Two separate groups have been using ferrets to investigate how harmful A(H1N1) influenza virus is and how easily it is transmitted. One of the studies was by Terrence Tumpey at the Centers for Disease Control and Prevention in Atlanta, Georgia, and his colleagues, and is published in Science1. Tumpey's team put droplets of three different swine flu viruses, and one 'seasonal' flu virus into the noses of ferrets. Some ferrets shared cages with other uninfected ferrets and some were placed in cages next to other ferrets, sharing nothing but the air they breathed.The experiments showed that the ferrets with swine flu strains lost more weight than those with normal flu, and that the swine flu reached lower down into the lungs of some of the ferrets than normal seasonal flu, penetrating the intestines in some cases. This tallies with observations in humans that some patients suffered vomiting and diarrhoea. A second study by Ron Fouchier at the Erasmus University Medical Center, Rotterdam, the Netherlands, and his colleagues also showed that the virus penetrated the lungs. "This is the first indication of how pathogenic [swine flu] really is," says Fouchier. "In the field that conclusion is hard to draw."
