Novel insights into the application of recombinant mutated phospholipases D as antigens for developing new strategies against Loxoscelism.

Loxoscelism is the pathological condition triggered by a brown spider bite. The venom of these spiders is rich in phospholipases D (PLDs), which can induce virtually all local and systemic manifestations. Recombinant mutated PLDs from clinically relevant Loxosceles species in South America have been investigated as potential antigens to develop novel therapeutic strategies for loxoscelism. However, certain gaps need to be addressed before a clinical approach can be implemented. In this study, we examined the potential of these recombinant mutated PLDs as antigens by testing some variations in the immunization scheme. Furthermore, we evaluated the efficacy of the produced antibodies in neutralizing the nephrotoxicity and sphingomyelinase activity of brown spider venoms. Our findings indicate that the number of immunizations has a greater impact on the effectiveness of neutralization compared to the amount of antigen. Specifically, two or three doses were equally effective in reducing dermonecrosis and edema. Additionally, three immunizations proved to be more effective in neutralizing mice lethality than one or two. Moreover, immunizations mitigated the signs of kidney injury, a crucial aspect given that acute renal failure is a serious systemic complication. In vitro inhibition of the sphingomyelinase activity of Loxosceles venoms, a key factor in vivo toxicity, was nearly complete after incubation with antibodies raised against these antigens. These findings underscore the importance of implementing an effective immunization scheme with multiple immunizations, without the need for high antigen doses, and enhances the spectrum of neutralization exhibited by antibodies generated with these antigens. In summary, these results highlight the strong potential of these antigens for the development of new therapeutic strategies against cutaneous and systemic manifestations of loxoscelism.

Protective effects of mesenchymal stromal cell-derived secretome on dermonecrosis induced in rabbits by Loxosceles intermedia spider venom.

Background: Loxoscelism refers to a set of clinical manifestations caused by the bite of spiders from the Loxosceles genus. The classic clinical symptoms are characterized by an intense inflammatory reaction at the bite site followed by local necrosis and can be classified as cutaneous loxoscelism. This cutaneous form presents difficult healing, and the proposed treatments are not specific or effective. This study aimed to evaluate the protective effect of mesenchymal stromal cells-derived secretome on dermonecrosis induced by Loxosceles intermedia spider venom in rabbits. Methods: Sixteen rabbits were distributed into four groups (n = 4). Except for group 1 (G1), which received only PBS, the other three groups (G2, G3, and G4) were initially challenged with 10 µg of L. intermedia venom, diluted in 100 µL of NaCl 0.9%, by intradermic injection in the interscapular region. Thirty minutes after the challenge all groups were treated with secretome, except for group 2. Group 1 (G1-control group) received intradermal injection (ID) of 60 µg of secretome in 0.15 M PBS; Group 2 (G2) received 0.9% NaCl via ID; Group 3 (G3) received 60 µg of secretome, via ID and Group 4 (G4), received 60 µg of secretome by intravenous route. Rabbits were evaluated daily and after 15 days were euthanized, necropsied and skin samples around the necrotic lesions were collected for histological analysis. Results: Rabbits of G1 did not present edema, erythema, hemorrhagic halo, or necrosis. In animals from G2, G3, and G4, edema appeared after 6h. However, minor edema was observed in the animals of G2 and G3. Hemorrhagic halo was observed in animals, six hours and three days after, on G2, G3, and G4. Macroscopically, in G4, only one animal out of four had a lesion that evolved into a dermonecrotic wound. No changes were observed in the skin of the animals of G1, by microscopic evaluation. All animals challenged with L. intermedia venom showed similar alterations, such as necrosis and heterophilic infiltration. However, animals from G4 showed fibroblast activation, early development of connective tissue, neovascularization, and tissue re-epithelialization, indicating a more prominent healing process. Conclusion: These results suggest that secretome from mesenchymal stromal cells cultured in a xeno-free and human component-free culture media can be promising to treat dermonecrosis caused after Loxosceles spiders bite envenoming.

Binding of green tea epigallocatechin gallate to the arginine kinase active site from the brown recluse spider (Loxosceles laeta): A potential synergist to chemical pesticides.

Loxosceles spp. spiders can cause serious public health issues. Chemical control is commonly used, leading to health and environmental problems. Identifying molecular targets and using them with natural compounds can help develop safer and eco-friendlier biopesticides. We studied the kinetics and predicted structural characteristics of arginine kinase (EC 2.7.3.3) from Loxosceles laeta (LlAK), a key enzyme in the energy metabolism of these organisms. Additionally, we explored (-)-epigallocatechin gallate (EGCG), a green tea flavonoid, as a potential lead compound for the LlAK active site through fluorescence and in silico analysis, such as molecular docking and molecular dynamics (MD) simulation and MM/PBSA analyses. The results indicate that LlAK is a highly efficient enzyme (K m Arg 0.14 mM, K m ATP 0.98 mM, k cat 93 s-1, k cat/K m Arg 630 s-1 mM-1, k cat/K m ATP 94 s-1 mM-1), which correlates with its structure similarity to others AKs (such as Litopenaeus vannamei, Polybetes pythagoricus, and Rhipicephalus sanguineus) and might be related to its important function in the spider's energetic metabolism. Furthermore, the MD and MM/PBSA analysis suggests that EGCG interacted with LlAK, specifically at ATP/ADP binding site (RMSD <1 nm) and its interaction is energetically favored for its binding stability (-40 to -15 kcal/mol). Moreover, these results are supported by fluorescence quenching analysis (K d 58.3 µM and K a 1.71 × 104 M-1). In this context, LlAK is a promising target for the chemical control of L. laeta, and EGCG could be used in combination with conventional pesticides to manage the population of Loxosceles species in urban areas.

Necrotic ulcers caused by Loxosceles rufescens bites: a report of seven patients and scanning electron microscopy of the spider.

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.

A brown recluse spider bite wound: a case report and literature review.

DECLARATION OF INTEREST: The authors have no conflicts of interest.

Loxosceles amazonica Brown Spider venom: Insights into enzymatic activities, immunorecognition, and novel phospholipase D isoforms.

The Loxosceles genus represents one of the main arachnid genera of medical importance in Brazil. Despite the gravity of Loxosceles-related accidents, just a handful of species are deemed medically important and only a few have undergone comprehensive venom characterization. Loxosceles amazonica is a notable example of a potentially dangerous yet understudied Loxosceles species. While there have been limited reports of accidents involving L. amazonica to date, accidents related to Loxosceles are increasing in the North and Northeast regions of Brazil, where L. amazonica has been reported. In this work, we provide a complementary biochemical and immunological characterization of L. amazonica venom, considering its most relevant enzymatic activities and its immunorecognition and neutralization by current therapeutic antivenoms. Additionally, a cDNA library enriched with phospholipase D (PLD) sequences from L. amazonica venom glands was built and subsequently sequenced. The results showed that L. amazonica venom is well immunorecognised by all the tested antibodies. Its venom also displayed proteolytic, hyaluronidase, and sphingomyelinase activities. These activities were at least partially inhibited by available antivenoms. With cDNA sequencing of PLDs, seven new putative isoforms were identified in the venom of L. amazonica. These results contribute to a better knowledge of the venom content and activities of a synanthropic, yet understudied, Loxosceles species. In vivo assays are essential to confirm the medical relevance of L. amazonica, as well as to assess its true toxic potential and elucidate its related pathophysiology.

[Loxoscelism with acute compartment síndrome: A case report with successful conclusion]. / Loxoscelismo con síndrome compartimental agudo: reporte de un caso con desenlace exitoso.

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. CASE REPORT: 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. CONCLUSION: 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.

ANTECEDENTES: 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. REPORTE DE CASO: 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. CONCLUSIÓN: 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.

Role of the complement system in kidney cell death induced by Loxosceles venom Sphingomyelinases D.

Envenomation by Loxosceles spiders can result in local and systemic pathologies. Systemic loxoscelism, which can lead to death, is characterized by intravascular hemolysis, platelet aggregation, and acute kidney injury. Sphingomyelinase D (SMase D) in Loxosceles spider venom is responsible for both local and systemic pathologies, and has been shown to induce metalloprotease activity. As the complement system is involved in many renal pathologies and is involved in hemolysis in systemic loxoscelism, the aim of this study was to investigate its role and the role of complement regulators and metalloproteases in an in vitro model of Loxosceles venom induced renal pathology. We investigated the effects of the venom/SMase D and the complement system on the HK-2 kidney cell line. Using cell viability assays, western blotting, and flow cytometry, we show that human serum, as a source of complement, enhanced the venom/SMase D induced cell death and the deposition of complement components and properdin. Inhibitors for ADAM-10 and ADAM-17 prevented the venom induced release of the of the complement regulator MCP/CD46 and reduced the venom/SMase D induced cell death. Our results show that the complement system can contribute to Loxosceles venom induced renal pathology. We therefore suggest that patients experiencing systemic loxoscelism may benefit from treatment with metalloproteinase inhibitors and complement inhibitors, but this proposition should be further analyzed in future pre-clinical and clinical assays.

Discovery of broadly-neutralizing antibodies against brown recluse spider and Gadim scorpion sphingomyelinases using consensus toxins as antigens.

Broadly-neutralizing monoclonal antibodies are becoming increasingly important tools for treating infectious diseases and animal envenomings. However, designing and developing broadly-neutralizing antibodies can be cumbersome using traditional low-throughput iterative protein engineering methods. Here, we present a new high-throughput approach for the standardized discovery of broadly-neutralizing monoclonal antibodies relying on phage display technology and consensus antigens representing average sequences of related proteins. We showcase the utility of this approach by applying it to toxic sphingomyelinases from the venoms of species from very distant orders of the animal kingdom, the recluse spider and Gadim scorpion. First, we designed a consensus sphingomyelinase and performed three rounds of phage display selection, followed by DELFIA-based screening and ranking, and benchmarked this to a similar campaign involving cross-panning against recombinant versions of the native toxins. Second, we identified two scFvs that not only bind the consensus toxins, but which can also neutralize sphingomyelinase activity of native whole venom in vitro. Finally, we conclude that the phage display campaign involving the use of the consensus toxin was more successful in yielding cross-neutralizing scFvs than the phage display campaign involving cross-panning.

Utilization of dapsone and hemoglobin in the epithelial skin regeneration therapy of cutaneous loxoscelism: A case report and integrative literature review

ABSTRACT BACKGROUND: Loxosceles spp are arthropods found worldwide. Its bite may produce cutaneous loxoscelism (necrotic or edematous) or cutaneous-visceral loxoscelism. Depending on their severity and location, cutaneous forms are managed with local cold application and systemic administration of antihistamines, corticosteroids, antibiotics, polymorphonuclear inhibitors, and analgesics. OBJECTIVE: This study aimed to report a case of cutaneous loxoscelism and to identify the main dermatological manifestations associated with the Loxosceles spp bite. DESIGN AND SETTING: This case report and literature review was conducted in a Mexican university. METHODS: A detailed report on the medical management of a patient with cutaneous loxoscelism treated at the emergency department of a public hospital was published. Scopus, PubMed, Web of Science, and Google Scholar databases were searched to identify articles reporting cutaneous loxoscelism. The following keywords were used during the database search: "loxoscelism" OR "spider bite," OR "loxosceles" OR "loxosceles species" OR "loxosceles venom" OR "loxoscelism case report" AND "cutaneous" OR "dermonecrotic arachnidism." RESULTS: A 62-year-old female patient with cutaneous loxoscelism was treated with systemic dapsone and local heparin spray. Eighteen studies with 22 clinical cases were included in this systematic review. Of the 22 patients, 12 (54.5%) were men. L. rufescens was the predominant spider species. CONCLUSIONS: The administration of dapsone and heparin for the management of cutaneous loxoscelism demonstrated success in this case, with no sequelae observed. In general, the literature review indicated favorable outcomes in patients treated with antimicrobials and corticosteroids, with continuous healing of skin lesions. SYSTEMATIC REVIEW REGISTRATION: PROSPERO ID CRD42023422424 (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023422424).

Clinical Evolution After Administering Antivenom in Patients With Loxoscelism.

Spiders are the most numerous arthropods of the arachnid class. More than 45 thousand species of spiders have been identified, and only a few are dangerous to humans. Among them, the "violin spider" or "brown spider" of the genus Loxosceles (family Sicariidae) has a worldwide distribution, and its bite can cause loxoscelism. Initial treatment of a Loxosceles spider bite includes application of local cold, rest, elevation of the extremity if possible, and systemic pharmacotherapy with antihistamines, corticosteroids, antibiotics, polymorphonuclear inhibitors, and analgesics or nonsteroidal anti-inflammatory drugs. During cutaneous or systemic loxoscelism, administration of Loxosceles antivenom (immunoglobulin (Ig)G F(ab')2 fragments) may be indicated to prevent progression to severe systemic phases. In this manuscript, we present three cases of patients with loxoscelism treated with the fabotherapeutic Reclusmyn®, developed and manufactured in Mexico. Two patients had a satisfactory outcome without severe skin or systemic damage. Only one patient with loxoscelism, despite early initiation of antivenom, had extensive skin lesions that healed satisfactorily, leaving only a non-disabling scar. Due to the global presence of this clinical problem, further studies are needed to establish local and general guidelines for the treatment and prevention of loxoscelism. This will allow health professionals to provide more efficient and higher quality medical care and feel supported in their decisions.

Comparative Biochemical, Structural, and Functional Analysis of Recombinant Phospholipases D from Three Loxosceles Spider Venoms.

Spiders of Loxosceles genus are widely distributed and their venoms contain phospholipases D (PLDs), which degrade phospholipids and trigger inflammatory responses, dermonecrosis, hematological changes, and renal injuries. Biochemical, functional, and structural properties of three recombinant PLDs from L. intermedia, L. laeta, and L. gaucho, the principal species clinically relevant in South America, were analyzed. Sera against L. gaucho and L. laeta PLDs strongly cross-reacted with other PLDs, but sera against L. intermedia PLD mostly reacted with homologous molecules, suggesting underlying structural and functional differences. PLDs presented a similar secondary structure profile but distinct melting temperatures. Different methods demonstrated that all PLDs cleave sphingomyelin and lysophosphatidylcholine, but L. gaucho and L. laeta PLDs excelled. L. gaucho PLD showed greater "in vitro" hemolytic activity. L. gaucho and L. laeta PLDs were more lethal in assays with mice and crickets. Molecular dynamics simulations correlated their biochemical activities with differences in sequences and conformations of specific surface loops, which play roles in protein stability and in modulating interactions with the membrane. Despite the high similarity, PLDs from L. gaucho and L. laeta venoms are more active than L. intermedia PLD, requiring special attention from physicians when these two species prevail in endemic regions.

Identification of a common epitope in knottins and phospholipases D present in Loxosceles sp venom by a monoclonal antibody.

In the Americas and specially in Brazil, the Loxosceles intermedia, Loxosceles gaucho and Loxosceles laeta are the three most medically relevant brown spider species, and whose bites can lead to the condition known as loxoscelism. Here, we report the development of a tool capable of identifying a common epitope amongst Loxosceles sp. venom's toxins. A murine monoclonal antibody (LmAb12) and its recombinant fragments (scFv12P and diabody12P) have been produced and characterized. This antibody and its recombinant constructs were able to recognize proteins of Loxosceles spider venoms with specificity. The scFv12P variant was also able to detect low concentrations of Loxosceles venom in a competitive ELISA assay, displaying potential as a venom identification tool. The primary antigenic target of LmAb12 is a knottin, a venom neurotoxin, that has a shared identity of 100 % between the L. intermedia and L. gaucho species and high similarity to L. laeta. Furthermore, we observed LmAb12 was able to partially inhibit in vitro hemolysis, a cellular event typically induced by the Loxosceles sp. venoms. Such behavior might be due to LmAb12 cross-reactivity between the antigenic target of LmAb12 and the venom's dermonecrotic toxins, the PLDs, or even the existence of synergism between these two toxins.

Partial characterization of Loxosceles anomala (Mello-Leitão, 1917) venom: A brown spider of potential medical concern.

The spider's genus Loxosceles (also known as "brown spiders") is one of the few ones of medical importance in Brazil, being Loxosceles anomala a species of common occurrence in the Southeast region. This species is usually smaller in size than the other members of the Loxosceles group. A single human accident involving L. anomala was reported to date and the clinical picture shared similar characteristics with accidents caused by other Loxosceles species. Despite the potential relevance of L. anomalafor loxocelism in Minas Gerais state, its venom activity has never been characterized. In this work, we provide a preliminary characterization of L. anomala venom, considering its most relevant enzymatic activities and its venom immunorecognition by current therapeutic antivenoms. The results showed that L. anomala venom is immunorecognised by therapeutic antivenoms and by anti-phospholipase D antibodies. Its venom also shows enzymatic activities (sphingomyelinase activity, fibrinogenolytic) described for other Loxosceles venoms. This work contributes to a better knowledge on the venom content and activities of synanthropic Loxosceles species that have the potential of causing relevant human accidents.

Brown Spider Venom Phospholipase-D Activity upon Different Lipid Substrates.

Brown spider envenomation results in dermonecrosis, characterized by an intense inflammatory reaction. The principal toxins of brown spider venoms are phospholipase-D isoforms, which interact with different cellular membrane components, degrade phospholipids, and generate bioactive mediators leading to harmful effects. The Loxosceles intermedia phospholipase D, LiRecDT1, possesses a loop that modulates the accessibility to the active site and plays a crucial role in substrate. In vitro and in silico analyses were performed to determine aspects of this enzyme's substrate preference. Sphingomyelin d18:1/6:0 was the preferred substrate of LiRecDT1 compared to other Sphingomyelins. Lysophosphatidylcholine 16:0/0:0 was preferred among other lysophosphatidylcholines, but much less than Sphingomyelin d18:1/6:0. In contrast, phosphatidylcholine d18:1/16:0 was not cleaved. Thus, the number of carbon atoms in the substrate plays a vital role in determining the optimal activity of this phospholipase-D. The presence of an amide group at C2 plays a key role in recognition and activity. In silico analyses indicated that a subsite containing the aromatic residues Y228 and W230 appears essential for choline recognition by cation-π interactions. These findings may help to explain why different cells, with different phospholipid fatty acid compositions exhibit distinct susceptibilities to brown spider venoms.

Evaluation of the effects of Loxosceles intermedia's venom in zebrafish.

The zebrafish is an animal model of increasing use in many biomedical fields of study, including toxicology, inflammation, and tissue regeneration. In this paper, we have investigated the inflammatory effects of Loxosceles intermedia's venom (LIV) on zebrafish, as well as the effects of Maresin 2 (Mar2) and Resolvin D5 (RvD5), two specialized pro-resolving mediators (SPMs), in the context of tissue regeneration after fin fold amputation. Furthermore, increasing concentrations of LIV (250-2000 ng) were assayed for their haemolytic effects in vitro, and, afterwards, the same concentrations were evaluated in vivo, when injected intraperitoneally. LIV caused haemolysis in human red blood cells (RBCs), but not in zebrafish RBCs. The survival curve was also not altered by LIV injection, regardless of venom dosage. Histological analysis of renal and hepatic tissues, as well as the whole animal, revealed no pathological differences between LIV-injected and PBS-injected groups. Fin fold regeneration was not altered between LIV-injected and control groups, nor in the presence of MaR2 and RvD5. Results of swimming behavioral analysis also did not differ between groups. Moreover, in silico data indicated differences between human and zebrafish cell membrane lipid constitutions, such as in phospholipases D preferred substrates, that could lead to the protection of zebrafish against LIV. Although our data implies that zebrafish cannot be used as a toxicological model for LIV studies, the absence of observed toxicological effects paves the way for the comprehension of the venom's mechanism of action in mammals and the fundamental evolutionary processes involved.

Factores asociados al conocimiento y medidas preventivas de mordedura de Loxosceles laeta en la población de la Encuesta Nacional de Programas Presupuestales (ENAPRES) en el Perú 2017-2019 / Factors associated with knowledge and preventive measures of Loxosceles laeta bite in the population of the National Survey of Budgetary Programs (ENAPRES) in Peru 2017-2019

INTRODUCCIÓN: Las enfermedades metaxénicas y zoonóticas, son consideradas prioridades nacionales de investigación en salud en Perú 2019-2023. De estas, los casos reportados por loxoscelismo han ido aumentando progresivamente. OBJETIVO: Determinar los factores asociados al conocimiento y medidas preventivas de mordedura de Loxosceles laeta en la población de la ENAPRES en el Perú 2017-2019. MÉTODOS: Estudio de tipo observacional, transversal, analítico y retrospectivo, basado en la información de la ENAPRES. RESULTADOS: Se analizó una muestra total de 285.354 personas. De estas, aquellos con 60 a más años (RPa=1,48; IC95%: 1,45-1,51), los costeños (RPa=1,37; IC95%: 1,33-1,40), las mujeres (RPa=1,12; IC95%: 1,11-1,13), con primaria o secundaria (RPa=1,12; IC95%: 1,09-1,15), con viviendas inadecuadas [techo (RPa=1,07; IC95%: 1,05-1,10), piso (RPa=1,02; IC95%: 1,00-1,04)], se asociaron con mayor posibilidad de tener más conocimiento sobre mordedura de L. laeta. Por otra parte, los encuestados de 60 a más años (RPa=1,49; IC95%: 1,46-1,52), los costeños (RPa=1,39; IC95%: 1,35-1,43), con estudios superiores no universitarios (RPa=1,19; IC95%: 1,15-1,22), las mujeres (RPa=1,13; IC95%: 1,12-1,14) y con viviendas con techos inadecuados (RPa=1,07; IC95%: 1,05-1,10) se asociaron con mayor posibilidad de realizar adecuadas medidas preventivas. En ambas, se halló asociación con el desechar los residuos orgánicos en calle o vía pública (RPa=0,97; IC95%: 0,96-0,99). CONCLUSIONES: Se encontró aquellos factores asociados a conocimientos y a las medidas preventivas de mordedura de L. laeta.

BACKGROUND: Metaxenic and zoonotic diseases are one of the ten national priorities for health research in Peru 2019-2023. Of these, the cases reported by loxoscelism have been increasing progressively. AIM: To determine the factors associated with the knowledge and preventive measures of Loxosceles laeta bite in the population of the ENAPRES in Peru 2017-2019. METHODS: Observational, cross-sectional, analytical and retrospective study, based on information from ENAPRES. RESULTS: A total sample of 285,354 people was analyzed. Of these, those aged 60 or over (PRa=1,48; 95%CI: 1,45-1,51), those from the coast (PRa=1,37; 95%CI: 1,33-1,40), women (PRa=1,12; 95%CI: 1,11-1,13), with primary or secondary education (PRa=1,12; 95%CI: 1,09-1,15), with inadequate housing [ceiling (PRa=1,07; 95%CI: 1,05-1,10), floor (PRa=1,02; 95%CI: 1,00-1,04)], were associated with higher possibility ofhaving more knowledge about L. laeta bite. On the other hand, those aged 60 or over (PRa=1,49; 95%CI: 1,46-1,52), those from the coast (PRa=1,39; 95%CI: 1,35-1,43), with non-university higher education (PRa=1,19; 95%CI: 1,15-1,22), women (PR a=1,13; 95%CI: 1,12-1,14) and with inadequate housing ceilings (PRa=1,07; 95%CI 1,05-1,10) were associated with a greater possibility of taking adequate preventive measures. In both, an association was found between disposing of organic waste on the street or on public roads (RPa=0.97; 95%CI: 0.96-0.99) CONCLUSIONS: It were found factors associated with knowledge and preventive for L. laeta bite.

Primer registro de un caso de loxoscelismo cutáneo ocasionado por mordedura de araña violinista (Loxosceles yucatana) en Yucatán, México / First record of a case of cutaneous loxoscelism caused by violin spider (Loxosceles yucatana) bite in Yucatan, Mexico

El loxoscelismo es ocasionado cuando el veneno dermonecrótico producido por las arañas del género Loxosceles, conocidas como «arañas violinistas», ingresa al organismo de una persona a través de su mordida. En México ocurre un subregistro de los casos de loxoscelismo por la ausencia de pruebas de laboratorio para su diagnóstico y la dificultad del cuadro clínico. El objetivo de este trabajo es describir un caso de loxoscelismo cutáneo ocasionado por mordedura de Loxosceles yucatana en un residente de Yucatán, México. El loxoscelismo cutáneo es el tipo más frecuente y menos severo. El presente caso se diagnosticó por medio de la sintomatología registrada en la historia clínica, la lesión inicial y la identificación de arañas L. yucatana. Este trabajo representa la primera descripción de un caso de loxoscelismo cutáneo con resolución favorable en Yucatán.

Loxoscelism occurs when the dermonecrotic venom produced by spiders of the genus Loxosceles, known as "violin spiders," enters a person's organism through their bite. In Mexico there is an underreporting of loxoscelism cases due to the absence of laboratory tests for its diagnosis and the complexity of the clinical picture. The aim of this paper is to describe a case of cutaneous loxoscelism caused by the bite of Loxosceles yucatana in a resident of Yucatan, Mexico. Cutaneous loxoscelism is the most frequent and less severe type. This case was diagnosed by means of the symptomatology registered in the medical records, the initial lesion, and the identification of L. yucatana spiders. This study represents the first description of a case of cutaneous loxoscelism with favorable outcome in Yucatan.

Venomous spiders of Albania -does an increase of temperature influence the toxicity of spider venom?

Black widow spiders (Latrodectus sp.) are distributed worldwide, and in Albania the L. tredecimguttatus Rossi, 1790 has been the dominant spider. Other medically important spiders in Albania include the brown recluse with symptoms known as loxoscelism, the false black widow and the egg sac spiders; the last two inducing similar symptoms to a wasp sting. METHODS: The data analyzed is from a decade-long study of 125 patients hospitalized in the regional hospital of Fier County, in the Western Lowland of Albania from May 2009 and to October 2018. OBJECTIVE: Although the venom is rarely fatal, the recent spider bites raise questions about the influence of higher air temperatures on their possibly increased toxicity. RESULTS: Significantly the severity of the α-latrotoxin rises during the summer, when human-spider contact frequency is higher and when the black widow spiders have an increased motivation to protect their egg sacs. CONCLUSION: This study revealed an increased severity of the black widow bites with respect to patient health, shown via all the severe systemic symptoms, during those months with higher temperatures.

Brown Recluse Spider Bite Resulting in Coombs Negative Hemolytic Anemia in a Young Male Requiring Blood Transfusion.

Spider bites, including the bites of recluse spiders (Loxosceles, also known as brown spiders), usually lead to local symptoms; however, severe systemic symptoms have also been reported in the literature. Management of spider bites is based on symptoms. In severe cases involving the development of angioedema, hemolytic anemia, skin necrosis with superimposed bacterial infection or disseminated intravascular coagulation, antibiotics, steroids, blood transfusions, and plasma exchange may also play a role. We present a case of a brown recluse spider bite resulting in symptomatic hemolytic anemia and jaundice requiring blood transfusion.