Volume 22, Number 6—June 2016
CME ACTIVITY - Synopsis
Human Infection with Influenza A(H7N9) Virus during 3 Major Epidemic Waves, China, 2013–2015
Peng Wu1, Zhibin Peng1, Vicky J. Fang, Luzhao Feng, Tim K. Tsang, Hui Jiang, Eric H.Y. Lau, Juan Yang, Jiandong Zheng, Ying Qin, Qiao Sun, Gabriel M. Leung, Sheng Wei
, and Benjamin J. Cowling
, and Benjamin J. Cowling
Table 1
Characteristics of laboratory-confirmed influenza A(H7N9) cases detected in 3 epidemic waves, China, 2013–2015
| Characteristic | No. (%) cases |
|||
|---|---|---|---|---|
| Wave 1A, Jan 2013–Mar 2013, n = 19 | Wave 1B, Apr 2013–Sep 2013, n = 115 | Wave 2, Oct 2013–Sep 2014, n = 306 | Wave 3, Oct 2014–Mar 2015, n = 215 | |
| Age group, y | ||||
| 0–15 | 1 (5) | 6 (5) | 19 (6) | 17 (8) |
| 16–59 | 8 (42) | 47 (41) | 151 (49) | 113 (53) |
| 60–74 | 8 (42) | 37 (32) | 89 (29) | 58 (27) |
| >75 | 2 (11) | 25 (22) | 47 (15) | 27 (13) |
| Median |
60 |
61 |
57 |
56 |
| Male sex |
13 (68) |
81 (70) |
212 (69) |
154 (72) |
| Residence* | ||||
| Provincial capital or municipality | 10 (53) | 58 (50) | 57 (19) | 22 (10) |
| Other cities | 6 (32) | 23 (20) | 131 (43) | 100 (47) |
| Rural areas |
3 (16) |
34 (30) |
118 (39) |
93 (43) |
| Presence of ≥1 underlying medical condition† |
10 (53) |
42 (37) |
91 (30) |
64 (30) |
| Onset to hospital admission, d | ||||
| 0–2 | 2 (11) | 12 (10) | 41 (14) | 32 (18) |
| 3–6 | 8 (44) | 62 (54) | 151 (52) | 84 (46) |
| >7 |
8 (44) |
41 (36) |
96 (33) |
65 (36) |
| Poultry exposure | ||||
| Any exposure to poultry | 15 (79) | 91 (83) | 165 (81) | 116 (74) |
| Occupational exposure to live poultry | 1 (5) | 6 (5) | 21 (7) | 22 (10) |
| Visited live poultry market | 12 (63) | 62 (54) | 132 (61) | 105 (67) |
| Exposure to sick or dead poultry | 0 (0) | 3 (3) | 3 (1) | 7 (5) |
| Exposure to backyard poultry | 6 (35) | 48 (49) | 34 (20) | 4 (2) |
*For more information, see the online Technical Appendix (http://wwwnc.cdc.gov/EID/article/22/6/15-1752-Techapp1.pdf).
†Only underlying medical disorders associated with a high risk for influenza complications were counted here, including chronic respiratory disease, asthma, chronic cardiovascular disease, diabetes, chronic liver disease, chronic kidney disease, immunosuppressed status, and neuromuscular disorders.
1These authors contributed equally to this article.
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