FIG. 3.

Virus titers in ducks experimentally infected with Gs/HK/739.2/02, in contact ducks, and in the drinking water provided for the ducks. Values plotted are the mean virus titers of all live birds on the indicated day (see Table 4). For calculation of the mean, influenza virus-positive samples with a virus titer of <1 log₁₀ EID₅₀/ml were assigned a value of 0.5 log₁₀ EID₅₀/ml. Index ducks (n = 3) were inoculated with 2 × 10^7.75 EID₅₀ of virus, and uninoculated contact ducks (n = 3) shared their cage, food, and drinking water.