Viperid venom glands with defective venom production. Morphological study.

The venom of viperid snakes is collected monthly at Butantan Institute for research purposes and production of antivenoms. Here we describe histological and ultrastructural changes on Crotalus durissus terrificus and Bothrops sp. venom glands with defective venom production. Secretory tubules commonly showed partial or total obliteration of their lumina by masses of necrotic cells and cellular debris. Secretory cells showed varying degrees of degenerative and/or metaplastic alterations seriously affecting the structures responsible for the synthesis and secretion of venom. The intertubular connective tissue presented fibroblast hyperplasia, inflammatory cells infiltration, vacuolated cells and blood vessels alterations. In two venom glands out of nineteen snakes examined, virus-like particles were found. The alterations observed in most of the glands could have been caused by excessive manual pressure, during venom extraction routine, causing disruption of the secretory tubules and leakage of venom to the intertubular connective tissue.

Avaliação do efeito do inseticida malathion aplicado sob a forma de ultra baixo volume com equipamentos portátil e pesado sobre Aedes aegypti (Diptera: Culicidae) / Evaluation of the efect of insecticide Malathion applied as ultra low volume with portable and vehicle-mounted machines on Aedes aegypti control

Avaliou-se o efeito da aplicação de inseticida sobre formas adultas de Aedes aegypti realizada a ultrabaixo volume (UBV) com atomizadores motorizados portáteis e acoplados a veículo. Os tratamentos com ambos os equipamentos foram realizados em São José do Rio Preto e Marília, estado de São Paulo, Brasil. A efetividade foi verificada pela exposição de fêmeas de Ae. aegypti em gaiolas-sentinela. O impacto das aplicações na população adulta do vetor foi avaliado por meio dacoleta de adultos no intradomicílio e peridomicílio antes e após os tratamentos. Os resultados obtidoscom cada equipamento foram semelhantes nas duas cidades. A mortalidade de fêmeas expostas emgaiolas-sentinela, no intradomicílio, atingiu percentual médio de 96,5por cento nas duas cidades nas áreastratadas com equipamento portátil. Foi de 54,3por cento o percentual nas áreas tratadas com equipamento acoplado a veículo. Na avaliação de impacto sobre a população adulta, as coletas revelaram que o equipamento portátil causou redução média de 84,3por cento na positividade dos imóveis e 77,9por cento de diminuição no número de fêmeas por imóvel. Com equipamento acoplado a veículo, houve reduçãode 49,7por cento na positividade de imóveis para fêmeas de Ae. aegypti e de 44,6por cento no número de fêmeaspor imóvel. Os resultados demonstraram impacto significativamente maior na população adulta com equipamento portátil e também maior mortalidade no intradomicílio, local de maior permanência das fêmeas do vetor.

Observations on Haemagogus janthinomys Dyar (Diptera: Culicidae) and other mosquito populations within tree holes in a gallery forest in the northwestern region of Sao Paulo state, Brazil.

In 2000, an outbreak of sylvatic yellow fever possibly occurred in gallery forests of the Grande river in the Paraná basin in the northwestern region of São Paulo state. The aim of this study was to obtain information on the bionomics of Haemagogus and other mosquitoes inside tree holes in that area. Eighteen open tree holes were sampled for immature specimens. Adults were collected twice a month in the forest in Santa Albertina county from July 2000 to June 2001. The seasonal frequency of fourth instars was obtained by the Williams geometric mean (Mw), while the adult frequency was estimated either by hourly arithmetic or the Williams' means. Cole's index was applied to evaluate larval inter-specific associations. Among the ten mosquito species identified, the most abundant was Aedes terrens Walker followed by Sabethes tridentatus Cerqueira and Haemagogus janthinomys Dyar. Larval and adult abundance of these species was higher in summer than in winter. Although larval abundance of Hg. janthinomys peaked in the rainy season, correlation with rainfall was not significant. Six groups of larval associations were distinguished, one of which the most positively stable. The Hg. janthinomys and Ae. terrens association was significant, and Limatus durhamii Theobald was the species with most negative associations.

Entomological investigation of a sylvatic yellow fever area in São Paulo State, Brazil

O registro de dois casos autóctones de febre amarela silvestre no Estado de São Paulo, Brasil, em 2000, desencadeou investigações entomológicas com o objetivo de verificar a ocorrência das espécies vetoras em ambientes florestais próximos ou associados às zonas ribeirinhas, situados nas regiões oeste e noroeste do Estado. As capturas foram realizadas em 39 localidades distribuídas por quatro regiões do Estado. Haemagogus leucocelaenus e Aedes albopictus foram as espécies mais abundantes e capturadas em todas as regiões. H. leucocelaenus foi a espécie mais abundante nos municípios de Santa Albertina e Ouroeste, onde os casos de febre amarela silvestre foram registrados. Mosquitos do grupo janthinomys/capricornii foram encontrados em oito localidades de São José do Rio Preto, enquanto Sabethes chloropterus uma única vez em localidade de Ribeirão Preto. Ficou evidenciada a aptidão de H. leucocelaenus para adaptar-se a ambiente secundário e degradado. Nossos resultados apontam para uma ampla área receptiva para a transmissão de febre amarela, com destaque para a possibilidade de H. leucocelaenus estar envolvido na manutenção deste foco silvestre da doença.

Entomological investigation of a sylvatic yellow fever area in São Paulo State, Brazil.

Following reports of two autochthonous cases of sylvatic yellow fever in the State of São Paulo, Brazil, in 2000, entomological surveys were conducted with the objective of verifying the occurrence of vector species in forest environments close to or associated with riparian areas located in the western and northwestern regions of the State. Culicidae were captured in 39 sites distributed in four regions. Haemagogus leucocelaenus and Aedes albopictus were the most abundant species and were captured in all the regions studied. H. leucocelaenus was the most abundant species in the municipalities of Santa Albertina and Ouroeste, where the two cases of sylvatic yellow fever had been reported. Mosquitoes from the janthinomys/capricornii group were only found at eight sites in the São José do Rio Preto region, while Sabethes chloropterus was found at one site in Ribeirão Preto. H. leucocelaenus showed its capacity to adapt to a secondary and degraded environment. Our results indicate a wide receptive area for yellow fever transmission in the State of São Paulo, with particular emphasis on the possibility of H. leucocelaenus being involved in the maintenance of this sylvatic focus of the disease.

Studies on entomological monitoring: mosquito species frequency in riverine habitats of the Igarapava Dam, Southern Region, Brazil.

Diversity of mosquito species was evaluated in different habitats before and after the Igarapava reservoir flooding in the Grande River, Southern Cerrado of Brazil. We aimed at verifying changes in these mosquito populations in consequence of the lake formation. Four habitats were selected as sampling stations: peridomiciliary habitat, pasture, "veredas" and gallery forest patch. Bimonthly collections were made with the Shannon trap and human bait, including diurnal, crepuscular and nocturnal period of mosquito activity. The Shannon Index results from the potential vectors were compared using Student t-test. Aedes scapularis, Anopheles darlingi and An. albitarsis senso latu seasonal abundance were described with moving average and compared using chi2 test. There were changes in the mosquito frequency in the habitats, except for the "veredas" that was 13 km away from the catchment area. The altering in mosquito species seasonal abundance suggests breeding places expansion. Diversity indexes can be used to monitor changes in mosquito vector population in environments where abrupt disturbance can alter disease transmission cycles.

[Dengue vector control and community participation in Catanduva, São Paulo State, Brazil]. / Controle do vetor do dengue e participação da comunidade em Catanduva, São Paulo, Brasil.

This study aimed to identify changes in knowledge and practices learned to prevent dengue fever in two areas of Catanduva, São Paulo State, from 1999 to 2001: a study area and a control area. The study included an initial quantitative survey, qualitative research, a preliminary diagnosis presented to the community to launch a discussion aimed at defining future actions, implementation of the actions in the study area with community participation (but without changes in the control area), and a final comparison of the two areas. Changes in the study area included: vector control workers began demonstrating preventive measures without removing potential breeding places or using larvicide; use of educational aids specific to the local reality; activities related to the residents priorities; and activities such as music, theater skits, scavenger hunts, and games to demonstrate the vector cycle. Potential domiciliary breeding sites were significantly reduced; the proportion of houses without breeding sites was significantly increased; and there was an increase in the percentage of individuals who recognized the larval form of the vector in the study area as compared to the control area.