Marina Atanaka-Santos

Spatial analysis for stratification of priority malaria control areas, Mato Grosso State, Brazil

The goal of this study was to stratify priority areas for malaria control in the State of Mato Grosso, Brazil, based on spatial analysis. The variables used were: Annual Parasite Index (API), Plasmodium falciparum/Plasmodium vivax ratio, population variation, number of families settled, and percent of deforested area. The Morans I and Local Moran Test were applied, visualized with the Box Map and Moran Map, for 1986- 1991, 1992-1997, and 1998-2003. Box Map identified areas with high, low, and intermediate priority for control, and Moran Map identified municipalities with significant autocorrelation. In the high priority area, located in the North of Mato Grosso, malaria incidence decreased drastically despite the increase in the number of municipalities from the first to the last period. Other municipalities were added to the lower priority area, from the Southeast, Southwest, and Central-South of the State. The intermediate priority area was located along the border with neighboring States and municipalities classified as high and low priority. Spatial analysis showed the importance of the neighboring phenomenon between municipalities in defining priority areas, thus highlighting the techniques advantages for use in malaria control and surveillance.

Geographic information systems and logistic regression for high-resolution malaria risk mapping in a rural settlement of the southern Brazilian Amazon

BackgroundIn Brazil, 99% of the cases of malaria are concentrated in the Amazon region, with high level of transmission. The objectives of the study were to use geographic information systems (GIS) analysis and logistic regression as a tool to identify and analyse the relative likelihood and its socio-environmental determinants of malaria infection in the Vale do Amanhecer rural settlement, Brazil.MethodsA GIS database of georeferenced malaria cases, recorded in 2005, and multiple explanatory data layers was built, based on a multispectral Landsat 5 TM image, digital map of the settlement blocks and a SRTM digital elevation model. Satellite imagery was used to map the spatial patterns of land use and cover (LUC) and to derive spectral indices of vegetation density (NDVI) and soil/vegetation humidity (VSHI). An Euclidian distance operator was applied to measure proximity of domiciles to potential mosquito breeding habitats and gold mining areas. The malaria risk model was generated by multiple logistic regression, in which environmental factors were considered as independent variables and the number of cases, binarized by a threshold value was the dependent variable.ResultsOut of a total of 336 cases of malaria, 133 positive slides were from inhabitants at Road 08, which corresponds to 37.60% of the notifications. The southern region of the settlement presented 276 cases and a greater number of domiciles in which more than ten cases/home were notified. From these, 102 (30.36%) cases were caused by Plasmodium falciparum and 174 (51.79%) cases by Plasmodium vivax. Malaria risk is the highest in the south of the settlement, associated with proximity to gold mining sites, intense land use, high levels of soil/vegetation humidity and low vegetation density.ConclusionsMid-resolution, remote sensing data and GIS-derived distance measures can be successfully combined with digital maps of the housing location of (non-) infected inhabitants to predict relative likelihood of disease infection through the analysis by logistic regression. Obtained findings on the relation between malaria cases and environmental factors should be applied in the future for land use planning in rural settlements in the Southern Amazon to minimize risks of disease transmission.

Comportamento epidemiológico da malária no Estado de Mato Grosso, 1980-2003

The temporal and spatial evolution of malaria in Mato Grosso was determined in periods from 1980-1985, 1986-1991, 1992-1997 and 1998-2003 and distributed by homogeneous microregion. The annual parasitic index of the state rose until 1992 and then diminished to 1.9 cases/1,000 inhabitants in 2003, the ratio of mortality and the lethality rate were greater in the 1980s. Of the 22 microregions, 13 presented an API inferior to 10 cases/1,000 inhabitants in all periods. Cases were concentrated in the microregions of Colíder, Alta Floresta, Aripuanã and Alto Guaporé. In 2003, only the microregion of Aripuanã continued to present an API superior to 50 cases/1,000 inhabitants. The microregions of Colíder, in 1983, 1985 to 1988 and 1990 and Alta Floresta, in 1991 presented deaths over 50/100,000 inhabitants, mainly in males aged 20-49 years. The distribution of the disease in microregions showed that malaria is predominantly found in concentrated sites.

Malformações congênitas em municípios de grande utilização de agrotóxicos em Mato Grosso, Brasil

Mato Grosso e o maior produtor agricola e tambem o maior consumidor nacional de agrotoxicos. A exposicao materna aos agrotoxicos no periodo periconcepcional tem sido associada com aumento no risco de malformacoes congenitas. O objetivo deste artigo e analisar a associacao entre o uso de agrotoxicos e as malformacoes congenitas em municipios com maior exposicao aos agrotoxicos em Mato Grosso. Estudo de caso-controle realizado com 219 nascidos vivos com malformacao congenita e 862 nascidos vivos sadios. Estimou-se a media de utilizacao dos agrotoxicos nos trimestres anterior e posterior a data da fecundacao e durante todo o periodo periconcepecional segundo municipio e mes e ano de sua utilizacao. Posteriormente, estas medidas foram quartilizadas e transformadas em variaveis do tipo indicadoras (dummy ), atribuindo-se um nivel de exposicao para cada intervalo interquartil. Foi realizada analise bivariada e regressao logistica. Foram observadas associacoes significantes (p < 0,05) no terceiro (OR=1,66, IC95% 0,98 - 2,79) e quarto quartil (OR=1,88, IC95% 1,09 - 3,24) do periodo pos-fecundacao e no quarto quartil (OR=2,04, IC95%1,17-3,56) durante todo o periodo periconcepecional. A exposicao materna aos agrotoxicos foi associada a maior ocorrencia de malformacoes congenitas.

Fatores socioambientais associados à distribuição espacial de malária no assentamento Vale do Amanhecer, Município de Juruena, Estado de Mato Grosso, 2005

Malaria is a disease with focal distribution. In Brazil, settlement and gold mining areas in the Legal Amazon region present a great concentration of cases. This paper analyzes the spatial distribution of malaria cases taking into consideration environmental and social factors in the Vale do Amanhecer settlement in the municipality of Juruena, Mato Grosso, Brazil. In 2005, 359 autochthonous cases were notified in the settlement. Using the Kernel method, areas of greater and lesser intensities of case numbers were identified. The areas of greater intensity presented 290 cases and those of lesser intensity, 64 cases. The intensity of distribution varied within the settlement, thus indicating areas of great intensity of cases favoring transmission, like gold mining areas. Therefore, although the settlement was considered to be the main focus for malaria, there were specific factors within it that, once identified, could contribute towards the disease control.

Factors associated with the incidence of malaria in settlement areas in the district of Juruena, Mato Grosso state, Brazil

Factors associated with the incidence of malaria in the Vale do Amanhecer settlement, Juruena, Mato Grosso in 2005 were analyzed. Two hundred settlers of both genders and aged 18 years and above were interviewed. The prevalence of malaria reported in 2005 was 33%. The prevalence ratio showed that the highest prevalence of malaria was found in individuals involved in gold mining activities (67%); who came from non-endemic areas (43%); had inadequate knowledge about the time of greatest activity of the vector (71%); and who reported being outside after 5 p.m. (59%). It was concluded that in the Vale do Amanhecer settlement, factors such as occupation, origin, inadequate knowledge about where malaria is transmitted, inadequate knowledge about the time the mosquito usually bites and individual practices in relation to the peak period of mosquito activity were associated with malaria in 2005.

Prioridades da pesquisa em epidemiologia na região do Pantanal brasileiro

The Brazilian Pantanal (or “Wetland” in Portuguese) is located in the center of South America, in the Upper Paraguay River Basin. The area measures a total of 150,355 square kilometers, making it the world’s largest wetland. The Pantanal is located in southern Mato Grosso and northwestern Mato Grosso do Sul State. According to the 2010 Census, the population was 400 thousand, having grown 9.3% in the previous decade. The Pantanal biome displays wide biological diversity resulting from its multiple and complex interdependent interactions. Together with physical biodiversity, the Pantanal is demographically unique, as home to the pantaneiros, indigenous peoples, communities along the border with Bolivia and Paraguay, and people from other Latin American countries that have come in search of opportunities, besides tourists from all over the world. Interpersonal and intercultural interactions, mediated by the region’s hydrological and economic cycle, shape specific ways of life and health conditions, thereby creating research opportunities and demands in epidemiology. Within this scenario there is a striking lack of research on health conditions, especially the dynamics in the maintenance and potential occurrence of diseases arising from contact with environments that can present vulnerabilities and harbor reservoirs for diseases (particularly vector-borne). Research is needed on the local receptiveness and impact of migratory birds from other regions of the world, potential carriers of new infectious agents such as the West Nile virus. The region’s low altitude (an average of 100 meters above sea level) and the surrounding higher lands, with altitudes of 600 to 700 meters, expose the Pantanal population to environmental contaminants such as crop pesticides used extensively by agribusiness, the magnitude and impact of which need to be studied. Equally important is the evaluation of the environmental impact and harmful potential for human health resulting from largescale sugar cane plantations. Even while pesticides have emerged as a problem in recent decades, there is a persistent risk of waterborne diseases due to the water consumed by the Pantanal’s rural populations, exposed to periodic floods, unlike other rural populations. The long international border area and the ease in acquiring legal and illegal drugs pose new and growing health threats, especially among Pantanal youth, thus requiring studies to better characterize these drug users. The Brazilian Pantanal, a UNESCO World Heritage Site, suffers from anthropogenic effects such as changes in the production process, land occupation, and intensification in the flow of people, potentiated by precarious living conditions, sanitation, and health services. This situation demands epidemiological research that takes the local biome’s specificities into account. Issues like emerging and reemerging diseases, environmental pollution, external causes, ways of life, and health conditions among the Pantanal people will need to be closely interwoven with climate change and global contact. Research priorities in epidemiology in the Brazilian Pantanal