Figure 1.

Clinical score and survival rate of the target group (seropositive Pekin ducks; B1; B2) and the control group (seronegative Pekin ducks; B1; B2). Of the 7 mallards, only 2 ducks appeared depressed for 2–3 days, but one died, while 3 of 4 contact ducklings died until 4 days post contact. In the seronegative Pekin duck group, all 7 ducks, including all 4 contact ducklings, developed severe clinical disease and died within 9 days post infection/contact. Three birds that were humanely killed were registered as “3” (dead) the day after.