# Geographical Scale Effects on the Analysis of Leptospirosis Determinants

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*Int. J. Environ. Res. Public Health*

**2014**,

*11*(10), 10366-10383; https://doi.org/10.3390/ijerph111010366

## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Geographical Scales and Units of Data Aggregation

#### 2.2. Leptospirosis Incidence Data

#### 2.3. Environmental and Socioeconomic Data

#### 2.4. Geoprocessing Techniques

#### 2.5. Statistical Analysis

**Table 1.**Socioeconomic and environmental indicators at three geographical scales and their respective units of aggregation.

Indicators | Geographical Scale (Unit of Aggregation) | |||
---|---|---|---|---|

a. State (municipalities within the Rio de Janeiro state; n = 92) | b.b. Municipal (Neighborhoods in the Rio de Janeiro city; n = 158) | c. Local (Census Sectors of Jacarepaguá and Cidade de Deus; n = 652) | ||

1 | Incidence rate of leptospirosis (SINAN and Census IBGE) | Incidence rate of leptospirosis (SINAN and Census IBGE) | Incidence rate of leptospirosis (SINAN and Census IBGE) | |

2 | Altitude classification (FCIDE) | Proportion of areas prone to flooding (IPP) | Proportion of areas prone to flooding (IPP) | |

3 | Proportion of households connected to water systems (Census IBGE) | Proportion of households connected to water systems (Census IBGE) | Proportion of households connected to water systems (Census IBGE) | |

4 | Proportion of households connected to sewage systems (Census IBGE) | Proportion of households connected to sewage systems (Census IBGE) | Proportion of households connected to sewage systems (Census IBGE) | |

5 | Proportion of households with at least one bathroom (Census IBGE) | Proportion of households with at least one bathroom (Census IBGE) | Proportion of households with at least one bathroom (Census IBGE) | |

6 | Proportion of households with systematic garbage collection (Census IBGE) | Proportion of households with systematic garbage collection (Census IBGE) | Proportion of households with systematic garbage collection (Census IBGE) | |

7 | Proportion of population living in slum areas (Census IBGE) | Proportion of population living in slum areas (Census IBGE) | Proportion of population living in slum areas (Census IBGE) | |

8 | Proportion of residents with at least a high school degree (Census IBGE) | Proportion of residents with at least a high school degree (Census IBGE) | Proportion of residents with at least a high school degree (Census IBGE) | |

9 | Population density (Census IBGE and basemap) | Population density (Census IBGE and basemap) | Population density (Census IBGE and basemap) | |

10 | Proportion of land use (Iqm/CIDE): urban area, urban area not consolidated, cropland/pasture/grassland and forestland | Proportion of land use (IPP): urban area, urban area not consolidated, cropland/pasture/grassland and forestland | Proportion of land use (IPP): urban area, urban area not consolidated, cropland/pasture/grassland and forestland | |

11 | Interaction between indicators | Interaction between indicators | Interaction between indicators | |

Indicative map |

#### 2.6. Indicator Definitions:

- (1-a, b, c) (Number of Leptospirosis Cases (SINAN)/population (IBGE)) ×100,000 state level-unit of aggregation municipality; ×10,000 municipal level-unit of aggregation neighborhoods and ×1000 local level-unit of aggregation census sectors. Incidence rate calculations were different among three geographical scales due to large variation in the population at different units of aggregation.
- (2-a) Iqm Table with the altitude (m) of each municipality—2003 (FCIDE)
- (2-b) Intersection between neighborhood map and map of areas prone to flooding using SIG software ×100
- (2-c) Intersection between maps of census sectors of Jacarepaguá and Cidade de Deus RAs and map of areas prone to flooding using SIG software × 100
- (3-a, b, c) (Number of households connected to water systems/Total number of households) × 100
- (4-a, b, c) (Number of households connected to sewage systems/Total number of households) × 100
- (5-a, b, c) (Number of households with at least one bathroom/Total number of households) × 100
- (6-a, b, c) (Number of households with systematic garbage collection/Total number of households) × 100
- (7-a, b, c) (Total number of people living in slums/Total Population) × 100
- (8-a, b, c) (Number of residents with at least a high school degree/Total number of residents) × 100
- (9-) Population (IBGE Census of 2000)/Area (Km
^{2}) for municipalities, neighborhoods and census sectors. - (10-a, b, c) From Landsat images of 2001, CIDE and IPP calculate Iqm for Rio de Janeiro state and Rio de Janeiro city respectively. An operation that intersects between aggregation units used in this work and the land use classifications was performed. Thus polygons with the classification of different land uses within each unit of aggregation was created. Subsequently the ratio of the area of different land uses was calculated: municipalities of the state of Rio de Janeiro; neighborhoods in the city of Rio de Janeiro and the census tracts of the administrative region of Jacarepaguá.

## 3. Results and Discussion

#### 3.1. Leptospirosis Incidence Results

**Figure 1.**Leptospirosis incidence rates in the municipalities of Rio de Janeiro state during epidemic (

**A**) and (

**B**) endemic periods, respectively.

**Figure 2.**Leptospirosis incidence rates in the neighborhoods of Rio de Janeiro city during epidemic (

**A**) and (

**B**) endemic periods, respectively.

**Figure 3.**Leptospirosis incidence rates in the census sector of the Jacerapaguá and Cidade de Deus RAs during (

**A**) epidemic and (

**B**) endemic periods, respectively.

**Table 2.**Results of non-parametric Spearman’s rank correlation tests within the epidemic period (1996) at the three geographical scales.

State Level | Municipal Level | Local Level | ||||
---|---|---|---|---|---|---|

Indicators | Correlation Coefficient | p-value | Correlation Coefficient | p-value | Correlation Coefficient | p-value |

Sanitation | ||||||

Proportion of households supplied with water | 0.241 | 0.022 | −0.204 ^{*} | 0.010 | −0.001 | 0.975 |

Proportion of households connected to sewage | 0.218 | 0.038 | −0.114 | 0.153 | −0.067 | 0.085 |

Proportion of households with garbage collection | 0.287 ^{*} | 0.006 | −0.071 | 0.373 | −0.046 | 0.239 |

Poverty | ||||||

Proportion of population living in slums | 0.429 ^{*} | 0.000 | 0.082 | 0.303 | −0.180 ^{*} | 0.000 |

Proportion of households with at least one bathroom | 0.146 | 0.169 | 0.017 | 0.833 | −0.029 | 0.467 |

Proportion of householders with complete High School | 0.211 | 0.044 | −0.083 | 0.299 | −0.010 | 0.791 |

Environment | ||||||

Altitude/flooding area | −0.04 | 0.700 | 0.046 | 0.566 | 0.142 ^{*} | 0.000 |

Population density | 0.350 ^{*} | 0.001 | −0.045 | 0.577 | −0.152 ^{*} | 0.000 |

Proportion of urban use | 0.387 ^{*} | 0.000 | −0.254 ^{*} | 0.001 | 0.033 | 0.405 |

Proportion of non-consolidated urban use | ----------- | --------- | 0.323 ^{*} | 0.000 | 0.002 | 0.966 |

Proportion of field/pasture/anthropogenic use | −0.09 | 0.393 | 0.162 | 0.042 | --------- | -------- |

Proportion of rural use | −0.16 | 0.133 | −0.002 | 0.978 | −0.044 | 0.264 |

^{*}Correlation is significant at the 0.02 level (2-tailed); Only the incidence rates refer to 1996, the other variables refer to 2000.

**Table 3.**Results of non-parametric Spearman’s rank correlation tests within the endemic period (1997–1998) at the three geographical scales.

State level | Municipal level | Local level | ||||
---|---|---|---|---|---|---|

Indicators | Correlation Coefficient | p-value | Correlation Coefficient | p-value | Correlation Coefficient | p-value |

Sanitation | ||||||

Proportion of households supplied with water | 0.268 ^{*} | 0.01 | −0.156 | 0.050 | −0.017 | 0.671 |

Proportion of households connected to sewage | 0.141 | 0.183 | −0.182 ^{*} | 0.022 | 0.008 | 0.832 |

Proportion of households with garbage collection | 0.162 | 0.126 | −0.222 ^{*} | 0.005 | 0.003 | 0.932 |

Proportion of population living in slums | 0.484 ^{*} | 0.000 | 0.234 ^{*} | 0.003 | −0.067 | 0.086 |

Proportion of households with at least one bathroom | 0.256 ^{*} | 0.014 | 0.244 ^{*} | 0.002 | −0.028 | 0.476 |

Proportion of householders with complete High School | 0.346 ^{*} | 0.001 | −0.278 ^{*} | 0.000 | −0.026 | 0.505 |

Poverty | ||||||

Environmental | ||||||

Altitude/flooding area | −0.005 | 0.959 | 0.130 | 0.104 | 0.014 | 0.719 |

Population density | 0.253 ^{*} | 0.015 | 0.111 | 0.164 | −0.095 ^{*} | 0.015 |

Proportion of urban use | 0.309 ^{*} | 0.003 | −0.065 | 0.416 | 0.013 | 0.733 |

Proportion of non-consolidated urban use | ----------- | --------- | 0.120 | 0.133 | 0.011 | 0.775 |

Proportion of field/pasture/anthropogenic | −0.099 | 0.349 | 0.169 | 0.034 | ----------- | --------- |

Proportion of rural use | −0.257 ^{*} | 0.014 | 0.115 | 0.150 | 0.01 | 0.802 |

^{*}Correlation is significant at the 0.02 level (2-tailed); Only the incidence rates refer to 1996, the other variables refer to 2000.

#### 3.1.1. State Level

#### 3.1.2. Municipal Level

#### 3.1.3. Local Level

#### 3.2. Discussion

## 4. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

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## Share and Cite

**MDPI and ACS Style**

Gracie, R.; Barcellos, C.; Magalhães, M.; Souza-Santos, R.; Barrocas, P.R.G. Geographical Scale Effects on the Analysis of Leptospirosis Determinants. *Int. J. Environ. Res. Public Health* **2014**, *11*, 10366-10383.
https://doi.org/10.3390/ijerph111010366

**AMA Style**

Gracie R, Barcellos C, Magalhães M, Souza-Santos R, Barrocas PRG. Geographical Scale Effects on the Analysis of Leptospirosis Determinants. *International Journal of Environmental Research and Public Health*. 2014; 11(10):10366-10383.
https://doi.org/10.3390/ijerph111010366

**Chicago/Turabian Style**

Gracie, Renata, Christovam Barcellos, Mônica Magalhães, Reinaldo Souza-Santos, and Paulo Rubens Guimarães Barrocas. 2014. "Geographical Scale Effects on the Analysis of Leptospirosis Determinants" *International Journal of Environmental Research and Public Health* 11, no. 10: 10366-10383.
https://doi.org/10.3390/ijerph111010366