Volume 23, Number 8—August 2017
Dispatch
Preliminary Epidemiology of Human Infections with Highly Pathogenic Avian Influenza A(H7N9) Virus, China, 2017
Table
Selected characteristics of case-patients with HPAI and LPAI A(H7N9) virus infections, mainland China, September 1, 2016–March 31, 2017*
| Characteristics |
Infection type |
p value |
|
|---|---|---|---|
| HPAI, n = 8 |
LPAI, n = 553 |
||
| Median age (range), y |
56.5 (28–71) |
57 (3–91) |
0.632† |
| Age group, y | |||
| 0–14 | 0 | 5/553 (1) | NA |
| 15–59 | 5 (63) | 313/553 (57) | – |
| >60 |
3 (38) |
235/553 (42) |
– |
| Sex | |||
| M | 4 (50) | 400/553 (72) | 0.317 |
| F |
4 (50) |
153/553 (28) |
– |
| Residence area‡ | |||
| Urban | 1 (13) | 193/364 (53) | 0.031§ |
| Rural |
7 (88) |
171/364 (47) |
– |
| Having >1 underlying medical conditions¶ |
5 (63) |
234/432 (54) |
0.733# |
| Poultry exposure within 10 d of illness onset | |||
| Any exposure to poultry | 8 (100) | 442/500 (90) | 1.000§ |
| Visited live poultry market | 3 (38) | 324/442 (73) | NA |
| Exposure to backyard poultry | 4 (50) | 98/442 (22) | NA |
| Occupational exposure to poultry | 1 (13) | 20/442 (5) | NA |
| Exposure to sick or dead poultry |
4 (50) |
43/268 (16) |
0.037# |
| Clinical management | |||
| Hospitalization | 8 (100) | 478/480 (99) | NA |
| Antiviral treatment | 8 (100) | 392/404 (97) | NA |
| ICU | 7 (88) | 323/403 (80) | 1.000 |
| Mechanical ventilation |
6 (75) |
221/386 (57) |
0.476 |
| Timeline of clinical management (median), d† | |||
| Illness onset to first medical service seeking | 0.5 (0–5) | 2 (0–34) | 0.096 |
| Illness onset to hospitalization | 2.5 (0–5) | 5 (0–35) | 0.032 |
| Illness onset to antiviral treatment | 4 (1–8) | 6 (0–29) | 0.168 |
| Illness onset to diagnosis | 6.5 (4–9) | 8 (0–31) | 0.241 |
| Illness onset to death |
6.5 (5–44) |
13 (2–62) |
0.180 |
| Outcome | |||
| Death | 4 (50) | 203/376 (54) | 1.000 |
| Recovered and discharged | 4 (50) | 173/376 (46) | – |
*Values are no. (%) unless otherwise indicated. The χ2 test was used to compare the variables between HPAI and LPAI groups. Data were missing for some variables, and data on final outcomes were missing for case-patients with LPAI A(H7N9) virus infection who remained hospitalized as of March 31, 2017. We were not able to perform the statistical analyses to assess differences for some variables because the number of cells with expected frequency of <5 was >20% and some cells had expected frequency of <1. HPAI, highly pathogenic avian influenza; ICU, intensive-care unit; LPAI, low pathogenic avian influenza; NA, not available.
†The z-test was used to compare median age and median days of the timeline of clinical management between HPAI and LPAI groups.
‡Urban was defined as cities, towns, and suburbs; rural was defined as villages and countryside (3).
§Residence area and “any exposure to poultry” were compared between HPAI and LPAI groups by using the Fisher exact test.
¶Three HPAI case-patients had chronic cardiovascular disease, and 2 HPAI case-patients had chronic metabolic disease.
#“Having >1 underlying medical conditions” and “exposure to sick or dead poultry” were compared between HPAI and LPAI groups by using the χ2 test for continuous correction.
1These authors contributed equally to this article.