Spatial analysis of hemorrhagic fever with renal syndrome in China

Abstract

Background: Hemorrhagic fever with renal syndrome (HFRS) is endemic in many provinces with high incidence in mainland China, although integrated intervention measures including rodent control, environment management and vaccination have been implemented for over ten years. In this study, we conducted a geographic information system (GIS)-based spatial analysis on distribution of HFRS cases for the whole country with an objective to inform priority areas for public health planning and resource allocation.

Methods: Annualized average incidence at a county level was calculated using HFRS cases reported during 1994-1998 in mainland China. GIS-based spatial analyses were conducted to detect spatial autocorrelation and clusters of HFRS incidence at the county level throughout the country.

Results: Spatial distribution of HFRS cases in mainland China from 1994 to 1998 was mapped at county level in the aspects of crude incidence, excess hazard and spatial smoothed incidence. The spatial distribution of HFRS cases was nonrandom and clustered with a Moran's I = 0.5044 (p = 0.001). Spatial cluster analyses suggested that 26 and 39 areas were at increased risks of HFRS (p < 0.01) with maximum spatial cluster sizes of < or = 20% and < or = 10% of the total population, respectively.

Conclusion: The application of GIS, together with spatial statistical techniques, provide a means to quantify explicit HFRS risks and to further identify environmental factors responsible for the increasing disease risks. We demonstrate a new perspective of integrating such spatial analysis tools into the epidemiologic study and risk assessment of HFRS.

Figure 1

Annualized average incidence of HFRS in mainland China during 1994 – 1998.

Figure 2

Excess hazard map of HFRS in mainland China from 1994 to 1998.

Figure 3

Spatially smoothed percentile map of HFRS in mainland China from 1994 to 1998.

Figure 4

The continuous distribution map of HFRS in mainland China from 1994 to 1998.

Figure 5

a. The Moran scatter plot for annualized average incidence of HFRS. b. The histogram for significance assessment of Moran's I.

Figure 6

Spatial distribution of identified clusters of HFRS cases with significant higher incidences using the maximum cluster size ≤ 20% of the total population in mainland China, 1994–1998.

Figure 7

Spatial distribution of identified clusters of HFRS cases with significant higher incidences using the maximum cluster size ≤ 10% of the total population in mainland China, 1994–1998.