Study of the relationship between Aedes (Stegomyia) aegypti egg and adult densities, dengue fever and climate in Mirassol, state of São Paulo, Brazil.

The purpose of this study was to examine the relationship between Aedes aegypti egg and adult density indices, dengue fever and climate in Mirassol, state of São Paulo, Brazil, between November 2004-November 2005. Weekly collections of adults and eggs were made using, respectively, manual aspirators and oviposition traps that produced four entomological indices (positivity and average of females and eggs). Weekly incidence coefficients were calculated based on dengue cases. Each week, the data obtained from entomological indices were related to each other, dengue, and climate variables. The first index to show an association with dengue transmission was the female average, followed by female positivity and egg average. Egg positivity did not show a relationship with risk for dengue, but was sensitive to identifying the presence of the vector, principally in dry seasons. The relationship between climatic factors, the vector and the disease found in this study can be widely employed in planning and undertaking dengue surveillance and control activities, but it is a tool that has not been considered by the authorities responsible for controlling the disease. In fact, this relationship permits the use of information about climate for early detection of epidemics and for establishing more effective prevention strategies than currently exist.

Assessment of the relationship between entomologic indicators of Aedes aegypti and the epidemic occurrence of dengue virus 3 in a susceptible population, São José do Rio Preto, São Paulo, Brazil.

The aims of this study were to describe the occurrence of dengue in space and time and to assess the relationships between dengue incidence and entomologic indicators. We selected the dengue autochthonous cases that occurred between September 2005 and August 2007 in São José do Rio Preto to calculate incidence rates by month, year and census tracts. The monthly incidence rates of the city were compared to the monthly Breteau indices (BI) of the São José do Rio Region. Between December 2006 and February 2007, an entomological survey was conducted to collect immature forms of Aedes aegypti in Jaguaré, a São José do Rio Preto neighborhood, and to obtain entomological indices. These indices were represented using statistical interpolation. To represent the occurrence of dengue in the Jaguaré neighborhood in 2006 and 2007, we used the Kernel ratio and to evaluate the relationship between dengue and the entomological indices, we used a generalized additive model in a spatial case-control design. Between September 2005 and August 2007, the occurrence of dengue in São José do Rio Preto was almost entirely caused by DENV3, and the monthly incidence rates presented high correlation coefficients with the monthly BI. In Jaguaré neighborhood, the entomological indices calculated by hectare were better predictors of the spatial distribution of dengue than the indices calculated by properties, but the pupae quantification did not show better prediction qualities than the indices based on the container positivity, in relation to the risk of dengue occurrence. The fact that the municipality's population had a high susceptibility to the serotype DENV3 before the development of this research, along with the almost total predominance of the occurrence of this serotype between 2005 and 2007, facilitated the analysis of the epidemiological situation of the disease and allowed us to connect it to the entomological indicators.

Spatial analysis of leprosy incidence and associated socioeconomic factors.

OBJECTIVE: To identify clusters of the major occurrences of leprosy and their associated socioeconomic and demographic factors. METHODS: Cases of leprosy that occurred between 1998 and 2007 in São José do Rio Preto (southeastern Brazil) were geocodified and the incidence rates were calculated by census tract. A socioeconomic classification score was obtained using principal component analysis of socioeconomic variables. Thematic maps to visualize the spatial distribution of the incidence of leprosy with respect to socioeconomic levels and demographic density were constructed using geostatistics. RESULTS: While the incidence rate for the entire city was 10.4 cases per 100,000 inhabitants annually between 1998 and 2007, the incidence rates of individual census tracts were heterogeneous, with values that ranged from 0 to 26.9 cases per 100,000 inhabitants per year. Areas with a high leprosy incidence were associated with lower socioeconomic levels. There were identified clusters of leprosy cases, however there was no association between disease incidence and demographic density. There was a disparity between the places where the majority of ill people lived and the location of healthcare services. CONCLUSIONS: The spatial analysis techniques utilized identified the poorer neighborhoods of the city as the areas with the highest risk for the disease. These data show that health departments must prioritize politico-administrative policies to minimize the effects of social inequality and improve the standards of living, hygiene, and education of the population in order to reduce the incidence of leprosy.

Spatial analysis of leprosy incidence and associated socioeconomic factors / Análise espacial da incidência de hanseníase e fatores socioeconômicos associados / Análisis espacial de la incidencia de lepra y factores socioeconómicos asoci

OBJECTIVE: To identify clusters of the major occurrences of leprosy and their associated socioeconomic and demographic factors. METHODS: Cases of leprosy that occurred between 1998 and 2007 in São José do Rio Preto (southeastern Brazil) were geocodified and the incidence rates were calculated by census tract. A socioeconomic classification score was obtained using principal component analysis of socioeconomic variables. Thematic maps to visualize the spatial distribution of the incidence of leprosy with respect to socioeconomic levels and demographic density were constructed using geostatistics. RESULTS: While the incidence rate for the entire city was 10.4 cases per 100,000 inhabitants annually between 1998 and 2007, the incidence rates of individual census tracts were heterogeneous, with values that ranged from 0 to 26.9 cases per 100,000 inhabitants per year. Areas with a high leprosy incidence were associated with lower socioeconomic levels. There were identified clusters of leprosy cases, however there was no association between disease incidence and demographic density. There was a disparity between the places where the majority of ill people lived and the location of healthcare services. CONCLUSIONS: The spatial analysis techniques utilized identified the poorer neighborhoods of the city as the areas with the highest risk for the disease. These data show that health departments must prioritize politico-administrative policies to minimize the effects of social inequality and improve the standards of living, hygiene, and education of the population in order to reduce the incidence of leprosy.

OBJETIVO: Identificar áreas com maior ocorrência de casos de hanseníase e fatores socioeconômicos e demográficos associados. MÉTODOS: Casos de hanseníase ocorridos entre 1998 e 2007 em São José do Rio Preto, SP, foram geocodificados e coeficientes de incidência foram calculados por setores censitários. Por meio da técnica de análise de componentes principais, obteve-se um escore para classificação socioeconômica. O uso do método de krigagem ordinária resultou em mapas temáticos para visualização da distribuição espacial da incidência de hanseníase, do nível socioeconômico e da densidade demográfica. RESULTADOS: Enquanto a incidência para toda a cidade foi de 10,4 casos por 100.000 habitantes por ano, entre 1998 e 2007, as incidências por setores censitários foram heterogêneas, variando de zero a 26,9 casos por 100.000 habitantes por ano. Houve concordância entre áreas com valores mais altos de incidência e menores níveis socioeconômicos. Foram identificados aglomerados de casos de hanseníase. Não foi observada associação da doença com densidade demográfica. Detectou-se falta de relação entre os locais de moradia da maioria dos doentes e a localização dos serviços de saúde. CONCLUSÕES: As técnicas de análise espacial utilizadas permitiram caracterizar as áreas mais deficitárias do município como as de maior risco para hanseníase.

OBJETIVO: Identificar áreas con mayor ocurrencia de casos de lepra y factores socioeconómicos y demográficos asociados. MÉTODOS: Casos de lepra ocurridos entre 1998 y 2007 en Sao José do Rio Preto, Sureste de Brasil, fueron geocodificados y se calcularon los coeficientes de incidencia por sectores censados. Por medio de la técnica de análisis de componentes principales, se obtuvo un escore para clasificación socioeconómica. El uso del método de krigage ordinaria resultó en mapas temáticos para visualización de la distribución espacial de la incidencia de lepra, del nivel socioeconómico y de la densidad demográfica. RESULTADOS: Mientras la incidencia para toda la ciudad fue de 10,4 casos por 100.000 habitantes por año, entre 1998 y 2007, las incidencias por sectores censados fueron heterogéneas, variando de cero a 26,9 casos por 100.000 habitantes por año. Hubo concordancia entre áreas con valores más altos de incidencia y menores niveles socioeconómicos. Se identificaron aglomerados de casos de lepra. No fue observada asociación de la enfermedad con densidad demográfica. Se detectó falta de relación entre los lugares de vivienda de la mayoría de los enfermos y la localización de los servicios de salud. CONCLUSIONES: Las técnicas de análisis espacial utilizadas permitieron caracterizar las áreas más deficitarias del municipio como las de mayor riesgo para lepra.

Study of the relationship between Aedes (Stegomyia) aegypti egg and adult densities, dengue fever and climate in Mirassol, state of São Paulo, Brazil

The purpose of this study was to examine the relationship between Aedes aegypti egg and adult density indices, dengue fever and climate in Mirassol, state of São Paulo, Brazil, between November 2004-November 2005. Weekly collections of adults and eggs were made using, respectively, manual aspirators and oviposition traps that produced four entomological indices (positivity and average of females and eggs). Weekly incidence coefficients were calculated based on dengue cases. Each week, the data obtained from entomological indices were related to each other, dengue, and climate variables. The first index to show an association with dengue transmission was the female average, followed by female positivity and egg average. Egg positivity did not show a relationship with risk for dengue, but was sensitive to identifying the presence of the vector, principally in dry seasons. The relationship between climatic factors, the vector and the disease found in this study can be widely employed in planning and undertaking dengue surveillance and control activities, but it is a tool that has not been considered by the authorities responsible for controlling the disease. In fact, this relationship permits the use of information about climate for early detection of epidemics and for establishing more effective prevention strategies than currently exist.