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Severe Reaction from Envenomation by the Brown Widow Spider, Latrodectus geometricus (Araneae: Theridiidae)
Abstract
The brown widow, Latrodectus geometricus, is one of five species of Latrodectus in the United States, and is reported to be one of the least dangerous. However, we report a previously healthy patient bitten by a brown widow, resulting in a serious reaction requiring hospitalization. Symptoms included severe pain, cramps, nausea/vomiting, and fasciculations in the pectoral and quadriceps muscles. This report signals a need to re-evaluate previously held ideas that brown widow bites are of minor consequence.
... It also exhibits thanatosis, a behaviour characterized by jumping from its web, retracting its legs and playing dead when its protective retreat is disturbed (Vetter, 2008). Being the renowned relative of the notorious American black widow, Lactrodectus mactans, the brown widow bite envenomation effect is generally considered mild but it may potentially lead to severe envenomation similar to black widow bites, including severe pain, cramps, nausea and vomiting (Goddard et al., 2008). Despite its broad distribution worldwide, incidents of L. geometricus bite are poorly documented, and to date, medical literature of L. geometricus envenoming in Malaysia is non-existent. ...
... L. geometricus is considered to be non-aggressive because when threatened, they will withdraw from their webs and exhibit prolonged thanatosis (Mullen & Durden, 2002;Goddard et al., 2008). However, lactrodectism due to L. geometricus, some with severe reactions, have been reported (Cardoso et al., 2003;Goddard et al., 2008;Almeida et al., 2009;Earwood et al., 2020). ...
... L. geometricus is considered to be non-aggressive because when threatened, they will withdraw from their webs and exhibit prolonged thanatosis (Mullen & Durden, 2002;Goddard et al., 2008). However, lactrodectism due to L. geometricus, some with severe reactions, have been reported (Cardoso et al., 2003;Goddard et al., 2008;Almeida et al., 2009;Earwood et al., 2020). Despite the low average yield of venom produced by L. geometricus when compared against the other five Lactrodectus spp. ...
We report two confirmed human bite cases by Lactrodectus geometricus , also known as the brown widow spider. These are the first reported bite envenomation incidents by L. geometricus in Malaysia. The incidents occurred in Tawau, Sabah and Paka, Terengganu. Both men were bitten on their ear while putting on motorcycle helmets. The spiders appeared to have nested in the helmets. The dead specimens were collected and sent to the Invertebrate and Vertebrate Neurobiology Laboratory, Department of Parasitology, Universiti Malaya for identification. The species identity was confirmed by DNA barcoding.
... Envenomations by this species are rare. [4][5][6][7]10 Male widow spiders are smaller, lighter, and rarely inflict medically significant bites. [4][5][6] Black widow spiders are most active in the warmer months, tend to avoid occupied buildings, and are usually not aggressive, biting only when disturbed in their habitats of outbuildings, garages, and wood piles. ...
... [4][5][6] Black widow spiders are most active in the warmer months, tend to avoid occupied buildings, and are usually not aggressive, biting only when disturbed in their habitats of outbuildings, garages, and wood piles. [4][5][6][7] They are common in the Southern US. [4][5][6][7]10 When disturbed and torn, Latrodectus webs make an unmistakable crinkling sound that is usually different from other spider webs and may serve as a warning to individuals familiar with widow spider webs. 11 ...
... [4][5][6] Black widow spiders are most active in the warmer months, tend to avoid occupied buildings, and are usually not aggressive, biting only when disturbed in their habitats of outbuildings, garages, and wood piles. [4][5][6][7] They are common in the Southern US. [4][5][6][7]10 When disturbed and torn, Latrodectus webs make an unmistakable crinkling sound that is usually different from other spider webs and may serve as a warning to individuals familiar with widow spider webs. 11 ...
Unrecognized and untreated black widow spider bites cause significant pain, impairment, and rarely death. The widow venom, a powerful neurotoxin known as a-latrotoxin, causes muscle pain, diaphoresis, tachycardia, flushing, and hypertension. Treatment is usually symptomatic with a combination of opioid analgesics and muscle relaxants. If symptom resolution fails, an equine IgG antiserum is available, but a high index of clinical suspicion coupled with a knowledgeable patient history often allows successful treatment, especially when the treating physician possesses awareness of this type of bite and its usual course and possible complications.
... Further, the legs of the brown widow often have banding, unlike the solid colored legs of the black widow ( Figure 1). Female brown widows are not aggressive and will usually retreat unless forced against the skin [7]. Brown widows are seldom found in homes but rather living in clutter surrounding homes such as garages, woodpiles, and gardening equipment [8]. ...
... Clinical manifestations of latrodectism include local or generalized pain, abdominal pain, diaphoresis, nausea, vomiting and autonomic effects [8]. Indeed, there have been reports of brown widow bites resulting in moderate (as seen in our patient) to severe presentations of latrodectism [7,12,13]. These rare reactions appear closer to envenomation by black widows and include severe pain, nausea, vomiting, hypertension, and fasciculations. ...
Latrodectus geometricus, also known as the brown widow or brown button spider, is an unrenowned relative of the American black widow. While brown widow envenomation is generally thought of as mild, it does have the potential to lead to moderate or severe features similar to black widow bites. We report a case of brown widow envenomation that led to a moderate reaction including rash, local pain, pain radiating proximally in the extremity and nausea. Poison control was consulted for aid in spider identification. The patient was treated for pain control and muscle relaxation and monitored for eight hours. After proper tetanus prophylaxis, the patient was successfully discharged home with well-controlled, but continued mild symptoms. This case highlights a little-known, but clinically relevant species of widow spider with a wide distribution. Expeditious identification and treatment of brown widow bites can increase patient comfort, satisfaction, and discharge rates.
... To date, there have been no human deaths resulting from envenoming by S. nobilis or L. geometricus. While most bites result in mild symptoms, envenomings from both species have resulted in hospitalisations for symptoms such as debilitating pain, nausea, vomiting, cramps or vectored bacterial infection in the case of some S. nobilis envenomings (Almeida et al. 2009;Dunbar et al. 2018a;Dunbar et al. 2022b;Earwood et al. 2020;Goddard et al. 2008). On the other hand, envenoming by Latrodectus hesperus can lead to severe systemic symptoms (Clark et al. 1992;Nelsen et al. 2014). ...
The widow spiders of the genus Latrodectus (Araneae: Theridiidae) have a well-documented global medical significance due to the potent venom many of them possess. This medical importance partially stems from the global range expansion the genus has undergone, facilitated in part by human trade. This expansion has had an impact on human health in countries where Latrodectus spiders establish populations. Ireland has a detailed report history of accidental widow spider introductions, spanning over 30 years, which assists in understanding the potential such species have for establishing. Here we present three additional cases: a second and third record of Latrodectus geometricus (C.L. Koch, 1841) and the first record of Latrodectus hesperus (Chamberlin and Ivie, 1935). We also review all published reports of Latrodectus introductions in Ireland and discuss the potential for populations to establish. While case histories suggest that L. hesperus and L. geometricus can survive Irish winters, it is not certain that they can complete an egg-to-egg life cycle or even reproduce. Nevertheless, it seems possible they could do so in favourable micro-habitats in anthropogenic habitats such as hot houses. Identification of instances of Latrodectus introductions into Ireland is essential to prevent potential establishments that could lead to envenoming cases.
... However, some black widow bites might produce more significant systemic symptoms. The more severe, systemic signs that black widows are renowned for do occur in certain cases [26][27][28][29][30][31][32][33][34][35][36]. ...
Brown Widow Spider (Latrodectus geometricus) is recorded for the first time in Hail Region of Saudi Arabia .Three specimens of brown widow spider (L. geometricus) were found and collected on October, 2021 from inside a beehive in Al Hait city (Southern of Ha'il region of Saudi Arabia). The specimens were collected and submitted to Biology department of Hail University for the identification of morphological characters and DNA barcode sequence analysis of the specimen. Phylogenetic analysis was performed to compare the DNA sequence of the newly discovered female brown widow spider with the other species of Latrodectus genus.
... It can be found in agricultural areas, garages, and even houses. There is no surprise that cases of L. geometricus spider envenomation have been reported [7][8][9]. Therefore, Latrodectus is considered one of the most dangerous spider genera to humans and animals. ...
The brown widow spider, Latrodectus geometricus, is a predator of a variety of agricultural insects and is also hazardous for humans. Its venom is a true pharmacopeia representing neurotoxic peptides targeting the ion channels and/or receptors of both vertebrates and invertebrates. The lack of transcriptomic information, however, limits our knowledge of the diversity of components present in its venom. The purpose of this study was two-fold: (1) carry out a transcriptomic analysis of the venom, and (2) investigate the bioactivity of the venom using an electrophysiological bioassay. From 32,505 assembled transcripts, 8 toxin families were classified, and the ankyrin repeats (ANK), agatoxin, centipede toxin, ctenitoxin, lycotoxin, scorpion toxin-like, and SCP families were reported in the L. geometricus venom gland. The diversity of L. geometricus venom was also uncovered by the transcriptomics approach with the presence of defensins, chitinases, translationally controlled tumor proteins (TCTPs), leucine-rich proteins, serine proteases, and other important venom components. The venom was also chromatographically purified, and the activity contained in the fractions was investigated using an electrophysiological bioassay with the use of a voltage clamp on ion channels in order to find if the neurotoxic effects of the spider venom could be linked to a particular molecular target. The findings show that U24-ctenitoxin-Pn1a involves the inhibition of the insect sodium (Nav) channels, BgNav and DmNav. This study provides an overview of the molecular diversity of L. geometricus venom, which can be used as a reference for the venom of other spider species. The venom composition profile also increases our knowledge for the development of novel insecticides targeting voltage-gated sodium channels.
... These symptoms were alleviated after 6 h, and the patient recovered over the following 24 h. In addition to previously reported local symptoms, local burning was also reported during brown widow spider envenomation (Almeida et al., 2009;Goddard et al., 2008;Shackelford et al., 2015). ...
Spiders use their venom for defence and to capture prey. These venoms contain a cocktail of biologically active compounds that display several different biological activities, such as large molecules and small molecules including peptides, proteins/enzymes, and other components. Thus, venom constituents have attracted the attention of biochemists and pharmacologists over the years. The brown widow spider (Latrodectus geometricus) is a venomous spider found worldwide, including in Thailand. This spider causes human injuries, and the venom has many potential applications. In this study, we investigated the complexity and pharmacology of brown widow spider venom. Spider crude venom was investigated using partial proteome techniques and enzymatic activity, toxicity, and antibacterial activity assessments. We found that crude venom displayed a wide range of molecular masses from 19 to over 97 kDa, with molecular masses of 66 kDa intensely stained. Peptides and proteins were identified by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS), which showed that the crude venom contained a variety of substances, including latrotoxins, apolipophorins, hemocyanins, chitinases, arginine kinase, allergen antigen 5-like protein, astacin-like metalloproteases, and serine proteases. High hyaluronidase activity was observed based on the turbidimetric method. The venom presented toxicity in crickets (PD50 = 0.73 ± 0.10 μg/g body weight), and substantial envenomation symptoms, such as slow-motion movement, paralysis, and even death, were noted. Moreover, this venom exhibited potential antibacterial activity against the gram-positive Bacillus subtilis but not the gram-negative Pseudomonas aeruginosa. Spider venom contains numerous molecules with biological activity, such as latrotoxins, which affect insects, and enzymes. In addition to latrotoxins, certain enzymes in venom are hypothesized to exhibit toxicity and antimicrobial activity. This study provides important information for the further development of natural compounds or insecticidal toxins.
... For instance, in America they constitute a true medical emergency contributing to the rapid evolution of aracnoidism syndrome. L. geometricus VGH contains neurotoxins that cause alterations on striated muscle, causing several symptoms including paralysis, especially thoracic paralysis (Müller, 1993;Kiriakos et al., 2008;Goddard et al., 2008;Reyes-Lugo et al., 2009). ...
Brown widow spider (BrWS) (Latrodectus geometricus) venom produces intense systemic reactions such as cramps, harsh muscle nociceptive, nauseas, vomiting and hypertension. The proposed pathogenic mechanisms resulting in these accidents have principally been damages occurring at the nervous system. However, it is suspected that there is also damage of the adrenal glands, as a result of the experimental animal's clinical manifestations, which developed symptoms compatible with acute adrenal insufficiency. We have currently found that the adrenal gland is damaged by this venom gland homogenates (VGH) producing severe alterations on cortex cells resulting in death by acute adrenal insufficiency. In general, the ultrastructural study on the glands of mice under transmission electronic microscopy observations showed alterations in the majority of the intracellular membranes within 3 to 24 h. BrWSVGH also showed specific actions on extracellular matrix proteins such as fibronectin, laminin and fibrinogen. In addition, zymogram experiments using gelatin as substrates detected gelatinolytic activity. The molecular exclusion fractionation of crude BrWSVGH resulted in 15 fractions, of which F1 and F2 presented α/β-fibrinogenase and fibronectinolytic activities. Fractions F6, F14 and F15 showed only α-fibrinogenase activity; in contrast, the gelatinolytic action was only observed in fraction F11. Only metalloproteinase inhibitors abolished all these proteolytic activities. Our results suggest that adrenal cortex lesions may be relevant in the etiopathogenesis of severe brown widow spider envenoming. To our knowledge, this is the first report on adrenal gland damages, fibrinogenolytic activity and interrelations with cell-matrix adhesion proteins caused by L. geometricus VGH. The venom of this spider could be inducing hemostatic system damages on envenomed patients.
... The work of Mü ller (1993), which reports 15 veriÞed brown widow bites in Africa, shows that they pale in comparison to typical Latrodectus bites. Reports do exist of more substantial brown widow envenomations in Mississippi (Goddard et al. 2008), Brazil (Cardoso et al. 2003), and Venezuela (Kiriakos et al. 2008) but, as is typical in the medical literature, single case histories get published because of their extreme symptom expression and, hence, skew literature representation toward the rare and dynamic end of the spectrum. Although brown widows are now abundant in southern California, bites are not common where in our collective experience, we are only aware of one veriÞed brown widow bite, which had minor symptoms. ...
The brown widow spider, Latrodectus geometricus C. L. Koch, has become newly established in southern California during the first decade of the 21st century. Brown widows and egg sacs were collected within the urban Los Angeles Basin using timed searches. We also collected and compared the abundance and distribution of the native western black widow spider, Latrodectus hesperus Chamberlin & Ivie, to brown widows. Brown widows were very common around urban structures especially outside homes, in parks, under playground equipment, in plant nurseries and landscaping areas, greatly outnumbering native western black widows, and were very rare or nonexistent in garages, agricultural crops, and natural areas. Western black widows predominated in xeric habitats and were less prevalent around homes. Neither species was found in the living space of homes. In southern California, envenomation risk exists because brown widows are now common in urban areas and the spiders hide where people place their fingers and exert pressure to move objects (e.g., under the curled lip of potted plants, in the recessed handle of plastic trash bins). Nonetheless, brown widow spider bites are less toxic than those of native western black widow spiders and, hence, if they are displacing black widows, overall widow envenomation risk may actually be lower than before brown widow establishment.
... For instance, in America they constitute a true medical emergency contributing to the rapid evolution of aracnoidism syndrome. L. geometricus VGH contains neurotoxins that cause alterations on striated muscle, causing several symptoms including paralysis, especially thoracic paralysis (Müller, 1993; Kiriakos et al., 2008; Goddard et al., 2008; Reyes-Lugo et al., 2009). A comprehensive examination of the venomous proteins from spiders is not easily obtainable since it is very difficult to get enough quantities of spider venoms by extraction (even the milked venom may contain regurgitated material). ...
Brown widow spider (BrWS) (Latrodectus geometricus) venom produces intense systemic reactions such as cramps, harsh muscle nociceptive, nauseas, vomiting and hypertension. The proposed pathogenic mechanisms resulting in these accidents have principally been damages occurring at the nervous system. However, it is suspected that there is also damage of the adrenal glands, as a result of the experimental animal's clinical manifestations, which developed symptoms compatible with acute adrenal insufficiency. We have currently found that the adrenal gland is damaged by this venom gland homogenates (VGH) producing severe alterations on cortex cells resulting in death by acute adrenal insufficiency. In general, the ultrastructural study on the glands of mice under transmission electronic microscopy observations showed alterations in the majority of the intracellular membranes within 3 to 24h. BrWSVGH also showed specific actions on extracellular matrix proteins such as fibronectin, laminin and fibrinogen. In addition, zymogram experiments using gelatin as substrates detected gelatinolytic activity. The molecular exclusion fractionation of crude BrWSVGH resulted in 15 fractions, of which F1 and F2 presented alpha/beta-fibrinogenase and fibronectinolytic activities. Fractions F6, F14 and F15 showed only alpha-fibrinogenase activity; in contrast, the gelatinolytic action was only observed in fraction F11. Only metalloproteinase inhibitors abolished all these proteolytic activities. Our results suggest that adrenal cortex lesions may be relevant in the etiopathogenesis of severe brown widow spider envenoming. To our knowledge, this is the first report on adrenal gland damages, fibrinogenolytic activity and interrelations with cell-matrix adhesion proteins caused by L.geometricus VGH. The venom of this spider could be inducing hemostatic system damages on envenomed patients.
This study reports two cases of araneism in dogs caused by the bite of the brown widow spider (Latrodectus geometricus), one of which resulted in death. The first case presented mild signs, successfully treated with medication and ice packs. The second case, more severe, involved exacerbated local signs such as extensive edema and ecchymosis, and diffuse cutaneous hemorrhage in the affected limb, as well as systemic signs, including vomiting, tetraparesis, ataxia, and epileptic seizure, culminating in renal and hepatic failure, circulatory collapse, and death. The treatments employed were based on the symptoms and included the use of analgesics and anti-inflammatories. The study highlights the importance of early diagnosis and appropriate treatment, including the use of specific antivenoms in more severe cases. It emphasizes the importance of preventive measures, such as the use of insecticides, to prevent future accidents. Awareness of the clinical signs of poisoning and the available treatment options is crucial for healthcare professionals and veterinarians to ensure proper management of these incidents and minimize their consequences.
The brown widow spider, Latrodectus geometricus, is a hazardous and highly invasive species globally. One of the suggested mechanisms enhancing this spider’s invasiveness is lower susceptibility to natural enemies compared to other widow species. The parasitoid wasp, Philolema latrodecti, is known to attack egg sacs of L. geometricus, as well as those of other species of Latrodectus. Despite its potential importance as a natural enemy of L. geometricus, little is known about the development of this wasp and factors mediating its parasitism success. We investigated the development of this parasitoid in two widow spider host species, one native to Israel, the white widow, L. pallidus, and the invasive brown widow, L. geometricus. We compared wasp developmental success in egg sacs exposed to increasing wasp densities. We found increased wasp emergence and brood size, and smaller emerging wasp body size with increasing wasp density. Across all wasp densities, more and larger parasitoids developed in the egg sacs of the native host species, L. pallidus, compared to the invasive host species, L. geometricus. Parasitoid sex ratio was highly female-biased and the proportion of males increased with wasp density, suggesting local mate competition. Overall, our results suggest that L. pallidus is a better host for the egg sac parasitoid P. latrodecti, which could give a competitive advantage to the less-affected invasive brown widow spider.
Widow spiders belong to the cosmopolitan genus Latrodectus (Araneae: Theridiidae), of which five species are found in North America. In part due to their medical importance and common occurrence, they are ever-more popular study organisms in a wide variety of fields. However, the literature is widely dispersed, and a broad synthesis has not been attempted since 1970. Here, we review and synthesize published information on the five North American Latrodectus species: L. hesperus, L. mactans, L. variolus, L. bishopi, and the introduced L. geometricus. We focus on distribution, ecology, anatomy, physiology, reproduction, ontogeny, behaviour, web structure, silk, venom, genetics, and phylogeny. We also include some of our own observations on L. hesperus. We conclude by highlighting areas where further research would be especially fruitful.
Latrodectus geometricus (Araneae: Theridiidae), es una araña llamada vulgarmente “viuda marrón”. Originaria de África, es una especie sinantrópica y cosmopolita, muy frecuente en varias ciudades del centro y norte de Argentina. A diferencia de otras especies del género no suele causar envenenamientos graves, habiéndose registrado en el mundo muy pocos casos que requirieron tratamiento los cuales evolucionaron siempre de forma favorable. Todos los casos registrados hasta la fecha fueron atribuidos a hembras, asumiendo que los machos no causan casos clínicos e incluso serían incapaces de atravesar con sus quelíceros la piel humana debido a su pequeño tamaño. Este trabajo presenta el primer registro de un accidente causado por un macho de L. geometricus describiendo los síntomas. El accidente ocurrió a una mujer de 21 años en Villa Gobernador Gálvez (33°01'31" S, 60°38'01" O), Santa Fe, Argentina, en marzo 2016. El ejemplar murió en el momento siendo conservado y luego identificado según su genitalia como un macho adulto de L. geometricus. Los síntomas se relevaron desde el accidente hasta el cese de las manifestaciones sin intervención terapútica. En el momento la joven advirtió una sensación punzante seguida inmediatamente de ardor y eritema. Luego de 10 minutos el ardor aumentó, disminuyendo a los 20 minutos. Luego de una hora el ardor y el eritema disminuyeron considerablemente. Los resultados observados respaldan que L. geometricus no reviste peligrosidad en Argentina y evidencian que los quelíceros de los machos pueden atravesar la piel humana, al menos en zonas de piel delgada.
We describe urban spider faun in Ciudad Victoria, Tamaulipas, Mexico and it's distribution on the urban area. Cluster sampling was performed in three steps and 59 species were identified corresponding to 29 families. Two new records for the state were found, and the values for species richness, diversity and evenness, also level of synanthropy associated with the species are presented. Similarity was analyzed from five areas of the city.
This study provides the first accurate records of Latrodectus geometricus C. L. Koch, 1841 for Uruguay and extends the known distribution of this species to the Southeastern region of South America. Data and figures of the genitalic morphology for the recognition of the species and natural history in this country are indicated. In Uruguay L. geometricus was mainly restricted to urban areas at the west of this country and it is associated with locations with high human activity.
This paper presents two newly established species for French Polynesia: the invasive brown widow spider, Latrodectus geometricus C. L. Koch, and its potential biocontrol agent, the parasitoid wasp, Philolema latrodecti (Fullaway). The brown widow spider was recorded from the island of Moorea in 2006 and, since that discovery, the occurrence of this species has expanded to two of the five archipelagos of French Polynesia including the main island of Tahiti and four of the Cook Islands. Although the tropical climate contributes to the establishment of L. geometricus, a biotic factor, P. latrodecti, may restrain population from demographic explosion. This eurytomid wasp is present in French Polynesia and is a parasitoid that has been used in biological control of the southern black widow Latrodectus mactans (F.) in Hawaii. This wasp could become a significant limiting factor for L. geometricus distribution on these islands, as it was found in 31% of the Tahitian brown widow spider egg sacs that were dissected. However, thus far, the wasp was only found on Tahiti in association with the brown widow spider. Although the brown widow is generally considered to be less toxic than its black widow relatives, it remains of medical concern in French Polynesia because reactions to its bites can, at times, be severe. The spider remains of public concern because it is a novel species; it has the word widow in its name and dark morphs are mistaken as black widows.
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Background
The brown widow spider (Latrodectus geometricus Koch, 1841) has colonised many parts of the world from its continent of origin, Africa. By at least 1841, the species had successfully established populations in South America and has more recently expanded its range to the southern states of North America. This highly adaptable spider has been far more successful in finding its niche around the world than its famous cousins, the black widow, Latrodectus mactans, found in the south-eastern states of North America, and the red-back, Latrodectus hasselti, found mostly in Australia, New Zealand and Japan.
Methods
We performed an extensive web search of brown widow sightings and mapped the location of each sighting using ArcGIS. Specimens reputedly of the species L. geometricus were collected at three localities in Peninsular Malaysia. The spiders were identified and documented based on an examination of morphological characteristics and DNA barcoding.
Results
The spiders found in Peninsular Malaysia were confirmed to be Latrodectus geometricus based on their morphological characteristics and DNA barcodes. We recorded 354 sightings of the brown widow in 58 countries, including Peninsular Malaysia.
Conclusion
Reports from the Americas and the Far East suggest a global-wide invasion of the brown widow spider. Herein we report the arrival of the brown widow spider in Peninsular Malaysia and provide notes on the identification of the species and its recently expanded range.
Widow spiders (Latrodectus spp.), also known as "black widows", have a worldwide distribution and can cause latrodectism. To the best of our knowledge, in Brazil, only one case of Latrodectus geometricus (Koch, 1841) envenomation in a human has been reported. The aim of the present report is to describe a spider bite caused by Latrodectus geometricus in a patient who lives in Paranapanema, São Paulo state, Brazil.
In North America, spider envenomation is perceived to be a greater threat than in actuality; however, it still is a valid source of morbidity and, very rarely, mortality. Only 2 groups (widows, recluses) are medically important on this continent. Widow bites affect the neuromuscular junction, have minor dermatologic expression, and are treated with analgesics and antivenom. Recluse bites vary from mild, self-limiting rashes to extensive dermonecrosis. Recent awareness of methicillin-resistant Staphylococcus aureus as a ubiquitous cause of skin injury that is often mistaken as attributable to recluse bites has questioned the credence of spiders being the cause of idiopathic wounds.
The range of the brown widow spider Latrodectus geometricus C. L. Koch includes much of Africa and South and Central America. This medically important spider has been recently introduced to Japan, Indonesia, Papua New Guinea, Australia, Hawaii, and California. After the identification of the brown widow spider in New Orleans, LA, and southern Mississippi, surveys in the southeastern United States were conducted from the fall of 2006 through February 2008. We found populations of brown widow spiders in Georgia, Texas, and multiple localities in southeastern Louisiana and Mississippi. In Mississippi, specimens were collected as far north as a county bordering Tennessee. In New Orleans, the brown widow spider has been commonly collected from various locations where human contact is likely.
Cases of black widow (Latrodectus indistinctus) and brown widow (L. geometricus) spider bites referred to the Tygerberg Pharmacology and Toxicology Consultation Centre from the summer of 1987/88 to the summer of 1991/92 were entered into this series. Of a total of 45 patients, 30 had been bitten by black and 15 by brown widow spiders. It was evident that black widow spider bites caused a more severe form of envenomation than brown widow bites, characterised by generalised muscle pain and cramps, abdominal muscle rigidity, profuse sweating, raised blood pressure and tachycardia. The symptoms and signs of brown widow bites were mild and tended to be restricted to the bite site and surrounding tissues. Conditions which should be considered in the differential diagnosis include cytotoxic spider bite, scorpion sting, snakebite, acute abdominal conditions, myocardial infarction, alcohol withdrawal and organophosphate poisoning. To prevent the development of complications, the administration of black widow spider antivenom is recommended in severe cases because untreated latrodectism could become protracted, without improvement, for several days.
Four species of the black-widow spider genus Latrodectus are known to occur in North America. They are L. mactans mactans, L. geometricus, L. variolus and L. bishopi. Thecomparative lethality of the venoms of these species and of the European sub-species L. mactans tredecimguttatus was evaluated. All have very potent venoms although there are species differences in venom lethality and the average amount of venom obtained.
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Adult female brown widow spider
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Fig. Adult female brown widow spider. (Photo courtesy Dr.
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