Therefore, this paper treats environmental sanitation separately because of the importance of the excreta management of humans and animals. Integrated syndromic surveillance and antimicrobial resistance surveillance link the above aspects and are showcases for a ‘One Health’ approach to biological threat reduction. Biological threats are not only related to natural conditions but may also be exacerbated by large development projects such as dams, mining and infrastructure. Consequently, it is recommended that the health impact assessment (HIA) approach be implemented as early as the planning stage of any large infrastructure project located in a complex socioecological system. This paper extends the HIA approach to an integrated ‘One Health’ impact assessment approach.