Volume 13, Number 3—March 2007
Research
Surveillance of Influenza Virus A in Migratory Waterfowl in Northern Europe
Table 4
Comparison of multiyear influenza A virus screening studies of ducks in North America (2), Germany (16) and Sweden (present study)*
| Study region | Sweden | Germany | North America |
|---|---|---|---|
| Prevalence during fall | 15.0% (in mallards) | 8.7% | 22.2% |
| Prevalence during spring | 4.0% (in mallards) | No data | 0.03% |
| Most prevalent HA subtypes | H4, H6, H7 | H4, H2, H1, H6, H7 | H6, H3, H4 |
| HA subtypes not found | H9, H13–16 | H5, H12–16 | H13–16 |
| Most prevalent NA subtypes | N2, N6, N7 | N1, N3, N6 | N8, N2, N6 |
| NA subtypes found | N1–9 | N1–9 | N1–9 |
| Most prevalent subtype combinations | H4N6, H7N7, H6N2 | H2N3, H4N6, H1N1, H6N2, H7N7 | H3N8, H6N2, H4N6 |
*HA, hemagglutinin; NA,neuraminidase.


