Epidemiological Characteristics and Spatiotemporal Trend Analysis of Human Brucellosis in China, 1950-2018

Abstract

The rate of brucellosis, a zoonotic disease, has rapidly increased in humans brucellosis(HB) in recent years. In 1950-2018, a total of 684,380 HB cases (median 2274/year (interquartile range (IQR) 966-8325)) were reported to the National Infectious Disease Surveillance System in mainland China. The incidence of HB peaked in 2014 (4.32/100,000), and then showed a downward trend; we predict that it will maintain a steady downward trend in 2019-2020. Since 2015, the incidence of HB has shown opposite trends in the north and south of China; rates in the north have fallen and rates in the south have increased. In 2004-2018, the most significant increases in incidence of HB were in Yunnan (IQR 0.002-0.463/100,000), Hubei (IQR 0.000-0.338/100,000), and Guangdong (IQR 0.015-0.350/100,000). The areas where HB occurs have little overlap with areas with high per capita GDP in China. The "high-high" clusters of HB are located in northeastern China (Inner Mongolia, Heilongjiang, Jilin, Liaoning, Ningxia, Shanxi, and Gansu), and the "low-low" clusters of HB are located in southern China (Yunnan, Jiangxi, Shanghai, Guangxi, Guangdong, Zhejiang, Guizhou, and Hunan). In recent years, the incidence of HB in China has been controlled to some extent, but the incidence of HB has increased in southern China, and the disease has spread geographically in China from north to south. Further research is needed to address this change and to continue to explore the relationship between the incidence of HB and relevant factors.

Keywords: China; GDP; brucellosis; epidemiology; humans; spatiotemporal trend; zoonoses.

Figure 1

Human brucellosis (HB) cases (N = 684,380), mainland China, 1950–2018. (A) The number of cases reported by year (orange pillar) and annual incidence (blue line). (B) Autoregressive integrated moving average model (ARIMA) used to predict 2019–2020 data based on monthly numbers from 2005 to 2018, using 80% CI (light blue) and 95% CI (dark blue) monthly cases (blue line).

Figure 2

Annual incidence distribution of brucellosis in mainland China in 2004–2018 (by 3 year period).

Figure 3

(A) The incidence (1/100,000) of HB in northern (blue line) and southern (orange line) China from 2004 to 2018. (B) Heat map of provinces with HB cases in southern China.

Figure 4

Annual incidence and gross domestic product (GDP) (/100 million yuan) distribution in mainland China, 2004–2018 (by 3 year period).

Figure 5

The Moran’s I scatter plots of the annual incidence of HB in China from 2004 to 2018 (by 3 year period). The first to fourth quadrants of the Moran scatter plot correspond to high–high, low–high, low–low, and high–low correlations of local Moran’s I. The horizontal axis of the Moran scatter plot is the observed and normalized z-score ($Z_i=\frac{X_i-X}{S}$) for a specific province or district, and the vertical axis is the weighted sum of observed and normalized z-score for the neighboring provinces or districts ($W_{Z_i}={\displaystyle \sum }_{i=1}^n{w}_{ij}{z}_j$ ). The individual dots represent the specific 34 provinces or districts.

Figure 6

Moran’s I chart of HB incidence rate per 100,000 residents in China from 2004 to 2018 (by 3 year period). (A) Local Moran’s I cluster map. (B) Local Moran’s I significance map.