Venomous Snake and Spider Bites in Pregnancy

Importance

Venomous snake and spider bites are relatively rare in the Unites States and even more so in the pregnant population. However, the impact of a venomous bite, also known as an envenomation, can be serious in a pregnant patient. Thus, providers in endemic and high-risk areas must be familiar with the management of envenomation in the pregnant population.

Objective

The purpose of this article is to review the current literature on the most common snake and spider envenomations in the United States, the effects of envenomation on maternal and fetal health, and the management of envenomation in pregnancy.

Evidence Acquisition

Original research articles, review articles, and guidelines on snake and spider envenomation were reviewed.

Results

Snake envenomation carries higher risks of maternal morbidity and fetal morbidity and mortality than spider envenomation. Although the data are limited, current literature suggests that both snake and spider antivenom can be used in the pregnant population without significant adverse outcomes. However, the risks of an adverse hypersensitivity reaction with antivenom administration should be weighed carefully with the benefits.

Conclusions and Relevance

The use of antivenom therapy in the symptomatic envenomated pregnant population is likely safe with the appropriate monitoring and follow-up. Knowledge of the indications for antivenom therapy and proper escalation of care are vital to optimizing maternal and fetal outcomes. More research is needed to determine the effects of both envenomation and antivenom therapy on the pregnant patient and their fetus.

Clinical aspects, diagnosis and management of Loxosceles spider envenomation: literature and case review

The genus Loxosceles comprises 140 species widely distributed around the world. These spiders are nocturnal, sedentary and remarkably nonaggressive, although they cause accidents in humans with wide degrees of severity, generating signs and symptoms that define the clinical condition known as loxoscelism. Its local signs and symptoms were first reported in 1872, and over the years, a large medical literature has been accumulated; unfortunately, it is not always trustworthy. Assessing the reliability of such information, we reviewed 120 case reports of loxoscelism published in 84 articles over the past 20 years. This search allowed us to gather information on the clinical aspects, diagnosis and treatment of loxoscelism, showing that the severity of these accidents has multiple degrees and that it is influenced by many factors. Thus, coupled with epidemiological and species occurrence information, this study can be a useful tool for the clinical practice of loxoscelism. It may support and provide a multidisciplinary view that should be taken into consideration when establishing the therapeutic approach in cases of Loxosceles envenomation.

Probable cutaneous loxoscelism with mild systemic symptoms: A case report from Spain

We present a case from Valencia, Spain, of a 25-year-old woman who presented with a painful erythematous skin lesion, initially diagnosed as cellulitis. The lesion was unresponsive to antibiotic treatments and progressed into a hemorrhagic blister with necrotic ulcer formation. Posterior collection of a spider from the patient's home and expert identification of the spider as Loxosceles rufescens was achieved, establishing the diagnosis of probable cutaneous loxoscelism. Symptomatic treatment, general wound care and ultimately surgery, resulted in complete recovery with minor residual scarring. This case illustrates some of the difficulties encountered in the diagnosis and treatment of loxoscelism and adds to the increasing reports of loxoscelism in the Mediterranean Basin.

"Spider bite" lesions are usually diagnosed as skin and soft-tissue infections

BACKGROUND

Many people seek medical attention for skin lesions and other conditions they attribute to spider bites. Prior experience suggests that many of these lesions have alternate causes, especially infections with community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA).

OBJECTIVES

This study determined the percentage of emergency department (ED) patients reporting a "spider bite" who received a clinical diagnosis of spider bite by their physician vs. other etiologies, and if the diagnoses correlated with demographic risk factors for developing CA-MRSA infections.

METHODS

ED patients who reported that their condition was caused by a "spider bite" were prospectively enrolled in an anonymous, voluntary survey regarding details of their illness and demographic information. Discharge diagnoses were also collected and categorized as: spider bite, bite from other animal (including unknown arthropod), infection, or other diagnosis.

RESULTS

There were 182 patients enrolled over 23 months. Seven patients (3.8%) were diagnosed with actual spider bites, 9 patients (4.9%) with bites from other animals, 156 patients (85.7%) with infections, and 6 patients (3.3%) were given other diagnoses. Four patients were given concurrent diagnoses in two categories, and 8 (4.4%) did not have the diagnosis recorded on the data collection instrument. No statistically significant associations were found between the patients' diagnostic categories and the demographic risk factors for CA-MRSA assessed.

CONCLUSION

ED patients reporting a "spider bite" were most frequently diagnosed with skin and soft-tissue infections. Clinically confirmed spider bites were rare, and were caused by black widow spiders when the species could be identified.

Loxoscelism and Negative Pressure Wound Therapy (Vacuum-Assisted Closure): A Clinical Case Series

Brown recluse spider (Loxosceles sp) bites continue to be a significant challenge to manage clinically. Sequelae from these lesions range from chronic necrotic ulcers that persist for months to an acute life-threatening course of sepsis. Negative pressure wound therapy using vacuum-assisted closure (VAC) has been described for use in both acute and chronic wounds. We present a novel application for the use of this therapy in a retrospective review of eight clinical cases treated with the VAC.

Diagnostic challenges of early Lyme disease: lessons from a community case series

Background

Lyme disease, the most common vector-borne infection in North America, is increasingly reported. When the characteristic rash, erythema migrans, is not recognized and treated, delayed manifestations of disseminated infection may occur. The accuracy of diagnosis and treatment of early Lyme disease in the community is unknown.

Methods

A retrospective, consecutive case series of 165 patients presenting for possible early Lyme disease between August 1, 2002 and August 1, 2007 to a community-based Lyme referral practice in Maryland. All patients had acute symptoms of less than or equal to 12 weeks duration. Patients were categorized according to the Centers for Disease Control and Prevention criteria and data were collected on presenting history, physical findings, laboratory serology, prior diagnoses and prior treatments.

Results

The majority (61%) of patients in this case series were diagnosed with early Lyme disease. Of those diagnosed with early Lyme disease, 13% did not present with erythema migrans; of those not presenting with a rash, 54% had been previously misdiagnosed. Among those with a rash, the diagnosis of erythema migrans was initially missed in 23% of patients whose rash was subsequently confirmed. Of all patients previously misdiagnosed, 41% had received initial antibiotics likely to be ineffective against Lyme disease.

Conclusion

For community physicians practicing in high-risk geographic areas, the diagnosis of Lyme disease remains a challenge. Failure to recognize erythema migrans or alternatively, viral-like presentations without a rash, can lead to missed or delayed diagnosis of Lyme disease, ineffective antibiotic treatment, and the potential for late manifestations.

Distribution of the brown recluse spider (Araneae: Sicariidae) in Georgia with comparison to poison center reports of envenomations

Georgia is on the southeastern margin of the native range of the brown recluse spider, Loxosceles reclusa Gertsch and Mulaik. The brown recluse is not a common Georgia spider and has limited distribution in the state. Using recent submissions, previously published records, and examination of museum specimens, we document the spider's presence in 31 (19.5%) of Georgia's 159 counties, with almost all being found in the northern portion. The spider was collected almost exclusively north of the Fall Line (a transition zone separating the Piedmont and the Coastal Plain geological provinces). Only two locations in the southern Coastal Plain province produced L. reclusa specimens; these southern finds are considered spiders that were transported outside their range. There were six finds of the non-native world tramp species, L. rufescens (Dufour), three south of the Fall Line. In conspicuous contrast, over a 5-yr period, a Georgia poison center database recorded 963 reports of brown recluse spider bites from 103 counties. These figures greatly outnumber the historic verifications of brown recluses in the state for both specimen quantity and county occurrence, indicating improbable spider involvement and the overdiagnosis of bites. In the southern half of the state, medical diagnoses of brown recluse spider bites have virtually zero probability of being correct. Bite diagnoses should be made with caution in north Georgia given the spider's spotty distribution with low frequency of occurrence.

Medical aspects of spider bites

Spiders have been incriminated as causes of human suffering for centuries, but few species worldwide cause medically significant envenomation. Widow spiders (Latrodectus spp.) occur worldwide and cause latrodectism, which is characterized by pain (local and generalized) associated with nonspecific systemic effects, diaphoresis, and less commonly other autonomic and neurological effects. Recluse spiders (Loxosceles spp.) are distributed mostly through the tropical and subtropical Western Hemisphere and can cause severe skin lesions and rarely systemic effects; most bites are unremarkable. Highly dangerous spiders in South America (armed spiders) and Australia (funnel-web spiders) cause rare but severe envenomation requiring medical intervention and sometimes antivenom. Most other spiders involved in verified bites cause minor, transient effects. Many spiders blamed for causing medical mischief have been elevated to medical significance via circumstantial evidence, poor reporting, and repetitive citation in the literature; several species have been shown to be harmless with more stringent scientific evidence involving verified bites in humans.

Biotechnological applications of brown spider (Loxosceles genus) venom toxins

Loxoscelism (the term used to define accidents by the bite of brown spiders) has been reported worldwide. Clinical manifestations following brown spider bites are frequently associated with skin degeneration, a massive inflammatory response at the injured region, intravascular hemolysis, platelet aggregation causing thrombocytopenia and renal disturbances. The mechanisms by which the venom exerts its noxious effects are currently under investigation. The whole venom is a complex mixture of toxins enriched with low molecular mass proteins in the range of 5-40 kDa. Toxins including alkaline phosphatase, hyaluronidase, metalloproteases (astacin-like proteases), low molecular mass (5.6-7.9 kDa) insecticidal peptides and phospholipases-D (dermonecrotic toxins) have been identified in the venom. The purpose of the present review is to describe biotechnological applications of whole venom or some toxins, with especial emphasis upon molecular biology findings obtained in the last years.

Envenomations

Numerous types of envenomations may be encountered by health care workers depending on where in North America they work. Clinicians should be familiar with the animals in their region that may lead to envenomation.A rational approach with use of poison center or medical toxicology consultation services ensures that cases are managed appropriately.

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.

Brown spiders and loxoscelism

Accidents caused by brown spiders (Loxosceles genus) are classically associated with dermonecrotic lesions and systemic manifestations including intravascular haemolysis, disseminated intravascular coagulation and acute renal failure. Systemic reactions occur in a minority of cases, but may be severe in some patients and occasionally fatal. The mechanisms by which Loxosceles venom exerts these noxious effects are currently under investigation. The venom contains several toxins, some of which have been well-characterised biochemically and biologically. The purpose of the present review is to describe some insights into loxoscelism obtained over the last ten years. The biology and epidemiology of the brown spider, the histopathology of envenomation and the immunogenicity of Loxosceles venom are reviewed, as are the clinical features, diagnosis and therapy of brown spider bites. The identification and characterisation of some toxins and the mechanism of induction of local and systemic lesions caused by brown spider venom are also discussed. Finally, the biotechnological application of some venom toxins are covered.

Loxoscelism: Old obstacles, new directions

Loxosceles spiders have a worldwide distribution and are considered one of the most medically important groups of spiders. Envenomation (loxoscelism) can result in dermonecrosis and, less commonly, a systemic illness that can be fatal. The mechanism of venom action is multifactorial and incompletely understood. The characteristic dermonecrotic lesion results from the direct effects of the venom on the cellular and basal membrane components, as well as the extracellular matrix. The initial interaction between the venom and tissues causes complement activation, migration of polymorphic neutrophils, liberation of proteolytic enzymes, cytokine and chemokine release, platelet aggregation, and blood flow alterations that result in edema and ischemia, with development of necrosis. There is no definitive treatment for loxoscelism. However, animal model studies suggest the potential value of specific antivenom to decrease lesion size and limit systemic illness even when such administration is delayed.

Clinical consequences of spider bites: recent advances in our understanding

Spider bite continues to be a controversial subject worldwide and attribution of clinical effects to different spiders is problematic because of poor case definition and paucity of clinical evidence. The effects of medically important spiders are sometimes underestimated and simultaneously there is misattribution of effects to harmless spider groups. The majority of suspected spider bites present as skin lesions or necrotic ulcers where the history of a spider bite must be confirmed. To be a definite spider bite, the patient must immediately observe the spider and there be evidence of the bite, such as pain. Important groups of spiders worldwide include the widow spiders (latrodectism), recluse spiders (loxoscelism) and some mygalomorph spiders including the Australian Funnel web spider. Most spiders only cause minor effects, including a large number of groups that have been implicated in necrotic arachnidism.

Arachnid envenomation

This article focuses on the medically relevant arachnid species found in North America and selected other arachnids from around the world. While it is largely still true that the geographic location of the envenomation assists in determining the species responsible, the booming trade in arachnids as exotic pets should prompt the clinician to inquire into this possibility. Expert advice should be sought in either case; species identification is critical in determining the need for and proper type of antivenom therapy.

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 spiders: a review to help guide physicians in nonendemic areas

The brown recluse spider (Loxosceles reclusa) exists in significant populations mainly in the midwestern United States. Although bites can cause significant harm, envenomation is infrequent, and cases are usually clinically insignificant. Proper knowledge of the spider's habitat and lifestyle as well as the signs and symptoms of loxoscelism are needed to assess clinical cases adequately. Loxoscelism can masquerade as many serious pathologies, and vice versa, so it is important for the clinician to explore all possibilities in the differential diagnosis thoroughly. Treatments are controversial, and no conclusive test for envenomation is currently available. This review provides information to help physicians, especially in nonendemic areas, include or exclude brown recluse bite in the clinical diagnosis and provide proper care.

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.

An infestation of 2,055 brown recluse spiders (Araneae: Sicariidae) and no envenomations in a Kansas home: implications for bite diagnoses in nonendemic areas

During a 6-mo period, 2,055 brown recluse spiders, Loxosceles reclusa Gertsch and Mulaik, were collected in a 19th-century-built, currently occupied home in Lenexa, KS. We conservatively estimate that at least 400 of these spiders were large enough to cause envenomation. Additional collections from more typically infested homes in Missouri and Oklahoma in 2001 yielded 45 and 30 brown recluse spiders, respectively. Despite these infestations, no envenomations of the inhabitants of these three homes occurred. Considering the levels of infestations with no bites in the homes presented here, nonendemic areas in the United States, which typically lack recluse spider populations and have had zero to few verified specimens of the spider, do not have sufficient numbers of brown recluse spiders to make envenomation a likely scenario. Despite this, physicians from nonendemic recluse areas often diagnose brown recluse bites which, therefore, are unlikely to be correct.