Volume 11, Number 1—January 2005
Research
Norovirus and Foodborne Disease, United States, 1991–2000
Table 3
Role of different foods and foodhandlers in outbreaks of gastroenteritis of noroviral, bacterial, and unknown cause, United States, 1998–2000*
Cause of outbreak |
p value† | |||
---|---|---|---|---|
Norovirus no. (%) | Bacteria no. (%) | Unknown no. (%) | ||
Total outbreaks with data on implicated food | 76 | 124 | 408 | |
Implicated food | ||||
Salad | 20 (26) | 20 (16) | 73 (18) | NS |
Sandwich | 10 (13) | 0 | 24 (6) | < 0.05‡ |
Produce/fruit | 13 (17) | 4 (3) | 15 (4) | < 0.001 |
Meat dish | 8 (11) | 50 (40) | 139 (34) | < 0.001 |
Fish dish | 4 (5) | 9 (7) | 19 (5) | NS |
Bakery product | 5 (7) | 2 (2) | 15 (4) | NS |
Oysters | 2 (3) | 2 (2) | 12 (3) | NS |
Other various§ |
14 (18) |
37 (30) |
111 (27) |
ND |
Total outbreaks with data on investigation of foodhandler | 94 | 102 | 564 | |
Foodhandler implicated | ||||
Yes | 45 (48) | 20 (20) | 51 (9) | < 0.001 |
No | 49 (52) | 82 (80) | 513 (91) |
* ND, not done; NS, not significant.
†Chi-square test: p value refers to comparison of norovirus (NoV) outbreaks with both bacteria and unknown outbreaks separately.
‡p < 0.001 when comparing NoV outbreaks with bacterial outbreaks.
§No difference noted for dairy products (3%–5%), cold meats (2%–4%), egg dishes (0%–1%), beverages (1%–4%), or ice (0%–1%).
1Efforts in 1998 to improve outbreak reporting resulted in more outbreaks being retrospectively attributed to this period. The current figures for 1993 to 1997 are 65 (2%) of 3,257 outbreaks attributable to NoV and 67% of unknown etiology.