Table. Characteristics of cases referred to CDC for assessment of H5N1 infection*.
| Case-patient characteristics (n = 59) | No. (%) |
|---|---|
| Met CDC suspect H5N1 case definition | 27 (46) |
| Met hospitalized case definition criteria | 14 (24) |
| Met ambulatory case definition criteria | 13 (22) |
| Bird proximity <1 m | 14 (24) |
| Direct bird contact | 0 |
| Contact with confirmed human H5N1 case | 0 |
| Onset outside US influenza season | 7 (12) |
| Outcome | |
| Hospitalized | 20 (34) |
| Deceased | 4 (7) |
| Diagnosis† | |
| No | 28 (47) |
| Negative influenza test result but ILI and influenza A (H3)–positive contact | 8 (14) |
| Human influenza A (H3) | 23 (39) |
| Human influenza A (H1N1) | 1 (2) |
| Human Influenza A by rapid antigen test‡ | 1 (2) |
| Community-acquired pneumonia | 2 (3) |
| Bronchiolitis obliterans and organizing pneumonia | 1 (2) |
| Lymphoma | 1 (2) |
| Rickettsial typhus | 1 (2) |
| Toxic shock syndrome | 1 (2) |
| Country visited§¶ | |
| People’s Republic of China | 21 (36) |
| Vietnam | 18 (31) |
| Thailand | 11 (19) |
| South Korea | 5 (8) |
| Taiwan | 3 (5) |
| Cambodia | 2 (3) |
| Other# | 6 (10) |
| No foreign travel | 4 (7) |
| Unknown travel history | 2 (3) |
*CDC, Centers for Disease Control and Prevention; ILI, influenzalike illness. †Sum of percentages >100% due to rounding. ‡Clinical diagnosis of human influenza. The patient was reported to CDC for suspected H5N1 virus infection but was determined to lack risk factors to warrant H5N1-specific testing. §Not mutually exclusive. ¶As of June 15, 2006, highly pathogenic avian influenza A H5N1 has not been confirmed by the World Health Organization or World Organization for Animal Health (OIE) in Saipan, Saudi Arabia, Singapore, and Taiwan (1). Japan was declared free of H5N1 by OIE on July 12, 2004 (1), 13 mo before the visit by a reported patient. South Korea was declared free of H5N1 (1) at the time of a visit by a reported patient. #One each for Indonesia, Japan, Malaysia, Saipan, Singapore, and Saudi Arabia.