Loxosceles rufescens is a spider that may bite humans. To describe the clinical manifestations and treatment of patients with bites caused by L. rufescens, and present scanning electron microscopy of the spider. Twelve patients are described, seven with a confirmed aetiological diagnosis as a sample of the spider was captured. In one case, scanning electron microscopy of the spider was performed. Seven patients presented with a single necrotic ulcer of varying morphology, with a purulent-necrotic bed, located on the neck (one patient), buttock (one patient), thigh (one patient), legs (three patients) and foot (one patient). All patients complained of burning and pain. No systemic symptoms were observed. All patients were treated with sodium hypochlorite solution packs, an equine catalase gel, and polyhexamethylene biguanide cream. Oral analgesics were added. In one patient, oral prednisone was prescribed. Two patients with bacterial superinfections were treated with i.v. piperacillin/tazobactam or i.m. ceftriaxone. All patients recovered within eight weeks, however, a scar developed in five of six patients. The sequence of cutaneous manifestations due to L. rufescens bites is typical. At first, erythema and oedema forms, followed by a vesicle, blister or pustule and, finally, an eschar and scar. Systemic symptoms and signs are rare. To consider this spider as an aetiological agent of necrotic ulcers, it is necessary to capture a sample of the spider, dead or alive, which should then be identified by an expert. Corticosteroids, antibiotics and analgesics are frequently used. Surgery is often necessary.

The brown recluse spider (Loxosceles reclusa) is endemic to the southcentral Midwest and the Southern United States. A bite from a brown recluse spider may result in symptoms that range from local skin necrosis to systemic complications such as acute haemolytic anaemia, disseminated intravascular coagulopathy, rhabdomyolysis and death. Although rare, systemic loxoscelism is a clinical diagnosis of exclusion that should be considered in a patient with acute autoimmune haemolytic anaemia. We describe a case of a young man with autoimmune haemolytic anaemia secondary to systemic loxoscelism successfully treated with intravenous immunoglobulin and steroids.

UNASSIGNED: The authors have no conflicts of interest.

Poecilotheria spiders are considered theraphosids of underestimated clinical importance, with bites from these species inducing symptoms such as severe pain and intense muscle cramps. However, there is no specific treatment for the envenomation caused by these species, which, while native to India and Sri Lanka, are widely distributed worldwide. The present study reports the case of a 31-year-old man bitten by a Poecilotheria regalis specimen. The patient\'s clinical presentation was similar to Latrodectus envenomation, and patient was treated with an L. mactans antivenom. Most of patient\'s symptoms improved (fasciculations, pain, erythema, and local swelling), except muscle cramps. A toxicological study conducted on mice did not show that L. mactans antivenom has a neutralizing effect on the toxicity of P. regalis. The present report discusses the envenoming process of Poecilotheria species and the possible neutralizing effect exerted by L. mactans antivenom.

Poisoning by widow-spider (genus Latrodectus) bites occurs worldwide. The illness, termed latrodectism, can cause severe and persistent pain and can lead to muscle rigidity, respiratory complications, and cardiac problems. It is a global health challenge especially in developing countries. Equine serum-derived polyclonal anti-sera are commercially available as a medication for patients with latrodectism, but the use of sera imposes potential inherent risks related to its animal origin. The treatment may cause allergic reactions in humans (serum sickness), including anaphylactic shock. Furthermore, equine-derived antivenom is observed to have batch-to-batch variability and poor specificity, as it is always an undefined mix of antibodies. Because latrodectism can be extremely painful but is rarely fatal, the use of antivenom is controversial and only a small fraction of patients is treated. In this work, recombinant human antibodies were selected against alpha-latrotoxin of the European black widow (Latrodectus tredecimguttatus) by phage display from a naïve antibody gene library. Alpha-Latrotoxin (α-LTX) binding scFv were recloned and produced as fully human IgG. A novel alamarBlue assay for venom neutralization was developed and used to select neutralizing IgGs. The human antibodies showed in vitro neutralization efficacy both as single antibodies and antibody combinations. This was also confirmed by electrophysiological measurements of neuronal activity in cell culture. The best neutralizing antibodies showed nanomolar affinities. Antibody MRU44-4-A1 showed outstanding neutralization efficacy and affinity to L. tredecimguttatus α-LTX. Interestingly, only two of the neutralizing antibodies showed cross-neutralization of the venom of the Southern black widow (Latrodectus mactans). This was unexpected, because in the current literature the alpha-latrotoxins are described as highly conserved. The here-engineered antibodies are candidates for future development as potential therapeutics and diagnostic tools, as they for the first time would provide unlimited supply of a chemically completely defined drug of constant quality and efficacy, which is also made without the use of animals.

Brown recluse spider bites can lead to severe reactions such as skin necrosis,hemolytic anemia, and multiorgan failure, which can be life-threatening. Therapeutic plasma exchange has been reported to provide clinical benefit for such cases. In thisreport, we present a case of a brown recluse spider bite that was successfully treated with therapeutic plasma exchange and compare it with previous case reports.

The impact of Covid-19 on envenomations by venomous animals in countries heavily affected by both conditions has not been quantified yet. Brazil shows high incidence of envenomations by scorpions, spiders and snakes and was heavily affected by waves of Covid-19. To determine how the pandemic impacted the epidemiology of envenomations by those three groups of venomous animals, we used online databases from two surveillance sources on number of cases and mortality. During the years before and during the pandemic, scorpion stings typically occurred in adults of both sexes in urban zones in the Southeast and Northeast regions. Spider bites occurred mainly in the South region, in adults of both sexes in urban zone. Snakebites affected mainly rural adult men in the Amazon. Between 2007 and 2021, overall incidence of cases by scorpions, spiders and snakes decreased after the beginning of the pandemic, snakebites did not show changes after the pandemic started in Brazil, but cases by scorpions and spiders decreased. No changes in the incidence of deaths were observed. On national level, Covid-19 affected some demographic, clinical and epidemiological aspects in cases by scorpions, spiders and snakes.

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BACKGROUND: Loxoscelism is a toxic clinical condition caused by the bite of spiders of the genus Loxosceles, with wide distribution throughout the world.1 Phospholipase D is responsible for dermonecrosis, inflammation, platelet aggregation, hemolysis, alteration of vascular permeability, cytotoxicity, nephrotoxicity, acute renal failure, among other symptoms involved with this protein.
METHODS: 27-year-old male patient, who began with a sudden episode of intense pain in the right hand, in the metacarpus and metacarpophalangeal joints. On clinical examination, the upper extremity was noted to have increased volume, extensive edema, hyperemia, and increased local temperature; The lesion progressed to extensive necrosis. Fasciotomies were performed, from distal to proximal, and release of the second and third finger compartment through longitudinal radial and ulnar incisions. A skin autograft was placed, obtained from the anterior surface of the right thigh. Opioid analgesics, non-steroidal anti-inflammatory drugs, corticosteroids, and antibiotics were administered. The skin biopsy reported: inflammatory infiltrate with neutrophils, ulceration, and bacterial colonies. After 27 days he had a favorable evolution, so he was discharged to his home, with follow-up by staff from the Outpatient Service.
CONCLUSIONS: Cutaneous loxoscelism, as a cause of acute compartment syndrome of the hand, is rare, but should be considered in an area endemic for Loxosceles spp. Surgical decompression of the affected compartments represents a decisive factor in the treatment of patients.
BACKGROUND: El loxoscelismo es un cuadro clínico tóxico provocado por la mordedura de arañas del género Loxosceles, con amplia distribución en todo el mundo.1 La fosfolipasa D es la responsable de la dermonecrosis, inflamación, agregación plaquetaria, hemólisis, alteración de la permeabilidad vascular, citotoxicidad, nefrotoxicidad, insuficiencia renal aguda, entre otros síntomas implicados con esta proteína.
UNASSIGNED: Paciente masculino de 27 años, que inició con un cuadro repentino de dolor intenso en la mano derecha, en el metacarpo y las articulaciones metacarpofalángicas. Al examen clínico, la extremidad superior se percibió con aumento de volumen, edema extenso, hiperemia y aumento de la temperatura local; la lesión progresó a necrosis extensa. Se realizaron fasciotomías, de distal a proximal, y liberación del compartimento del segundo y tercer dedo a través de incisiones longitudinales radiales y cubitales. Se colocó un autoinjerto de piel, obtenido de la superficie anterior del muslo derecho. Se administraron analgésicos opioides, antiinflamatorios no esteroides, corticosteroides y antibióticos. La biopsia de piel reporto: infiltrado inflamatorio con neutrófilos, ulceración y colonias bacterianas. Luego de 27 días tuvo evolución favorable, por lo que se dio alta a su domicilio, con seguimiento por personal del servicio de Consulta externa.
UNASSIGNED: El loxoscelismo cutáneo, como causa de síndrome compartimental agudo de la mano, es poco común, pero debe considerarse en un área endémica para Loxosceles spp. La descompresión quirúrgica de los compartimentos afectados representa un factor decisivo en el tratamiento de los pacientes.

Envenomation by terrestrial toxic animals is considered a serious risk to human health worldwide. Snakes, hymenopterans, spiders, and scorpions have mainly attracted the attention of medical literature. However, the relative importance of spiders has been studied only in a few countries. Here, we present the first retrospective study on the incidence of spider bites requiring hospital care in Spain, compared to bites or stings from snakes, hymenopterans, and scorpions. Using ICD9MC and ICD10 databases from the World Health Organization\'s International Classification of Diseases for the period 1997-2020, we quantified the cases of envenomation by spiders, compared to those by other terrestrial toxic animals, the demographic data of envenomation cases, the relative severity of spider bites, and the geographic distribution of envenomation cases. Overall, the incidence of acute intoxication by terrestrial toxic animals in Spain was ca. 1.23 cases per million inhabitants. In decreasing order of importance, cases were due to snakes, hymenopterans, spiders, scorpions, and myriapods. Fatal cases were extremely rare, caused mainly by hymenopterans. No fatalities were caused by spiders, scorpions, and myriapods. A greater incidence of snake bites occurred in northern Spain, but no geographical trends were found for spider bites or scorpion stings. Severe poisoning or life-threatening cases due to bites or stings from toxic terrestrial animals in Spain seems to be very low, especially for spiders, compared to other countries in the world. In general, spiders do not present a risk to human health and should not be considered a major driver of morbidity.