# Spatial Analysis of Severe Fever with Thrombocytopenia Syndrome Virus in China Using a Geographically Weighted Logistic Regression Model

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## Abstract

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## 1. Introduction

^{3}), leukocytopenia, multi-organ dysfunction and hemorrhagic tendency [1,2,3]. SFTS has been reported not only in at least 13 provinces in the central, eastern and northern regions of China [4], but also in North Korea [5], South Korea [6] and Japan [7]. SFTSV has spread wider and wider, posing an increasingly significant threat to the global health.

## 2. Materials and Methods

#### 2.1. Data Collection

#### 2.2. Modeling Methods

#### 2.2.1. Geographically Weighted Logistic Regression Model

#### 2.2.2. Model Evaluation

## 3. Results

#### 3.1. Spatial Distribution of Potential Determinants of SFTSV in Mainland China

#### 3.2. Frequency Analysis of Confirmed Cases of SFTSV

#### 3.3. Multicollinearity of Variables

#### 3.4. Construction of Models and Measures of Model Fit

#### 3.5. Estimation of Regression Coefficients of the GWLR Models

#### 3.6. Classification of Areas in Mainland China According to the Risk of SFTSV Cover Indicated by Meteorological Factors

## 4. Discussion

## 5. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## References

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**Figure 1.**Geographical distribution of SFTSV in mainland China from 2010 to 2012. SFTSV = severe fever with thrombocytopenia syndrome virus.

**Figure 2.**Study flow chart. AMP = average monthly precipitation; APPI = average proportion of primary industries; SFTS = severe fever with thrombocytopenia syndrome; APRP = average proportion of rural population; ARH = average relative humidity; AT = average temperature; GWLR = geographically weighted logistic regression; LR = logistic regression; SFTSV = severe fever with thrombocytopenia syndrome virus.

**Figure 3.**Spatial distribution of the five potential determinants of SFTSV cover: (

**a**) Average temperature (AT) from 2010 to 2012; (

**b**) Average monthly precipitation (AMP) from 2010 to 2012; (

**c**) Average relative humidity (ARH) from 2010 to 2012; (

**d**) Average proportion of rural population (APRP) from 2010 to 2012; and (

**e**) Average proportion of primary industries (APPI) from 2010 to 2012.

**Figure 4.**Regional distribution of the confirmed cases of SFTSV, 2010–2012. The statistics were summarized from GenBank available data until 13 March 2016. The numbers were not the actual total numbers of cases confirmed by the Ministry of Health in China.

**Figure 5.**Spatial distribution of the local relationships between SFTSV cover and the three meteorological factors: (

**a**) Estimated coefficient for average temperature; (

**b**) Estimated coefficient for average monthly precipitation; and (

**c**) Estimated coefficient for average relative humidity. SFTSV = severe fever with thrombocytopenia syndrome virus.

**Figure 7.**Classification of the provinces in mainland China according to the risk of SFTSV cover indicated by the three meteorological factors; AT = average temperature; AMP = average monthly precipitation; ARH = average relative humidity; SFTSV = severe fever with thrombocytopenia syndrome virus.

AT | AMP | ARH | APRP | APPI | |
---|---|---|---|---|---|

Unit | °C | mm | % | % | % |

AT | AMP | ARH | APRP | APPI | |
---|---|---|---|---|---|

VIF score | 1.50 | 3.25 | 3.33 | 2.71 | 2.74 |

Test | A | B | C | |||
---|---|---|---|---|---|---|

Model Type | LR | GWLR | LR | GWLR | LR | GWLR |

AIC | 37.586 | 37.242 | 39.738 | 39.651 | 38.796 | 38.545 |

AUC | 0.70 | 0.77 | 0.75 | 0.78 | 0.54 | 0.68 |

Coefficient Label | Minimum | Maximum | Mean | Range | Standard Error |
---|---|---|---|---|---|

Intercept | −3.324 | −1.218 | −1.506 | 2.106 | 0.426 |

AT | 0.912 | 2.792 | 1.133 | 1.880 | 0.363 |

AMP | −1.419 | −0.315 | −0.710 | 1.104 | 0.227 |

ARH | 0.002 | 1.786 | 0.571 | 1.789 | 0.382 |

Coefficient Label | Slight | Moderate | Strong |
---|---|---|---|

AT | 0.912–1.126 | 1.126–1.444 | 1.444–2.792 |

AMP | −1.419–−0.902 | −0.902–−0.625 | −0.625–−0.315 |

ARH | 0.003–0.300 | 0.300–0.772 | 0.772–1.786 |

**Table 6.**AT, AMP and ARH from 2010 to 2012 in the 13 provinces in China with high probabilities of SFTSV cover.

Year | Coefficient Label | Mean | Minimum | Maximum |
---|---|---|---|---|

2010 | AT (°C) | 25.2 | 23.3 | 26.8 |

AMP (mm) | 430.4 | 81.0 | 686.2 | |

ARH (%) | 69.2 | 49.1 | 78.3 | |

2011 | AT (°C) | 25.5 | 22.0 | 27.2 |

AMP (mm) | 415.3 | 113.5 | 681.2 | |

ARH (%) | 66.5 | 51.7 | 81.0 | |

2012 | AT (°C) | 25.9 | 22.8 | 27.7 |

AMP (mm) | 415.3 | 113.5 | 681.2 | |

ARH (%) | 68.2 | 52.7 | 81.0 |

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**MDPI and ACS Style**

Wu, L.; Deng, F.; Xie, Z.; Hu, S.; Shen, S.; Shi, J.; Liu, D.
Spatial Analysis of Severe Fever with Thrombocytopenia Syndrome Virus in China Using a Geographically Weighted Logistic Regression Model. *Int. J. Environ. Res. Public Health* **2016**, *13*, 1125.
https://doi.org/10.3390/ijerph13111125

**AMA Style**

Wu L, Deng F, Xie Z, Hu S, Shen S, Shi J, Liu D.
Spatial Analysis of Severe Fever with Thrombocytopenia Syndrome Virus in China Using a Geographically Weighted Logistic Regression Model. *International Journal of Environmental Research and Public Health*. 2016; 13(11):1125.
https://doi.org/10.3390/ijerph13111125

**Chicago/Turabian Style**

Wu, Liang, Fei Deng, Zhong Xie, Sheng Hu, Shu Shen, Junming Shi, and Dan Liu.
2016. "Spatial Analysis of Severe Fever with Thrombocytopenia Syndrome Virus in China Using a Geographically Weighted Logistic Regression Model" *International Journal of Environmental Research and Public Health* 13, no. 11: 1125.
https://doi.org/10.3390/ijerph13111125