Highly pathogenic avian influenza virus subtype H5N1 (HPAIV H5N1) is endemic in South-East Asia, with live bird trade as a major pathway for disease transmission. A cross-sectional survey was undertaken in northern Vietnam to investigate the structure of the live bird market (LBM) contact network, and the implications on the spread of HPAIV H5N1. A total of 567 traders were interviewed. Based on the movement of those traders between LBMs, weighted and directed static networks were constructed. The northern Vietnamese network incorporated 162 LBMs, of which 83% were encompassed in a giant strong component. Two provincial-level networks were also constructed. The removal of a small number of hubs (1-3 hubs, depending on the network) dramatically disconnected each network. A stochastic individual-based model was used to simulate the spread of HPAIV H5N1 through one of the provincial-level LBM networks. Degree appeared to be a good predictor of LBM infectiousness and susceptibility. LBMs exhibiting high susceptibility or infectiousness were always the same, regardless of transmission rate. This suggests that LBMs suitable for surveillance and control interventions could be effectively targeted without prior knowledge of the force of infection, which requires laboratory-confirmed surveillance. By targeting thorough, daily disinfection of LBMs and traders' vehicles and equipment to only the small number of markets acting as network hubs, the epidemic size was reduced by 80%. Disease spread within the network could therefore be effectively contained. These findings are of particular relevance to resource-scarce settings with extensively developed LBM systems, commonly found in South-East Asia. (Texte intégral)