Biomedical subjects
Richard S Vetter
Publications and source records attributed to Richard S Vetter.
Verified bites by the woodlouse spider, Dysdera crocata.
Bites by the woodlouse spider, Dysdera crocata, are virtually innocuous. The main symptom is minor pain, typically lasting less than 1h, probably due mostly to mechanical puncture of the skin. However, because the spider has a strong proclivity to bite, has large fangs which it bares when threatened and is commonly mistaken for the medically important brown recluse spider in the United States, documentation of the mild effects of its bites may prevent excessive, unwarranted and possibly harmful treatment. We present information on eight verified bites reported to us as well as eight additional bites recorded in the literature.
Temporal integrity of an airborne odor stimulus is greatly affected by physical aspects of the odor delivery system.
There is currently a debate about the role played by temporal patterns in neural activity in olfactory coding. An accurate analysis of this question, however, is only possible if the temporal properties of a stimulus itself are well defined. So far, no technique with sufficient temporal resolution has been available to accomplish this. Using a photoionization detector (PID), we show that the configuration of the odor delivery apparatus and the airflow settings greatly influence the integrity of a stimulus profile within an odor delivery apparatus. In a situation where pulsatile odor stimuli are applied to a stationary preparation, we tested the effect of 1) axial and off-center location within the airstream, 2) airflow of the odor delivery, 3) exit tube length, 4) exit tube diameter, 5) orientation of the odor delivery device in relation to the exhaust flow, and 6) exhaust tube air speed. This has important implications for the study of time in olfaction; significant planning must be incorporated into the design of the experiment to provide a well-defined odor delivery system.
Verified bites by yellow sac spiders (genus Cheiracanthium) in the United States and Australia: where is the necrosis?
Spiders of the genus Cheiracanthium are frequently reported in review articles and medical references to be a definitive cause of dermonecrosis or necrotic arachnidism in humans. We provide 20 cases of verified bites by Cheiracanthium spiders from the United States and Australia, none with necrosis. A review of the international literature on 39 verified Cheiracanthium bites found only one case of mild necrosis in the European species C. punctorium. The basis for the suggestion that this spider genus causes dermonecrosis seems to be mostly inference from venom experiments in rabbits and guinea pigs, circumstantial spider involvement in human skin lesions, and repetitive citation of non-definitive reports in the medical literature. We discuss factors that lead to the erroneous elevation of virtually innocuous spiders to that of significant medical concern, which is a recurring problem in the medical community.
Bites of brown recluse spiders and suspected necrotic arachnidism.
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Loxoscelism and necrotic arachnidism: more myths and minor corrections.
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Arthropods in dermatology: errors in arachnology.
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Arachnids submitted as suspected brown recluse spiders (Araneae: Sicariidae): Loxosceles spiders are virtually restricted to their known distributions but are perceived to exist throughout the United States.
An Internet offer was made to identify any spider in the United States perceived to be a brown recluse spider, Loxosceles reclusa Gertsch & Mulaik (Sicariidae). In total, 1,773 arachnids from 49 states represented three orders (Araneae, Solifugae, and Opiliones) and the identifiable spiders (Araneae) consisted of 38 families, 88 genera, and 158 recognizable species. Participants from states at least half within the known brown recluse distribution submitted Loxosceles spiders 32- 89% of the time, except Louisiana and Mississippi with no submissions. From 25 of 29 states completely or almost completely outside of the range of Loxosceles spiders, no recluse spiders were submitted. Only two discoveries of brown recluses and two of the worldwide tramp species Loxosceles rufescens (Dufour) were submitted from nonendemic Loxosceles areas. States on distribution margins of brown recluse or other native Loxosceles spiders were intermediate in their Loxosceles submissions. This study showed that 1) the general public perceives brown recluses to occur over wide-ranging areas of the United States; and 2) brown recluses are frequently submitted from endemic states and almost never from nonendemic states, and therefore are virtually limited to their known distributions. This study corroborates opinions that diagnosis of brown recluse spider bites is best restricted to areas historically supporting proven, widespread populations of Loxosceles spiders.
Spider bites: addressing mythology and poor evidence.
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Additional considerations in presumptive brown recluse spider bites and dapsone therapy.
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Do hobo spider bites cause dermonecrotic injuries?
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Reports of envenomation by brown recluse spiders (Araneae: Sicariidae) outnumber verifications of Loxosceles spiders in Florida.
Bites attributed to the brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, are frequently reported by medical personnel throughout Florida, whereas the extensive arachnological evidence contradicts the alleged widespread occurrence of Loxosceles spiders in the state. We compared reports of brown recluse spider bites made by medical personnel from a 6-yr Florida poison control center database to the known verifications of Loxosceles spiders from 100 yr of Florida arachnological data. Medical personnel diagnosed 124 brown recluse spider bites from 31 of Florida's 67 counties in 6 yr. In contrast, only 11 finds of approximately 70 Loxosceles spiders have been made in 10 Florida counties in 100 yr. Florida does not have sufficient widespread populations of Loxosceles spiders to warrant consideration of brown recluse spider envenomation as a probable etiology of dermonecrosis. Florida health care would improve if medical personnel would consider the multitude of other etiologies that manifest in dermonecrosis.
An approach to spider bites. Erroneous attribution of dermonecrotic lesions to brown recluse or hobo spider bites in Canada.
OBJECTIVE: To dispel prevalent myths surrounding diagnosis of dermonecrotic and associated conditions supposedly resulting from bites of brown recluse, hobo, or other spiders in Canada. SOURCES OF INFORMATION: Worldwide, spider bites are regularly misdiagnosed as the etiologic agents in human dermonecrosis mainly as a result of inaccurate, erroneous, or hyperbolic popular and professional literature based on inference, circumstantial evidence, inferior clinical trials, and misunderstanding of the facts regarding spider-bite envenomation. MAIN MESSAGE: A working diagnosis of "spider bite" or publishing a case history should be considered only when a spider is caught in the act of biting or otherwise reliably associated with a lesion. Accurate identification of the spider could be critical for correct diagnosis and subsequent treatment. CONCLUSION: Brown recluse spiders are not found in Canada. Hobo spiders have not been reliably implicated in dermonecrosis. Worldwide, spider-bite envenomation is an unlikely cause of dermonecrosis. Canadian physicians should give priority consideration to other, more likely, causes.
Diagnoses of brown recluse spider bites (loxoscelism) greatly outnumber actual verifications of the spider in four western American states.
We attempt to demonstrate that physicians overdiagnose loxoscelism (colloquially known as 'brown recluse spider bites') by comparing the numbers of such diagnoses to the historically known numbers of Loxosceles spiders from the same areas in four western American states. The medical community from non-endemic Loxosceles areas often makes loxoscelism diagnoses solely on the basis of dermonecrotic lesions where Loxosceles spiders are rare or non-existent. If these diagnoses were correct then Loxosceles populations should be evident, specimens should readily be collected over the years and there should be a reasonable correlation between diagnoses and spider specimens. In 41 months of data collection, we were informed of 216 loxoscelism diagnoses from California, Oregon, Washington and Colorado. In contrast, from these four states, we can only find historical evidence of 35 brown recluse or Mediterranean recluse spiders. There is no consistency between localities of known Loxosceles populations and loxoscelism diagnoses. There are many conditions of diverse etiology that manifest in dermonecrosis. In the western United States, physician familiarity with these conditions will lead to more accurate diagnoses and subsequent proper remedy.
Brown recluse spider bite diagnoses and lawsuits.
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Distribution of the medically-implicated hobo spider (Araneae: Agelenidae) and a benign congener, Tegenaria duellica, in the United States and Canada.
The hobo spider, Tegenaria agrestis (Walckenaer), and the related Tegenaria duellica Simon are very similar European spiders that have become well established in the northwestern United States and British Columbia. The hobo spider is considered to be medically important; T. duellica is considered harmless but is often misidentified as the hobo spider. The current distribution of the hobo spider includes southern British Columbia, Washington, Oregon, Idaho, northern Utah, the western half of Montana, western Wyoming, and two small, isolated populations in Colorado. T. duellica is found mostly west of the Cascade and Coastal mountain ranges from southern British Columbia to central Oregon. In large human population centers where both species are sympatric, T. duellica is usually more common than the hobo spider. Data from a total of 1,232 hobo spiders and 395 T. duellica are included in this study.
Reports of presumptive brown recluse spider bites reinforce improbable diagnosis in regions of North America where the spider is not endemic.
Envenomations by the brown recluse spider have been reported throughout North America, despite the fact that the spider's range is limited to the South and central Midwest of the United States. Several of these medical reports have originated from regions of nonendemicity where the spider has never or rarely been documented and brown recluse spider populations are unknown. In most of these reports, no spider is positively identified in association with the dermonecrotic wound, and diagnosis has been based on clinical examination findings. Considering the extreme rarity of brown recluse spiders in areas of nonendemicity, the diagnosis of a presumptive bite is a misdiagnosis that reinforces the assumption that brown recluse spiders are common local etiologic agents of necrosis. There are many medical conditions of diverse origin that have been misdiagnosed as brown recluse spider bites, some of which can be fatal or debilitating. Physicians' awareness of these conditions will increase diagnostic accuracy in areas of North America where bites from brown recluse spiders are improbable.
Chemical burn misdiagnosed as brown recluse spider bite.
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