Scientists have confirmed that the deadly H7N9 bird flu strain is transferrable between ferrets. Six of the animals — which often serve as a good measure for the risk of transmission between humans — were injected with the virus and placed in a cage with three uninfected ferrets. Three more uninfected specimens were nearby, but outside of the cage. All three caged ferrets became infected with H7N9, though only outside ferret was afflicted. That suggests there's less risk of infection by air compared with direct contact, but scientists warn the successful transfer rate is higher than many prior avian viruses. Worse yet, the National Institute of Allergy and Infectious Diseases-funded test further confirms that new carriers can appear asymptomatic for an entire day while spreading H7N9 to others. Don't start worrying about a pandemic just yet; the same test applied to pigs revealed that swine failed to transmit H7N9 through either contact or air exposure. Nonetheless, H7N9 has thus far killed 36 people and caused sickness in 131 individuals, though its spread appears to have slowed in recent days.