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| Figure 1. Weekly reports of influenza virus isolation/detection, week 36/2011-week 25/2012 |
| Figure 2. Isolation/detection of influenza virus by prefecture, week 36/2011-week 25/2012 |
| Figure 3. Weekly isolation/detection of influenza virus by prefecture, weeks 21-25/2012 |
| In the 2011/12 season, isolation/detection of AH3 continues from week 36 of 2011 and largely increased from week 2 of 2012 and decreased after the peak of week 3. Isolations/detections of B/Yamagata lineage and B/Victoria lineage were first reported in week 39 and week 40 of 2011, respectively, and slightly increased from week 2 of 2012 and decreased after week 18. In addtion, isolations/detections of AH1pdm09 were sporadically reported in weeks 41-42 and 51-52 of 2011 and weeks 1, 3, 6, 7, 8, 11, 14, 15, 17 and 25 of 2012 (Fig. 1).
From week 36 (September 5-11) of 2011 to week 25 (June 18-24) of 2012, isolations/detections of AH1pdm09 from 14 cases in 10 of 47 prefectures, AH3 from 5,005 cases in all prefectures, B/Victoria lineage from 1,086 cases in 40 prefectures, B/Yamagata lineage from 541 cases in 39 prefectures and B/lineage not determined from 354 cases in 36 prefectures were reported (Fig. 2). |
 From week 21 (May 21-27) to week 25 (June 18-24) of 2012 (as of July 19, 2012) |
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During five weeks from week 21 to week 25 of 2012, isolations/detections of AH1pdm09 from a case in Ibaraki Prefecture, AH3 from 7 cases in 6 prefectures, B/Victoria lineage from 12 cases in 9 prefectures, B/Yamagata lineage from 4 cases in 4 prefectures and B/lineage not determined from 3 cases in 3 prefectures were reported (Fig. 3).
[Reference figure] Weekly cases of influenza and isolation/detection of influenza viruses from week 36 of 2008 to week 41 of 2011 |
| Infectious Agents Surveillance Report, Infectious Disease Surveillance Center, National Institute of Infectious Diseases |