The attack of novel avian influenza (H7N9) in east China caused a serious health crisis and public panic. In this paper, we empirically analyze the onset patterns of human cases of the novel avian influenza and observe several spatial and temporal properties that are similar to other infective diseases. More deeply, using the empirical analysis and modeling studies, we find that the spatio-temporal network that connects the cities with human cases along the order of outbreak timing emerges two-section-power-law edge-length distribution, indicating the picture that several islands with higher and heterogeneous risk straggle in east China. The proposed method is applicable to the analysis on the spreading situation in early stage of disease outbreak using quite limited dataset.

13 pages, 3 figures