Primer registro de una picadura causada por un macho de Latrodectus geometricus C. L. Koch, 1841 (Araneae: Theridiidae) / First record of a bite produced by a male of Latrodectus geometricus C. L. Koch, 1841 (Araneae: Theridiidae)

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 terapéutica. 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 disminuyó 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.

Latrodectus geometricus (Araneae: Theridiidae) is a spider commonly known as "Brown widow". Originally from Africa, is a synanthropic and cosmopolitan spider, very common in several cities in central and northern Argentina. Unlike other species of the genus, this spider does not cause serious poisoning, very few have been registered that required treatment and always evolved favorably. All cases listed to date were attributed to females, assuming that males do not cause clinical cases and would even be unable to pass through human skin due to the small size of their chelicerae. This work presents the first record of an accident by a male of L. geometricus and describes the symptoms. The accident occurred to a 21 year old woman from Villa Gobernador Gálvez (33°01'31" S, 60°38'01" W), Santa Fe, Argentina, in March 2016. The specimen died at the time, being preserved and then identified as an adult male of L. geometricus according to its genitalia. The symptoms were relieved from the accident to its end without applying treatments. At the time, the woman felt a sting followed immediately by burning sensation and erythema in the area. After 10 minutes the burning increased, decreasing at 20 minutes. One hour later, burning sensation disappeared and the erythema diminished considerably. The observed results support L. geometricus as not dangerous in Argentina and show that males actually are able to penetrate the human skin, at least in areas of thin skin.

Prospective cohort study of definite spider bites in Australian children.

OBJECTIVES: To describe the clinical effects of spider bites in a paediatric population and compare to bites in an adult population. METHODS: Prospective follow up study of children with definite spider bites where the spiders were immediately collected and expertly identified. Cases were recruited from Australian emergency departments and poison information centres and followed up. Data were collected on circumstances of bites and clinical effects, and compared with similar data from adult spider bites. RESULTS: There were 163 cases (62% male, 38% female; age <16, median age 7 years, interquartile range (IQR): 3-11 years). The median duration of effects was 2 h (IQR 0.25-12 h). The commonest spiders were Huntsman spiders (Sparassidae) and Orb weavers (Araneidae), and comparatively few bites by theridiid spiders, including Red-back spiders. Pain or discomfort occurred in all bites and was severe in 20%. Local effects included puncture marks/bleeding (36%) and red mark/redness (73%). Systemic effects occurred in only 6% of cases. There were no necrotic lesions or ulcers as a consequence of any spider bites (0%; 97.5% CI 0.0-2.2%) and no early allergic reactions or secondary infections. The median duration of clinical effects was shorter than adults, the frequency of severe pain was less than adults and systemic effects were less common in children. CONCLUSIONS: Paediatric spider bite causes minor effects in the majority of cases, and is unlikely to cause necrotic ulcers, allergic reactions or infection. The severity and duration of effects differ from adults.

Developing a decision tree algorithm for the diagnosis of suspected spider bites.

OBJECTIVE: To develop a diagnostic algorithm (decision tree) to improve the ability to identify or predict medically important spider bites (funnel-web and redback spiders) from information about the circumstances and initial clinical effects of spider bites. METHODS: A dataset of definite spider bites with expert identification of all spiders was used from a previous Australia-wide prospective study. Spider bites were categorized as: big black spider (BBS), redback spider (RED) and other spider (OTH). Big black spider included funnel-web spiders (most medically significant), but also other spiders of similar appearance. Fifteen predictor variables were based on univariate analysis from previous studies and clinical experience. They included information about the circumstances and early clinical effects of bites. The data were analyzed using CART (Classification and Regression Trees), a 'decision tree' algorithm used to create a tree-like structure to describe a data set. RESULTS: Of 789 spider bites there were 49 (6.2%) bites by BBS, 68 (8.6%) bites by RED and 672 (85.2%) bites by OTH. A decision tree was developed that included six predictor variables (fang marks/bleeding; state/territory; local diaphoresis; month; time of day; and proximal or distal bite region). The decision tree accurately classified 47 out of the 49 (96%) BBS, and no funnel-web spiders were incorrectly classified (100% sensitivity). Two hundred and forty-four of 789 were classified as OTH and included no BBS. CONCLUSIONS: A decision tree based on a small amount of information about the circumstances and early clinical effects of spider bites safely predicted all funnel-web spider bites. Application of this algorithm would allow the early institution of appropriate treatment for funnel-web spider bites and the immediate discharge of 31% as other spider bites (reassurance only).

The kinin system in the envenomation caused by the Tityus serrulatus scorpion sting.

Several lines of evidence in experimental animals indicate that the kinin system may participate in the pathogenesis of envenomation by the Tityus serrulatus (Ts) scorpion sting, but there are no studies in humans with regard to this system. In this study, we evaluated the plasma levels of high-molecular (HKg) and low-molecular (LKg) weight kininogens (detected by ELISA), the activities of plasma or tissue kallikreins and kininase II (enzymatic action upon selective substrates), and the Ts plasma venom levels (ELISA). A total of 27 patients (12 males) aged 12-72 were evaluated immediately at hospital admittance. According to the severity of envenomation, patients were classified as mild (n = 15), moderate (n = 8), and severe cases (n = 4). Controls were paired for age and sex. Plasma venom levels were associated with the severity of envenomation. Severe cases presented lower levels of LKg in relation to mild and controls. Inverse correlations were seen between LKg levels and the venom concentration. The results of this study suggested that the kinin system may participate in the pathogenesis of human Ts envenomation and knowledge about this system may be useful to develop new strategies to reduce the damage caused by scorpion envenomation.

Loxoscelismo en pediatría: Región Metropolitana Chile / Loxoscelism in paediatrics: Región Metropolitana Chile

Loxoscelismo es el cuadro tóxico producido por veneno que arañas del género Loxosceles L. Iaeta, en Chile, inyectan en el momento de la mordedura. Puede presentarse en dos formas clínica: loxoscelismo cutáneo-visceral (LCV). El objetivo del presente trabajo es exponer y analizar los aspectos clínico-epidemiológicos de 56 casos pediátrico -38 LC y 18 LCV- atendidos en la Región Metropolitana. En los últimos 45 años se ha encontrado una mayor incidencia de ambas formas en primavera-verano, en dormitorios cuando el niño dormía o se estaba vistiendo, siendo las áreas cutáneas más frecuentemente afectadas las extremidades y cara, con sensación de lancetazo urente como síntoma inicial. Manifestaciones clínicas más frecuentes: dolor, edema y placa livedoide que derivó a escara necrótica. Manifestaciones clínicas del LCV fueron hematuria, hemoglobinuria, ictericia, fiebre y compromiso de conciencia; letalidad 22,2 por ciento. El LCV no tuvo relación con el sitio de mordedura, extensión de la lesión local ni época del año. Si el compromiso visceral no aparece en las primeras 24 h es muy probable que se trate de un LC cuyo pronóstico es bueno. Si el paciente con LCV ha sobrepasado las 48 h, sus posibilidades de recuperación son altas. El tratamiento fue parental: antihistamínicos o corticoides en LC y corticoides en LCV. Conclusiones: En esta serie se observa una predominancia en el sexo femenino, sin diferencias estacionales ni de edad. En su gran mayoría los casos se originaron en el domicilio, afectando en especial las extremidades. El LCV fue más frecuente en mujeres, y sus principales manifestaciones fueron la hematuria y hemoglobinuria, y la precocidad del diagnóstico y su manejo son factores fundamentales en el pronóstico

A controlled trial of topical nitroglycerin in a New Zealand white rabbit model of brown recluse spider envenomation.

STUDY OBJECTIVES: Topical nitroglycerin has been reported to prevent skin necrosis from brown recluse spider bites, but this has never been scientifically tested. This study attempts to assess the effects of topical nitroglycerin on experimental Loxosceles reclusa envenomations. METHODS: We performed a randomized, blinded, controlled study in an animal care facility. Twenty-four New Zealand white rabbits were experimentally envenomated by means of subcutaneous injection with 20 microg of brown recluse spider venom. Rabbits were randomized to 1 of 2 experimental groups. The treatment group received 1 in of 2% topical nitroglycerin ointment every 6 hours for 3 days applied directly to the envenomation site. The control group received the vehicle without nitroglycerin. Gross examination of the lesions and measurements of the areas of the lesions were made daily. Creatine phosphokinase (CPK), blood urea nitrogen, creatinine, hemoglobin, and hematocrit levels were measured on days 0, 5, and 10. Lesions were excised after 10 days and examined by a blinded pathologist, who measured the area of necrosis and quantified inflammation and edema using a standard wound-healing score. For all values, mean values plus SD were determined. All comparisons made over multiple time points were assessed for significance by using a repeated-measures analysis of variance followed by Fisher least significant difference and Scheffé post hoc comparisons. A P value of.05 or less was used to determine significance. The Student's t test was used to compare the means of single measures. Significance was determined by using 95% confidence intervals. Comparisons of total area of necrosis were made with the nonparametric Mann-Whitney U test because of the heavy positive skew of the data. RESULTS: Skin necrosis developed in all animals. Mean values of the lesion area were not significantly different over time between the 2 groups of animals. At day 10, the median area of necrosis was 22.3 cm2 for the treatment group and 15.4 cm2 for the control group (P =.12). The inflammation score was 3.33+/-0.78 for the treatment group and 2.79+/-1.29 for the control group (P < .01). The edema score was 1.25+/-1.28 for the treatment group and 0.98+/-1.10 for the control group (not significantly different). CPK levels increased dramatically in both groups, with the greatest increase in the treatment group. In both groups hemoglobin and hematocrit levels decreased significantly, whereas WBC counts and platelet counts increased significantly, without significant differences between the 2 groups. CONCLUSION: At the dose used in this experiment, topical nitroglycerin did not prevent skin necrosis, increased inflammation score, and increased serum CPK levels. The results of this study do not support the use of topical nitroglycerin in the treatment of L reclusa envenomation and suggest that systemic toxicity could be increased.

Severe scorpion envenomation in Brazil: clinical laboratory and anatomopathological aspects

Os acidentes escorpionicos no Brasil, assumem grande importancia nao so pela sua incidencia como pela sua potencialidade em induzir quadros clinicos graves, muitas vezes fatais, principalmente em criancas. Apresentamos neste relato os dados clinicos e laboratoriais de 4 pacientes vitimas de escorpionismo, causado pelo T. serrulatus, que evoluiram com falencia cardiaca e edema pulmonar, sendo que tres foram a obito dentro das primeiras 24 horas apos acidente...

Clinical presentation and treatment of black widow spider envenomation: a review of 163 cases.

STUDY OBJECTIVE: To review cases of black widow spider envenomation to describe the clinical presentation and evaluate the efficacy of treatment. DESIGN: Retrospective chart review. SETTING: An urban toxicology referral center. TYPE OF PARTICIPANTS: All patients attended by the toxicology service and discharged from our hospital between January 1982 and December 1990 with a diagnosis of black widow spider envenomation. INTERVENTIONS: Inclusion criteria were either a positive black widow spider identification or a visible envenomation site ("target lesion"). Depending on the clinical presentation, patients were categorized as grade 1, 2, or 3 in severity. The efficacy and side effects of treatment alternative were evaluated. MEASUREMENTS AND MAIN RESULTS: One hundred sixty-three patients met the inclusion criteria. The most common sites of envenomation were the upper and lower extremities. The most common presenting complaint was generalized abdominal, back, and leg pain. One hundred eighteen patients initially presented to our institution, and 45 were transfers. Pain relief of grade 2 and 3 envenomations was achieved most effectively with either black widow spider-specific antivenin alone or a combination of IV opioids and muscle relaxants. Fifty-eight patients received antivenin with complete resolution of symptoms in a mean time of 31 +/- 26.7 minutes. Of the 118 patients initially seen at our institution, the mean total duration of symptoms was 9 +/- 22.7 hours in patients receiving antivenin and 22 +/- 24.9 hours in patients not receiving antivenin. Fifty-two percent of patients not receiving antivenin required hospitalization, whereas only 12% of those receiving antivenin were admitted. One patient died of severe bronchospasm after receiving antivenin. Calcium gluconate was not effective in providing symptomatic relief in this series, with 96% of the grade 2 and 3 envenomations treated initially with calcium gluconate requiring the addition of IV opioids or other analgesics for symptomatic relief. Fifty-five percent of patients initially receiving IV morphine and 70% of those initially receiving both IV morphine and benzodiazepines obtained symptomatic relief without additional medication. CONCLUSION: One hundred sixty-three envenomations by black widow spiders were reviewed and graded according to severity with treatment modalities evaluated. Although calcium gluconate usually has been considered the first-line treatment of severe envenomations by black widow spiders, we found it ineffective for pain relief compared with a combination of IV opioids and benzodiazepines. The use of antivenin significantly shortened the duration of symptoms in severe envenomations.

Presumed arachnidism. A case report (in Connecticut).

An 8-year-old boy with multiple (up to 12) hemorrhagic and necrotic blisters was eventually diagnosed as being the victim of probable spider bites. Arachnidism, specifically loxoscelism (brown recluse spider bite), is unusual in the northeastern United States.