Direct contact transmissibility of H5N6 influenza viruses of wild bird origin among chickens. Viral titers of ZH283 and SW8 in oropharyngeal swabs (A) and cloacal swabs (B) in H5N6 influenza virus-inoculated and physical contact chickens. Three chickens were inoculated intranasally with 105 EID50 of SW8 or ZH283, whereas three naïve chickens were placed in the cage of H5N6-infected chickens at 24 h post-infection to initiate contact. Oropharyngeal and cloacal swabs were collected from infected and naïve contact chickens at indicated time points; virus titers were titrated and are expressed as log10EID50/0.1 mL. Data are expressed as M ± SD. The proportion of chicken swabs presenting infectious virus from all detected swabs at indicated time points appears in the figure above each group. Dashed black lines indicate the lower limit of detection.