Volume 19, Number 8—August 2013
Dispatch
Norovirus Surveillance among Callers to Foodborne Illness Complaint Hotline, Minnesota, USA, 2011–2013
, Dawn Kaehler, Elizabeth A. Cebelinski, Brian Nefzger, Aron J. Hall, and Kirk E. Smith
Table 1
Demographics, signs and symptoms, and epidemiologic characteristics for callers to foodborne illness hotline, Minnesota, USA, October 2011–January 2013*
| Characteristic | All symptom-eligible complainants |
Complainants tested for norovirus |
|||||
|---|---|---|---|---|---|---|---|
| Tested, n = 241 | Not tested,† n = 700 | p value‡ | Positive, n = 127 | Negative, n = 114 | p value‡ | ||
| Age, y (range) | 44 (0–88) | 43 (1–91) | 0.62 | 44 (1–88) | 44 (0–88) | 0.49 | |
| Duration, h (range) | 30.80 (0.25–205.30) | 29.0 (0.1–302.0) | 0.63 | 36.0 (9.5–121.0) | 18.00 (0.25–205.30) | 0.002 | |
| Female sex | 138 (57.3) | 405 (58.1) | 0.82 | 71 (55.9) | 67 (58.8) | 0.65 | |
| Signs and symptoms | |||||||
| Diarrhea | 193 (81.4) | 521 (81.0) | 0.30 | 103 (83.0) | 90 (79.6) | 0.50 | |
| Vomiting | 183 (76.3) | 513 (74.0) | 0.50 | 110 (87.3) | 73 (64.0) | <0.001 | |
| Bloody stools | 9 (4.5) | 23 (4.3) | 0.94 | 2 (2.0) | 7 (7.0) | 0.09 | |
| Fever | 81 (45.0) | 152 (30.6) | <0.001 | 46 (52.9) | 35 (37.6) | 0.04 | |
| Onset during norovirus season§ | 172 (71.4) | 486 (69.4) | 0.57 | 108 (85.0) | 64 (56.1) | <0.001 | |
| Health care visit | 14 (6.5) | 91 (13.5) | 0.006 | 6 (5.6) | 8 (7.5) | 0.58 | |
| Outbreak associated¶ | 30 (12.4) | 53 (7.6) | – | 24 (18.9) | 6 (5.3) | – | |
*Values are no. (%) except as indicated. Symptom-eligible complainants were callers who reported diarrhea (>3 loose stools in 24 h) or vomiting. Denominators vary because of missing data. Boldface indicates significance.
†Includes all complainants eligible to submit a sample on the basis of symptom profile alone (symptom eligibility) as well as complainants not eligible to submit a stool sample for testing based on other eligibility criteria.
‡χ2 test was used for categorical variables; Fisher exact test used when expected cell frequencies were <5; Wilcoxon 2-sample test was used for comparison of medians.
§Season defined as October–March.
¶One complainant per outbreak identified through the hotline was included in analyses, if otherwise eligible.