Table 1.
Characteristics of Primary and Secondary Cases, Kaiser Permanente Northwest, April 2014–September 2016
| Cases, Median (Range) or No. (%) | ||
|---|---|---|
| Characteristic | Primary (n = 570) | Secondary (n = 338)a |
| Age, y | 7 (0–96) | 28 (0–89) |
| Symptom duration, d | 5 (0–30) | 4 (1–32) |
| Age group, y | ||
| 0–4 | 244 (43) | 53 (16) |
| 5–17 | 82 (14) | 61 (18) |
| 18–64 | 151 (26) | 206 (61) |
| ≥65 | 93 (16) | 18 (5) |
| Gender: male | 301 (53) | 180 (53) |
| Race | ||
| White | 427 (75) | 81 (85) |
| Black | 14 (2) | 3 (3) |
| Asian | 22 (4) | 4 (4) |
| Multiple races specified | 53 (9) | 2 (2) |
| Other | 37 (7) | 4 (4) |
| Unknown | 4 (1) | 1 (1) |
| Refused | 2 (0.3) | 0 (0) |
| Hispanic ethnicity | 88 (15) | 7 (8) |
| Education of primary caseb | ||
| Less than high school | 7 (3) | 2 (4) |
| High school equivalent | 60 (25) | 7 (14) |
| Some college | 82 (34) | 14 (27) |
| College graduate | 93 (38) | 28 (55) |
| Don’t know | 1 (0.4) | 0 |
| Refused | 1 (0.4) | 0 |
| Symptomc | ||
| Diarrhea | 539 (95) | 81 (85) |
| Vomiting | 423 (74) | 74 (78) |
| Fever | 271 (48) | 36 (38) |
| Headache | 249 (44) | 49 (52) |
| Muscle ache | 235 (41) | 58 (61) |
| Abdominal pain | 425 (75) | 77 (76) |
| Lethargy | 472 (83) | 80 (84) |
| Chills | 250 (44) | 38 (40) |
| Nausea | 450 (79) | 79 (83) |
| Bloody stool | 15 (3) | 4 (4) |
| Exposure characteristicsd | ||
| Travel outside US | 17 (3) | 4 (4) |
| Dine at a restaurant/fast food/vendor | 402 (71) | 66 (69) |
| Consume food at potluck/event | 172 (30) | 24 (25) |
| Contact with | ||
| Diapered children/adult | 289 (51) | 76 (81) |
| Children in day care/nursery | 240 (43) | 54 (57) |
| Person at nursing home | 43 (8) | 2 (2) |
aData available only for 102 secondary cases. Age and gender information available for all secondary cases.
bEducation information available for individuals aged >18 years: primary cases, n = 259; secondary, cases, n = 55.
cSymptoms are not mutually exclusive.
dIn the 7 days prior to symptom onset.