodka).. These specimens included skin scrapings and dermal detritus that were obtained by the patients and, in only a very few instances, by their attending physicians. In addition, oral and nasal sputum and mucus, vaginal, and perianal specimens were self-collected and submitted directly to me. One patient was unalterably convinced that he had passed a small octopus from his anus; however, he was unable to collect and send it to me. Several reported seeing "worms" in their excrement but, again, none was able to produce them for identification. Upon receipt, each specimen was aspirated from the vodka, mounted in Hoyer’s medium, coverslipped, and warmed for varying lengths of time on a heated plate until the specimens were sufficiently cleared and any air bubbles were excluded. The mounted and cleared specimens were examined microscopically immediately with plain and cross-polarised illumination, and then at 12-, 24-, and 96- hour intervals. Significant objects were recorded photographically on colour film with an Olympus BHB photomicroscope. A formal written report was issued, with copies furnished to the NPA, the patients, and their referring or attending physicians. Figure 1. Some of the arthropods obtained from patients An ancillary investigation into the nature of felted wads of fibers was accomplished by selecting, mounting, clearing, photographing and comparing coloured and uncoloured (white) and natural cotton and wool cloth fibres frmm several garments. An identical protocol investigated artificial (Polafrfil) fibres.