Sugestão de Leitura

Abstract: Este artigo apresenta um meio de suporte à decisão para, dada uma tolerância de distância total e/ou máxima entre focos da doença e facilidades, determinar o número mínimo de facilidades a serem instaladas, o que representa um melhor uso da verba pública com um melhor atendimento à população.

Abstract: Roraima is the northernmost state of Brazil, bordering both Venezuela and Guyana. Appropriate climate and vector conditions for dengue transmission together with its proximity to countries where all four dengue serotypes circulate make this state, particularly the capital Boa Vista, strategically important for dengue surveillance in Brazil. Nonetheless, few studies have addressed the population dynamics of Aedes aegypti in Boa Vista. In this study, we report temporal and spatial variations in Ae. aegypti population density using ovitraps in two highly populated neighbourhoods; Centro and Tancredo Neves. In three out of six surveys, Ae. aegypti was present in more than 80% of the sites visited. High presence levels of this mosquito suggest ubiquitous human exposure to the vector, at least during part of the year. The highest infestation rates occurred during the peak of the rainy seasons, but a large presence was also observed during the early dry season (although with more variation among years). Spatial distribution of positive houses changed from a sparse and local pattern to a very dense pattern during the dry-wet season transition. These results suggest that the risk of dengue transmission and the potential for the new serotype invasions are high for most of the year.

Abstract: Recentemente, a dinâmica populacional e dispersão do mosquito vetor do vírus Dengue, o Aedes aegypti, tem sido objeto de vários estudos. O uso de modelos computacionais para simulação dessa dinâmica é de grande importância para Saúde Pública, uma vez que permite avaliar áreas de risco de transmissão do Dengue. O Rio de Janeiro, RJ, tem enfrentado fortes epidemias de dengue, sendo a mais grave em 2008. Com o objetivo de entender a ecologia do Aedes aegypti, este trabalho propõe um novo modelo espacialmente-explícito para simular a dinâmica populacional desse vetor no bairro de Higienópolis. O modelo considera a influência de variáveis climáticas e ambientais e permite a construção de estimativas a respeito da quantidade mínima de criadouros existentes na região de estudo suficiente para sustentar a taxa de oviposição amostrada ao longo do tempo (número de ovos/semana). Foram utilizadas amostras semanais de medidas de oviposição para alguns setores censitários do bairro, coletadas no período de setembro de 2006 a março de 2008 por equipes da Fundação Oswaldo Cruz (FIOCRUZ). Medidas semanais de temperatura foram coletadas a partir da Estação Meteorológica do Galeão, Rio de Janeiro, RJ. O modelo desenvolvido foi integrado ao banco de dados geográficos também desenvolvido neste trabalho, de forma a permitir seu uso para a identificação de locais de maior concentração de criadouros e, assim, direcionar ações de controle. O modelo desenvolvido tem suas bases no modelo confeccionado por Ferreira e Yang (2003) e em algumas melhorias propostas por Otero et al. (2006). Outras melhorias são contribuições originais deste esforço como a determinação de uma relação quadrática entre a estatística de oviposição e a temperatura ambiente, o modelo para inibição da oviposição pela excessiva densidade de larvas, e a metodologia para estimação da densidade de criadouros a partir de medidas de oviposição. O modelo proposto foi implementado no ambiente de modelagem TerraME, posteriormente, calibrado e validado para o bairro de Higienópolis, Rio de Janeiro, RJ.

Abstract: During the month of June 2009, Mauritius experienced a short-lived outbreak of dengue fever localised in its capital city Port Louis. Aedes albopictus, a secondary vector of dengue viruses, was the probable vector. We introduce a method which combines Google Earth images, stochastic cellular automata and scale free network ideas to map this outbreak. The method could complement other techniques to forecast the evolution of potential localised mosquito-borne viral outbreaks in Mauritius and in at-risk locations elsewhere for public health planning purposes.

Abstract: Aedes aegypti is a very efficient disseminator of human pathogens. This condition is the result of evolutionary adaptations to frequent haematophagy, as well as to the colonization of countless types of habitats associated with environmental and cultural factors that favor the proliferation of this mosquito in urban ecosystems. Studies using sensitive methods of monitoring demonstrate that the methods of surveillance used in the Brazilian program do not show the high degrees of the infestation of cities by this vector. To increase the capacity of the health sector, new tools are needed to the practice of surveillance, which incorporate aspects of the vector, place and human population. We describe here the SMCP-Aedes – Monitoring System and Population Control of Aedes aegypti, aiming to provide an entomological surveillance framework as a basis for epidemiological surveillance of dengue. The SMCP-Aedes is uphold in the space technology information, supported by the intensive use of the web and free software to collect, store, analyze and disseminate information on the spatial-temporal distribution of the estimated density for the population of Aedes, based on data systematically collected with the use of ovitraps. Planned control interventions, intensified where and when indicated by the entomological surveillance, are agreed with the communities, relying on the permanent social mobilization.

Abstract: A periodically forced two-dimensional cellular automata model is used to reproduce and analyze the complex spatiotemporal patterns observed in the transmission of vector infectious diseases. The system, which comprises three population levels, is introduced to describe complex features of the dynamics of the vector-transmitted dengue epidemics, known to be very sensitive to seasonal variables. The three coupled levels represent the human, the adult, and immature vector populations. The dynamics includes external seasonality forcing, human and mosquito mobility, and vector control effects. The model parameters, even if bounded to well-defined intervals obtained from reported data, can be selected to reproduce specific epidemic outbursts. In the current study, explicit results are obtained by comparison with actual data retrieved from the time series of dengue epidemics in two cities in Brazil. The results show fluctuations that are not captured by mean-field models. It also reveals the qualitative behavior of the spatiotemporal patterns of the epidemics. In the extreme situation of the absence of external periodic drive, the model predicts a completely distinct long-time evolution. The model is robust in the sense that it is able to reproduce the time series of dengue epidemics of different cities, provided that the forcing term takes into account the local rainfall modulation. Finally, an analysis is provided of the effect of the dependence between epidemics threshold and vector control actions, both in the presence and absence of human mobility factor.

Abstract: The efficacy of biological control of Aedes aegypti mosquitoes using Sterile Insect Technique (SIT) is analyzed. This approach has shown to be very efficient on agricultural plagues and has become an alternative control strategy to the usual technique of insecticide application, which promotes resistance against chemical controls and is harmful to other species that live in the same mosquito habitat. By using a discrete cellular automata approach we have shown that in the case of Aedes aegypti, the spatially heterogeneous distribution of oviposition containers and the mosquito behavior, especially with respect to mating, make the application of STI difficult or impracticable.

Abstract: A new approach to dengue vector surveillance based on permanent egg-collection using a modified ovitrap and Bacillus thuringiensis israelensis (Bti) was evaluated in different urban landscapes in Recife, Northeast Brazil. From April 2004 to April 2005, 13 egg-collection cycles of four weeks were carried out. Geo-referenced ovitraps containing grass infusion, Bti and three paddles were placed at fixed sampling stations distributed over five selected sites. Continuous egg-collections yielded more than four million eggs laid into 464 sentinel-ovitraps over one year. The overall positive ovitrap index was 98.5% (over 5,616 trap observations). The egg density index ranged from 100 to 2,500 eggs per trap-cycle, indicating a wide spread and high density of Aedes aegypti (Diptera: Culicidae) breeding populations in all sites. Fluctuations in population density over time were observed, particularly a marked increase from January on, or later, according to site. Massive egg-collection carried out at one of the sites prevented such a population outbreak. At intra-site level, egg counts made it possible to identify spots where the vector population is consistently concentrated over the time, pinpointing areas that should be considered high priority for control activities. The results indicate that these could be promising strategies for detecting and preventing Ae. aegypti population outbreaks.

Abstract: Neste trabalho desenvolvelmos um modelo dinâmico espaço-temporal baseado em autômatos celulares estocásticos para simular a dinâmica de transmissão da dengue em uma comunidade densa. É um modelo que acopla as dinâmicas de humanos e mosquitos. Indivíduos e vetores são monitorados individualmente. Mosquitos vivem em residências específicas e fazem repasto sanguíneo de acordo com certa distribuição espacial. A população humana não é estruturada por idade. A mobilidade humana é levada em consideração e determina a época central e aduração da epidemia. O modelo é utilizado para estudar três questões relativas à dinâmica da dengue. A primeira é a sensibilidade da reprodutibilidade da infecção a diferentes parâmetros. A segunda é a viabilidade da transmissão viral durante períodos interepidêmicos. Uma análise de metapopulações é feita para estimar a probabilidade do vírus se extinguir em um grande centro urbano. A terceira é a hipótese da imunidade cruzada para diferentes sorotipos, considerando a entrada de dois sorotipos, inclusive simultaneamente.

Abstract: The susceptible-infected-susceptible (SIS) epidemics in a scale-free network in which each node is a square lattice itself is investigated through large-scale computer simulations. The model combines a local contact process among individuals in a node (or city) with stochastic long-range infections due to people traveling between cities interconnected by the national transportation scale-free network. A nonzero epidemic threshold is found and it is approached with a power-law behavior by the density of infected individuals, as observed in the small-world network of Watts and Strogatz. Also, the epidemic propagation follows a 1=f , hierarchical dynamics from the highly connected square lattices to the smaller degree nodes in outbreaks with sizes distributed accordingly a Gaussian function.