Characterizing LBM Contact Networks. As most disease events are not detected, two study areas were selected based on demographic features—the province with the highest human population density in northern Vietnam, Hanoi (29), and a rural province with a large poultry population, Bac Giang (30) (Fig. 1A). Live poultry traders were recruited in 30 LBMs (n = 561) as well as in a nonmarket site (n = 6) (Materials and Methods).