This study presents the epidemiological analysis of 20,699 reported spider bites involving the Loxosceles genus in the state of Paraná, Brazil, from 1993 to 2000. The incidence rate in the period was 290.24/100,000 inhabitants. The results show that 95.04% of the accidents occurred in two Health Regions of the state: greater metropolitan Curitiba (92.9%) and Irati (2.14%). The major incidence was recorded in greater metropolitan Curitiba (559.1/100,000). Loxosceles bites were more frequent in females (61%) than in males. Antivenin therapy was not necessary in 95.4% (19,662) of the cases. From the cases in which information about the time elapsed between the bite and medical treatment was recorded (9,679), 31.8% received treatment from 6 to 48 hours after the bite. Among the cases with severity rate recorded (12,096), 2.1% were severe, 50.4% moderate, and 47.4% mild. Seven deaths from Loxosceles bites were recorded, corresponding to a fatality rate of 0.03%.

Bites from the recluse or brown spiders (genus Loxosceles) can cause necrotic lesions and systemic effects in humans throughout the world. In the state of Paraná, Brazil, loxoscelism is considered a serious public health problem, and Loxosceles intermedia Mello-Leitão (Araneae: Sicariidae) is associated with the majority of reported accidents. In the present research we evaluated the susceptibility of L. intermedia to pyrethroid insecticides currently used for the control of spiders in both field and laboratory conditions. In laboratory tests, the most active pesticides in descending order were microencapsulated lambda-cyhalothrin (LC50 = 0.023 mg/kg), nonmicroencapsulated lambda-cyhalothrin (LC50 = 0.047 mg/kg), deltamethrin (LC50 = 0.26 mg/kg), and cypermethrin (LC50 = 1.38 mg/kg). Cockroaches, Phoetalia circumvagans (Burmeister) (n = 30), killed with microencapsulated lambdacyalothrin, were offered to the spiders. L. intermedia fed on 63.3% of the dead cockroaches during the first 6 h of experiment; none of the spiders died during the subsequent 15 d. Microencapsulated lambdacyalothrin was chosen for application in two contiguous houses. The mean volume applied was 22.8 mg (AI)/m2. Dead spiders were found during all the inspections up to 60 d after the initial application. In total, 297 dead spiders were collected; 65.7% in the attic shared by the two homes, 10.8% inside the house that had most cracks and crevices sealed and 23.6% in the control house. The use of lambda-cyhalothrin-based products for L. intermedia control is discussed.

ABSTRACT. The frequency of jellyfish blooms is generating a world-wide discussion about medusae population explosions, mainly those associated with stings. We report over 20,000 envenomations caused by Chrysaora lactea (Scyphozoa) in the State of Paraná (southern Brazil) during the austral summer of 2011-2012. Envenomations were considered mild, but almost 600 cases were treated in emergency services, with either toxic and allergic reactions, some with systemic manifestations. We proposed non-exclusive hypotheses to explain this large number of cases. Keywords: Chrysaora lactea, Scyphozoa, jellyfish, envenomation, public health, stings, Paraná, Brazil.Agregaciones de medusas (Chrysaora lactea, Cnidaria, Semaeostomeae) en el sur de Brasil y consecuencias de picaduras en humanos RESUMEN. La frecuencia de 'blooms' de medusas está generando debate a nivel mundial sobre los incrementos de poblaciones de medusas, sobre todo lo relacionado con picaduras. Se reportan más de 20.000 envenenamientos ocasionados por Chrysaora lactea (Scyphozoa) en el Estado de Paraná (sur del Brasil) durante el verano austral 2011-2012. Los envenenamientos fueron considerados leves, pero cerca de 600 casos fueron tratados en los servicios de emergencia, ya sea con reacciones toxicas o alérgicas, algunas de ellas con manifestaciones sistémicas. Se proponen hipótesis no excluyentes para explicar este gran número de casos.

Some venomous spiders of the genus Loxosceles can reach high population densities inside and around houses. In Brazil, most spider accidents are related to Loxosceles intermedia. Control of loxoscelism should utilize integrated pest management tools, such as vacuum cleaners, to eliminate egg sacs, webs and spiders. The present study tested the efficacy of one type of vacuum cleaner (for professional and domestic use) in the control of L. intermedia populations. Cockroaches (Pycnoscelus surinamensis) were used in some tests for comparison. Vacuuming using standard accessories or a paper tube resulted in the death of all female (n=60), male (n=60), young (n=60) and just-hatched (n=60) L. intermedia, and all egg sacs (n=5) were destroyed. The removal of the plastic plate present at the bottom of the vacuuming tube inside the machine allowed some spiders to survive the vacuuming process. When kept inside a vacuum bag full of dust and debris, adult females (n=10) survived for 10 days; however, significant mortality was observed among male (n=10) and young individuals (n=10). Addition of cornstarch to the vacuum bag did not affect the spiders (n=20). Vacuum cleaners, such as the one used in the present investigation, are promising tools for integrated management of L. intermedia and other spiders in domestic environments

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