BackgroundIn Brazil, dengue epidemics erupt sporadically throughout the country and it is unclear if outbreaks may initiate a sustainable transmission cycle. There are few studies evaluating the ability of Brazilian Aedes aegypti populations to transmit dengue virus (DENV). The aim of this study was to compare DENV susceptibility of field-captured Ae. aegypti populations from nine distinct geographic areas of the city of Belo Horizonte in 2009 and 2011. Infection Rate (IR), Vector Competence (VC) and Disseminated Infection Rate (DIR) were determined.MethodsAedes aegypti eggs from each region were collected and reared separately in an insectary. Adult females were experimentally infected with DENV-2 and the virus was detected by qPCR in body and head samples. Data were analyzed with the Statistical Package for the Social Sciences version 17.ResultsIR varied from 40.0% to 82.5% in 2009 and 60.0% to 100.0% in 2011. VC ranged from 25.0% to 77.5% in 2009 and 25.0% to 80.0% in 2011. DIR oscillated from 68.7% to 100.0% in 2009 and 38.4% to 86.8 in 2011. When the results were evaluated by a logistic model using IR as covariate, North, Barreiro, South-Central and Venda Nova showed the strongest association in 2009. In 2011, a similar association was observed for South-Central, Venda Nova, West and Northeast regions. Using VC as covariate, South-Central and Venda Nova showed the most relevant association in 2009. In 2011, South-Central, Venda Nova and Barreiro presented the greatest revelation associations. When DIR data were analyzed by logistic regression models, Pampulha, South-Central, Venda Nova, West, Northeast and East (2009) as well as South-Central, Venda Nova and West (2011) were the districts showing the strongest associations.ConclusionsWe conclude that Ae. aegypti populations from Belo Horizonte exhibit wide variation in vector competence to transmit dengue. Therefore, vector control strategies should be adapted to the available data for each region. Further analysis should be conducted to better understand the reasons for this large variability in vector competence and how these parameters correlate with epidemiological findings in subsequent years.

The geographic information system approach has permitted integration between demographic, socio-economic and environmental data, providing In the 1990s, an increasing capacity of data analysis and ease of information accessibility through cheap and simple computational systems was remarkable. Such technology represents a breakthrough in data bank organization, mainly regarding health.Geoprocessing is a broad term that is applied to several technologies of manipulation and processing of geographical data through computational programs. System of geographical information (SGI) is one of the geoprocessing techniques, the most widely used, once it gathers organized data at the stages of data capture by remote sensing, GPS or organization of digital cartographic basis, and organizes systems, which are able to obtain new information and improve knowledge. SGI comprises computational systems used for understanding facts and phenomena that occur in the geographical space. Its capacity of gathering data sets of conventional spatial expression, structuring and integrating them adequately, makes it an essential tool for manipulating geographical information (Pina 1994).Applications of SGI in the field of health have been reported in studies on epidemiological surveys, health service assessment, urbanization, and environment. Moreover, evaluation of endemic diseases from the perspective of several elements involved in the transmission cycle, such as historical, environmental, and social determinants of disease foci, became easier with Geoprocessing techniques (Sabroza et al. 1992, Albuquerque 1993, Thomson & Connor 2000.Geoprocessing technology has enabled scientists to map vectors and analyze environmental factors that affect spatial and temporal distribution of insects. Such techniques have been used to monitor diseases such as malaria, trypanosomiasis, and leishmaniases (Elnaiem et al. 1998, Thomson & Connor 2000.American cutaneous leishmaniasis (ACL) and visceral leishmaniasis (VL) have been studied through geoprocessing techniques by several investigators: Cross et al. (1996), by gathering data from 136 scientific papers, have generated a distribution model of Phlebotomus papatasi in Southeast Asia throughout the year. By using satellite images and field-collected data in Sudan, Elnaiem et al. (1998Elnaiem et al. ( , 2003 and Thomson et al. (1999) observed that several ecological factors are crucial for the presence of Phlebotomus orientalis, the vector of VL in that country. Kawa and Sabroza (2002) and Werneck and Maguire (2002) have analyzed historical and spatial determinants, in the city of Rio de Janeiro, Brazil, and Teresina, state of Piauí, Brazil, respectively, for implementation, maintenance, and spread of ACL and their correlation with urban organization and occupation in the periphery of those cities. Hay et al. (1997), Connor et al. (1998), andKing et al. (2004) Therefore, data collection through geoprocessing techniques has contributed to monitor and specially to identify effective and priority contro...

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Between October, 1997 and September, 1999 in Belo Horizonte, Minas Gerais a study of seasonal variation of Lutzomyia longipalpis was carried out in three distinct areas of the municipality. Sand flies were sampled at 15-day intervals in three residences, in each of which two CDC light traps were installed, one indoors and the other in the peridomicile. A total of 397 sand flies were captured in the three areas, with 65%, 30% and 1% of specimens collected in the eastern, northeast and Barreiro districts, respectively. The overall proportions of sand flies collected inside and around the houses were similar (57% vs 43%) and this pattern was seen for both Lutzomyia longipalpis and Lutzomyia whitmani. The highest population levels during the two years of the study were from October to March. From October onwards, numbers increased constantly until February. A gradual fall was seen from April onwards until the lowest levels were reached in the months of June, July and August. Key-words: Sand fly. Seasonal variation. Control. Leishmaniasis. RESUMOEntre outubro de 1997 e setembro de 1999, em Belo Horizonte, Minas Gerais foi conduzido um estudo de variação sazonal de Lutzomyia longipalpis em três áreas distintas do município. Os flebotomíneos foram coletados quinzenalmente em três residências, em cada área, nas quais foram instaladas duas armadilhas luminosas CDC, sendo uma no intradomicílio e a outra no peridomicílio. Um total de 397 flebotomíneos foi capturado nas três áreas, com 65%, 30% e 1% exemplares coletados nos distritos Leste, Nordeste e Barreiro, respectivamente. A proporção total de flebotomíneos coletados no intradomicílio e peridomicílio foi semelhante (57% vs 43%) e este padrão foi visto para Lutzomyia longipalpis e Lutzomyia whitmani. Durante os dois anos de estudo, o nível da população foi maior no período de outubro a março. A partir de outubro o número de flebotomíneos aumenta constantemente até fevereiro. Uma gradual redução foi observada a partir de abril até alcançar o nível mais baixo nos meses de junho, julho e agosto. Palavras-chaves: Flebotomíneos. Variação sazonal. Controle. Leishmanioses.

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According to our results it can be suggested that lateral flow tests for NS1 detection are the most feasible methods for early diagnosis of dengue.

About 97% of the human cases of the American visceral leishmaniasis (VL) occur in Brazil. In the last few years, the disease expanded to medium- and large-sized cities, in which surveillance and control actions have been intensified, in an effort to control VL spreading. Our two-year study was conducted in Belo Horizonte, the sixth most populous city in Brazil, which is endemic for VL. We focused in two particular districts of recent transmission of the disease, with no reported human cases and submitted to minor surveillance and control actions. Our aim was to draw an epidemiological profile of the local situation concerning Lutzomyia vector, Leishmania parasites, and the main domestic reservoirs (dogs). Lutzomyia longipalpis comprised 96.5% of the total phlebotomine sand flies captured and displayed an expressive minimal infection rate by Leishmania infantum (16.7%). Positive correlations were found between the population densities of L. longipalpis, rainfall and temperature. L. infantum was also detected in the cortelezzii complex and, for the first time, in Lutzomyia lloydi. Leishmania braziliensis, an etiological agent of the American cutaneous leishmaniasis, was also identified in L. longipalpis. Among the 1408 dogs serologically tested by standard enzyme-linked and fluorescence immune assays (ELISA/IFA) 3.6% were positive for VL. L. infantum DNA and Leishmania parasites were identified in 100% and 72.5% of the seropositive dogs, respectively. The co-positivity of other diagnostic tests for VL-Leishmania-nested PCR, imprint and myeloculture-was compared to the standard serology. Both symptomatic or asymptomatic dogs displayed an equal average number of positive diagnostic tests for VL. The districts studied display favorable conditions for the rapid spreading of human infection, in terms of L. longipalpis population density, and presence of L. infantum in both vector and main reservoir.

In this study, seroprevalence was lower than in previous studies carried out in mid-size and large Brazilian cities. This suggests that Belo Horizonte has employed efficient control measures. However, heterogeneity within the city was observed in terms of dengue fever transmission, which was largely associated with contextual indicators of vulnerability. The number of susceptibles is still high, and the control of dengue fever remains a difficult public health issue.