Table 1. Number of reported cases of influenza-associated encephalopathy (fatal cases) by virus type in Japan, 2004–2010.

	2004–2005	2005–2006	2006–2007	2007–2008	2008–2009	2009–2010
Dominant virus of influenza epidemic	B, A (H3N2)	A (H3N2)	A (H3N2), B	A (H1N1)	A (H1N1), A (H3N2), B	A (H1N1) 2009
Peeking week of ILI	9 of 2005	4 of 2006	11 of 2007	5 of 2008	4 of 2009	48 of 2009
Peeking week of IAE	10 of 2005	3 of 2006	10 of 2007	8 of 2008	5 of 2009	47 of 2009
A*	19 (2)	50 (7)	30 (1)	28 (6)	42(6)	1§ (0)
B†	30 (6)	4 (1)	7 (0)	1 (0)	7 (0)	1 (0)
A (H1N1) 2009‡	…	…	…	…	…	322 (12)
Unknown	6 (2)	0	5 (1)	5 (0)	5 (1)	7 (0)
Total	55 (10)	54 (8)	42 (2)	34 (6)	54 (7)	331 (12)

ILI: influenza like illness.

IAE: influenza-associated encephalopathy.

^*Reported as influenza A from week 36, 2004 through week 27, 2009.

^†Reported as influenza B from week 36, 2004 through week 35, 2010.

^‡Reported as influenza A (H1N1) 2009 or influenza A from week 28, 2009 through week 35, 2010.

^§Reported as influenza A (H3N2) in week 24, 2010.