Volume 16, Number 4—April 2010
Research
Use of Norovirus Genotype Profiles to Differentiate Origins of Foodborne Outbreaks
, Harry Vennema, Wilfrid van Pelt, David Lees, Hendriek Boshuizen, Kathleen Henshilwood, Marion Koopmans, on behalf of the Food-Borne Viruses in Europe Network1
Table 2
ρ1, ρ2, and Cramer V results with simulated p values (20,000 replications) of norovirus 6 genotype patterns as detected in routinely tested bivalve shellfish and during norovirus outbreaks, 1999–-2004*
| Source | FB-food (p value) | FB-feces (p value) | FHB (p value) | PB (p value) | UN (p value) | Bivalve mollusk (p value) |
|---|---|---|---|---|---|---|
| FB-food | ||||||
| ρ1 | 1.00 | 0.48 (0.02) | 0.40 (0.07) | 0.43 (0.04) | 0.48 (0.02) | 0.91 (<0.01) |
| ρ2 | 0.46 (0.03) | −0.15 (0.51) | 0.34 (0.12) | 0.24 (0.26) | 0.47 (0.03) | |
| Cramer V |
0.47 (0.01) |
0.62 (0.04) |
0.48 (<0.01) |
0.26 (<0.01) |
0.41 (0.02) |
|
| FB-feces | ||||||
| ρ1 | 1.00 | 0.93 (<0.01) | 0.92 (<0.01) | 0.96 (<0.01) | 0.53 (0.01) | |
| ρ2 | 0.40 (0.06) | 0.55 (<0.01) | 0.66 (<0.01) | 0.69 (<0.01) | ||
| Cramer V |
0.34 (0.41) |
0.43 (<0.01) |
0.19 (<0.01) |
0.57 (<0.01) |
||
| FHB | ||||||
| ρ1 | 1.00 | 0.97 (<0.01) | 0.93 (<0.01) | 0.43 (<0.05) | ||
| ρ2 | 0.22 (0.32) | 0.39 (0.07) | 0.47 (0.03) | |||
| Cramer V |
0.25 (<0.01) |
0.09 (0.75) |
0.46 (<0.01) |
|||
| PB | ||||||
| ρ1 | 1.00 | 0.96 (<0.01) | 0.51 (0.01) | |||
| ρ2 | 0.61 (<0.01) | 0.53 (0.01) | ||||
| Cramer V |
0.42 (<0.01) |
0.63 (0.01) |
||||
| UN | ||||||
| ρ1 | 1.00 | 0.59 (<0.01) | ||||
| ρ2 | 0.65 (<0.01) | |||||
| Cramer V |
0.48 (<0.01) |
|||||
| Bivalve mollusk | 1.00 |
*ρ1 = based on frequencies; ρ2 = based on logarithm of frequencies; Cramer V, χ2 test with simulated p values; FB-food, foodborne-food, i.e., an outbreak was reported to be caused by food and the outbreak strain was detected in food; FB-feces, foodborne-feces, i.e., an outbreak was reported to be caused by food and the outbreak strain was detected in human feces only; FHB, food handler–borne, i.e., an outbreak was reported to be caused by an infected food handler contaminating the food and the outbreak strain was detected in human feces; PB, person-borne, i.e., an outbreak was reported to be caused by person-to-person transmission and the outbreak; strain was detected in human feces; UN, unknown, i.e., the mode of transmission was not reported or was reported to be unknown and the outbreak strain was detected in human feces.
1Members of the Food-Borne Viruses in Europe Network: B. Böttiger, K. Mølbak, C. Johnsen (Denmark); K.-H. von Bonsdorff, L. Maunula, M. Kuusi (Finland); P. Pothier, K. Balay, J. Kaplon, G. Belliot, S. Le Guyader (France); E. Schreier, K. Stark, J. Koch, M. Höhne (Germany); G. Szücs, G. Reuter, K. Krisztalovics (Hungary); Ireland: M. Lynch, B. Foley, P. McKeown, S. Coughlan (Ireland); E. Duizer, A. Kroneman, Y. van Duynhoven (the Netherlands); K. Vainio, K. Nygard, G. Kapperud (Norway); M. Poljsak-Prijatelj, D. Barlic-Maganja, A. Hocevar Grom (Slovenia); F. Ruggeri, I. Di Bartolo (Italy); A Bosch, A. Dominguez, J. Buesa, A. Sanchez Fauquier, G. Hernández-Pezzi (Spain); K.-O. Hedlund, Y. Andersson, M. Thorhagen, M. Lysén, M. Hjertqvist (Sweden); D. Brown, B. Adak, J. Gray, J. Harris, M. Iturriza (United Kingdom).