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How dangerous is the bite of a recluse spider? a.k.a. "brown recluse spider" by Jerry Cates
All recluse spiders (members of the family Loxoscelidae, which has but one genus, Loxosceles, roughly meaning "equal legs") are considered by many authorities to pose a danger to human health, as their venom is reputed to produce, in susceptible individuals, severe cases of tissue necrosis. In others the effect of recluse spider bites is mild or of no consequence. It is often said that most cases of recluse spider envenomation, where the spider could be identified, involve the brown recluse (Loxosceles reclusa). That species is said to possess a particularly potent venom, while those of other species, save perhaps L. laeta and L. intermedia, are considered less dangerous. Anywhere from six (Kaston) to thirteen (Breene) species of recluse spiders are commonly found in the contiguous 48 United States. One additional species, L. laeta, a recognized but infrequent import from South America, is sometimes found here as well. Much of the common literature on recluse spiders incorrectly states that the presence of a violin- or fiddle-shaped marking on the spider's back is the best way to identify a recluse spider, Several species of recluse spiders have no such markings, and other, non-recluse spiders have markings that superficially resemble a violin- or fiddle-shaped mark. The most accurate means of identifying a brown recluse spider in the field is with a magnifying glass. Once the intact spider has been killed, either with a contact spray or by immersing the spider in alcohol, an examination of the spider's head will show, for a recluse spider, three pairs of equal-sized eyes. One pair of eyes faces forward, and one pair faces to each side. Recluse spiders are nocturnal hunters that do not normally roam about in the daytime. During the day they hide in cracks and crevices, and under rocks or any other object that will serve as temporary shelter. These spiders mature from hatchling to adult during their first year of life, and thereafter live as long as seven years (in a suitable environment). They tend to be abundant wherever they are found, and if one specimen is found inside a house it is usual to find well in excess of 100 more on further examination. Despite the bad reputation this spider has, few or none of the inhabitants of homes infested with such spiders ever report bites that result in serious medical complications. Conversely, physicians all over the United States diagnose "brown recluse spider bites" with regularity, even in locales where recluse spiders have never been found. ---------------------------------------------- Please contact us about your personal experiences, if you have been bitten by a brown recluse, black widow, or any other spider, including jumping spiders and garden spiders (the bites of which typically produce a transitory inflammation, but resolve within a few days without medical attention), whether recently or in the past thirty years, anywhere in the world. For example, the bite of a species of garden spider, the golden orb spider of Australia [Nephila edulis] typically is unremarkable, but on occasion produces medically significant secondary infections; the frequency and nature of bites experienced from that species of spider is also a part of this study. One object of this study is to collect data that might relate to a mysterious series of spider-related infections, involving a special pathogen, that took place in the United States and in Australia between 1977 and 2006. Although only fifteen such infections were reported to medical establishments, seven appear to be associated with spider bites. Some authorities suggest that the number of actual infections of this type that occurred in the U.S. and Australia during the past thirty years is much larger, but that they have been underreported. Underreporting of specific kinds of infections can occur, either because the persons infected chose not to seek medical assistance, or the medical establishments misdiagnosed the infections as being caused by other infectious agents. We are seeking to establish an estimate of the number of human spider bites that occur each year by these and similar spiders, whether the bite resulted in injury to the human or not. Next, we hope to establish the number of instances where the bite (1) became inflamed and/or infected, then resolved without medical intervention, or (2) infected, ulcerated, or led to a generalized sickness, and required medical intervention. ---------------------------------------------- Back to: Recluse Spiders *Texas Spiders Back to: Bugsinthenews |
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