Volume 10, Number 10—October 2004
Research
Geographic and Temporal Trends in Influenzalike Illness, Japan, 1992–1999
Figure 2

Figure 2. Timing of peak influenzalike illness epidemic activity by week in Japan. The isobars on the contour maps represent interpolated time of peak activity distributed spatially at 1-week intervals. The first week was defined when the peak week was observed first in any one of the prefectures in each season, and then the following weeks were numbered.