Geographic and Temporal Trends in Influenzalike Illness, Japan, 1992–1999

Abstract

Kriging analysis improved visualization and understanding of trends in seasonal ILI activity in Japan.

Spatiotemporal Analysis of Influenza Epidemics in Japan

“…), and the latter [10] pointed to major traffic pathways and local contact networks. Prevailing westerlies appear to play an important role in the case of Japan, which was noted by Sakai et al [13]. The data used in that study were cases reported from 1992 to 1999, and the Kriging method was used for analysis.…”

“…It is important to identify such regularities through quantitative analysis, and then to investigate the causes of these regularities. To date, spatiotemporal analyses of influenza epidemics have been performed in France [3,4], Scotland [5], 20 European countries [6], Australia [4], Brazil [7], the United States [4,[8][9][10][11], China [12], and Japan [13,14]. These studies identified several regularities in influenza epidemics: west-to-east spread of peak influenza activity, spatiotemporal epidemic synchrony, close correlation with movement of people, relation with mortality pattern, and so on.…”

“…15.2). While Sakai et al examined the influenza epidemic data in Japan from 1992 to December 1999, using the Kriging method [13], the present study has investigated data from 1999 to 2014, using wavelet analysis. The difference of the data period and analysis is also intriguing.…”

Modeling Properties of Influenza-Like Illness Peak Events with Crossing Theory

“…Valuable information concerning epidemics, such as spatial variations, dynamics and periodicity, cannot be derived from the generally short historic records by this definition. Sakai et al [9] slightly modified this approach by identifying the annual maximum of the smoothed data. They incorporated information from weeks before and after the peak event by smoothing data with a five-week unweighted moving average of weekly reported cases.…”

Combining Global and Local Estimates for Spatial Distribution of Mosquito Larval Habitats

“…According to the semivariogram model, kriging methods estimate the value at an unsampled location using values of adjacent samples and distances from the unsampled location to these samples. Kriging methods have been used in many healthrelated studies (Walter, 1994;Diggle et al, 1998;Klienschmidt et al, 2000;Sakai et al, 2004). Ordinary kriging is used in this study to model the spatially dependent local variation in the residuals.…”