While H5N1 avian influenza virus taken from infected cow's milk makes mice and ferrets sick when dripped into their noses, airborne transmission of the virus between ferrets -- a common model for human transmission -- appears to be limited. These and other new findings about the strain of H5N1 circulating among North American dairy cattle this year come from a set of laboratory experiments. Together, they suggest that exposure to raw milk infected with the currently circulating virus poses a real risk of infecting humans, but that the virus may not spread very far or quickly to others.
