Reinaldo Souza-Santos

Análise de dados espaciais em saúde pública: métodos, problemas, perspectivas

Studies in which spatial distribution and geographic information systems (GIS) play a central role are becoming more common in the public health literature. However, methods and software to implement such approaches still pose serious limitations, due to unfriendliness and lack of integration. Additionally, most researchers and public health professionals are not familiar with either the techniques or the software. The aim of this work, besides presenting a systematic review of spatial analysis in health, is to discuss some representative applications of methods that deal with the analysis of spatial patterns of health events, analyzing advantages, disadvantages, and applicability of the proposed models in ecological and health services utilization studies.

Spatial analysis of Aedes aegypti larval distribution in the Ilha do Governador neighborhood of Rio de Janeiro, Brazil

This study aims to help expand knowledge on Aedes aegypti in Rio de Janeiro, based on spatial analysis of the mosquitos breeding sites in the neighborhood of Ilha do Governador, Rio de Janeiro, from June 1992 to July 1994. Use of spatial analysis techniques is proposed for vector surveillance and control. Information obtained from the National Health Foundation shows which city blocks were positive for A. aegypti larvae and the number of dwellings per block that were used for the analysis. A smoothing method, a Gaussian Kernel, was used in the spatial distribution analysis. Breaks in National Health Foundation intervention activities were observed between cycles 4 and 5 and 5 and 6, respectively, followed by increases in vector density and vector-positive areas. Permanently positive areas, like slums and a military compound, display the persistence of favorable environmental conditions for oviposition and larval growth, indicating flaws in the vector control program. Although Kernel is an exploratory analytical method involving subjective interpretation, it provides easy and fast visualization of sites subject to different degrees of risk, unaffected by existing political and administrative territorial apportionment.

Identification of key areas for Aedes aegypti control through geoprocessing in Nova Iguaçu, Rio de Janeiro State, Brazil

This study discusses the use of geoprocessing to identify key areas for Aedes aegypti control, based on the infestation index obtained in the Aedes aegypti Infestation Index Rapid Survey (LIRAa). The study was conducted in November 2004 in Nova Iguaçu, Rio de Janeiro State, Brazil. The results were analyzed on two scales, neighborhoods and blocks, with the building infestation index assigned to the neighborhood polygons and the Breteau index to the blocks. Kernel estimation was used in the spatial pattern analysis. The Breteau index spatial distribution showed five areas with high and medium density of positive Ae. aegypti breeding sites, highlighting small block clusters with high larval density, strategic for vector control. Based on the results, we recommend this method for dengue vector surveillance.

Change in age pattern of persons with dengue, northeastern Brazil

To the Editor: Approximately 40% of the world’s population is at risk for dengue (1). Epidemiologic characteristics of dengue differ by region, and disease incidence varies by patient age. In Southeast Asia, incidence of dengue fever (DF) and dengue hemorrhagic fever (DHF) is highest among children (2,3); in the Western Hemisphere, incidence of these diseases is higher among adults. In Brazil, which has ≈80% of dengue cases in the Western Hemisphere, adults are at risk for dengue virus (DENV) infection (3,4). However, in 2007, a total of 53% of persons in Brazil hospitalized with DHF were children <15 years of age; this proportion was highest (65.4%) in children in northeastern Brazil (5). In Ceara, a state in northeastern Brazil, DENV-1 epidemics have occurred since 1987. DHF cases have been reported since 1994 when DENV-2 was identified. In 2003, a severe DENV-3 epidemic occurred, and DHF incidence was high among adults (6). However, since 2007, incidence of DENV infection has been highest among children (7). To better understand factors that could affect this change in risk by age group, we studied the temporal progression of age distribution of persons with dengue during 1998–2008 in Ceara. We used data for Ceara from the National System of Notifiable Diseases (DF and DHF cases), the Hospital Admission Data System (dengue hospitalizations) (8), and the Central Public Health Laboratory (virus isolation). For each age group ( 60 years), we calculated incidence of DF and hospitalization rate for DHF. We also calculated proportions of dengue serotypes per year (2001–2008). Medians for continuous variables were compared by using the Kruskal-Wallis test. Analyses were performed by using Epi Info version 6.0 software (Centers for Disease Control and Prevention, Atlanta, GA, USA). From 1998 (10.8 cases/100,000 persons) through 2007 (236.7 cases/100,000 persons), DF incidence was lowest among persons 60 years of age (305.6, 331.5, and 249.9 cases/100,000 persons, respectively). Since 2007, the incidence of DHF among children was already higher (4,884 cases/100,000 persons) than among the other age groups (3,261, 3,387 and 2,789 cases/100,000 persons, respectively). In 2008, incidence of DHF among children was 8,992 cases/100,000 persons, which was 2× that among persons 10–19 and 20–59 years of age and >3× that among persons >60 years of age. Median age of persons with DHF decreased from 38 years in 2001 to 18 years in 2008 (p<0.0001). Children <10 years age, who in 2001 accounted for 5% of all cases, accounted for 33% of cases in 2008. The hospitalization rate for dengue among children in Ceara followed a pattern similar to that for DHF and increased for children 40% of isolations. At this time, DENV-2 and DENV-1 represented 7.4% and 48.5% of isolations, respectively. DENV-3 then predominated in Ceara until 2006 when DENV-2 reemerged (1.4%). DENV-2 became the predominant serotype in 2007 (84%) and 2008 (76.1%) (Table). The increase in DHF incidence among children in Ceara during 2007–2008 was greater than the overall increase in Brazil (4,5). Because the predominant serotype in Ceara in 2007–2008 was DENV-2, two hypotheses may explain this phenomenon. First, a more virulent DENV-2 may have been introduced. Genetic sequencing of DENV-2 circulating in another state in Brazil during the 2008 epidemic, compared with the 1990 and 1998 epidemics, showed that all isolates had the same genotype (American/Asiatic); only a 2% had a phylogenetic change (9). Such a small difference cannot explain this change in the age group affected by dengue. Second, the time when 3 serotypes circulated in Ceara may not have favored development of antibodies against DENV-3 in children <10 years of age, although they were susceptible to DENV-2. DENV-1 and DENV-2 were circulating in Ceara before 2002 and caused DF epidemics and a few DHF cases. However, these diseases occurred predominantly in adults. Conversely, children had little likelihood of being infected with DENV-2 because the incidence of dengue before 2002 was low and the 2000 birth cohort had little contact with DENV-2, which was no longer circulating. Thus, most persons susceptible to DENV-2 were children. DENV-3 was circulating during 2003–2006 and affected persons of all ages. Thus, when DENV-2 reemerged in 2006, many adults in Ceara already had antibodies against it. However, children had no antibodies against DENV-2, although some had antibodies against DENV-3. This immunologic difference may have caused the higher incidence of dengue among children in Ceara during 2007–2008, particularly in view of severity of the 2 epidemics, increased risk for DHF (10), and number of hospitalizations for dengue during this period. Table Confirmed cases of dengue fever and dengue hemorrhagic fever, Ceara, Brazil, 1998–2008*

Análise espacial da ocorrência de dengue e condições de vida na cidade de Nova Iguaçu, Estado do Rio de Janeiro, Brasil

The reemergence, spread, and persistence of dengue are currently challenging the Brazilian health system. Factors related to living conditions have been addressed to understand different health outcomes. This study examines the occurrence of dengue and its relationship to living conditions in the city of Nova Iguacu, Rio de Janeiro State, from 1996 to 2004. Data on dengue occurrence were obtained from the Brazilian National Disease Notification System (SINAN). A composite indicator of socioeconomic and urban infrastructure variables was created to characterize the prevailing living conditions, using 2000 census data. Operations between layers were used to identify spatial associations between the composite indicator and dengue incidence by neighborhood. The results do not show a linear relationship between poor living conditions and disease occurrence, but the spatial patterns indicated greater susceptibility of areas with inequalities in living conditions and behind highway access routes. The results also suggest that such inequalities can influence the dengue time trend. Thus, models that consider the interaction between socioeconomic variables (and not only the quantification of social indicators) can be useful for dengue surveillance.

Análise espacial dos focos de Biomphalaria glabrata e de casos humanos de esquistossomose mansônica em Porto de Galinhas, Pernambuco, Brasil, no ano 2000

This article provides information on the spatial distribution of schistosomiasis, correlating snail foci with human cases using spatial analysis. The locations studied were Merepe III, Pantanal, Salinas, and Soco, comprising 70% of the populated area of Porto de Galinhas. Malacological and parasitological surveys by a CPqAM/ FIOCRUZ team at the location where an epidemic occurred in 2000 identified 15 foci of infected B. glabrata. Human cases were also diagnosed and recorded according to residential block. Spatial analysis was performed using the TerraView computer program and Kernel intensity estimation. Total infection rates, considering all collection stations marked out per location, varied from 15% to 32.4%. The 15 infected B. glabrata foci included 9 in Merepe, 2 in Soco, 3 in Salinas, and 1 in Pantanal. The results suggest a strong spatial trend in the risk of schistosomiais transmission in Salinas and Soco. In Merepe, with the most foci and where foci were closer together, individual focal infection rates were lower. Spatial analysis thus showed less concentration of risk as compared to other locations studied. As for human cases, two high-intensity areas were observed, shown on the map in darker colors.

Fatores associados à ocorrência de formas imaturas de Aedes aegypti na Ilha do Governador, Rio de Janeiro, Brasil

Aedes aegypti is the vector of dengue, a disease that can result in epidemics. Ecological studies are important because different geographical populations of the vector may differ in their bio-ecological characteristics, which can be helpful in guiding control actions. The objective of this study was to identify and to analyze some factors associated with the occurrence of immature forms of A. aegypti on Ilha do Governador, Rio de Janeiro, using data from the National Health Foundation (FNS). The results showed that 58.04% of all the containers examined were supports for plant pots, and plastic or glass cans discarded in the yard. The highest percentages of positive breeding sites were observed in tires (1.41%), wells and cisterns (0.93%), and barrels and large metal cans (0.64%). In the summer, the proportion of positivity was higher for big containers used for water storage and for containers discarded in the yard. In the winter the proportion was higher for small containers used for water storage. The highest rates of positive containers were observed after three months without FNS activities. Our results show the necessity to continue the control, and suggest that less attention was paid to small containers during the winter by FNS. Factorial analysis showed that the determinant factor for the ocurrence of immature forms of A. aegypti is represented by environmental factors, while elimination and treatment of breeding sites by FNS play a less important role, a fact possiblly causing the maintenance of immature forms of A. aegypti.

Quality of life related to oral health: contribution from social factors

UNLABELLED Sociodental indicators have been widely used in epidemiological research related to oral health, as they add the dimension of the impact of oral health on the quality of life of individuals and populations. Various studies have been done in order to validate new instruments to assess these subjective perceptions, however, the association between social parameters and impact on oral health-related quality of life (OHRQoL) has not been systematically studied, thus there is still doubt as to the role of the main social variables as OHRQoL impact modulators. This study aims to systematically review the literature in order to evidence the association between six social parameters and OHRQoL. Based on six exclusion criteria, the literature search revealed 40 eligible publications for analyses. The frequency of expected (positive) association between the social parameters and OHRQoL was greater than the non-expected (negative) associations for the six parameters. CONCLUSIONS The social conditions most clearly associated with the perception of negative impact on OHRQoL were: women, with poor education and low income, immigrants or people belonging to minority ethnic groups.

Análise espacial e determinação de áreas para o controle da malária no Estado de Rondônia

This paper discusses the use of spatial analysis for mapping the risk of malaria in the State of Rondônia between 1994 and 2005. Morans overall and local indices were used for spatial pattern analysis. Based on the Annual Parasitic Index, it can be stated that the municipalities forming the area at greater risk are those in which the urbanization process is more recent. They are characterized by higher population growth, greater number of settled families and high percentages of deforested area. The Moran map showed that the aggregated areas of municipalities at high risk of malaria have undergone a process of spreading into the northwestern and northeastern regions of the State. Among the municipalities considered to be at low risk, this process has taken place towards the southeast. The techniques used in this study deserve to be compared with the current methodology used by the Health Surveillance Department for determining areas at risk and financial transfers for malaria control..

Internação hospitalar e mortalidade por esquistossomose mansônica no Estado de Pernambuco, Brasil, 1992/2000

In order to investigate the historical trends, epidemiological profile, and spatial distribution of hospital admissions and deaths from schistosomiasis in the State of Pernambuco, Brazil, an analysis was conducted of data from the Hospital Information System and Mortality Information System from 1992 to 2000. The results showed a reduction in hospital admissions and mortality, while identifying more admissions and deaths among males. There was a lower percentage of deaths and admissions from schistosomiasis in individuals under 30 years of age. However, schistosomiasis is still of relevant magnitude, as evidenced by the number of deaths from this cause and the number of patients admitted to the hospital system in Pernambuco. A spatial analysis of the endemics distribution in the State showed that although from 1995 to 1999 there was a greater spread of admissions due to schistosomiasis in the municipalities (counties) of the Sertão (backlands) and São Francisco river valley, the number of municipalities with hospitalizations due to schistosomiasis decreased from 1995 to 1998, followed by an increase in 1999 and 2000.