Building healthy communities in urban Brazilian slums Urbanisation provides one of today's major public health challenges. In low income cities, infectious diseases, linked to contaminated water and food and limited sanitation, exist alongside increased risks of air and water pollution. Social violence is often epidemic. The young are amongst the most vulnerable but also often those with least voice in decisions about their future. The city of Salvador, Brazil, where this project is based, exemplifies these problems.   Financial constraints mean that there is an urgent need for sustainable, locally-developed interventions to improve multiple health outcomes in these settings, and in selecting interventions, we need a framework that targets the common drivers of poor health. Community-based mitigations must be based, also, on local knowledge of determinants of risk, and managed to ensure that they can be adapted to the local context.   Here, therefore, we adopt an approach based on adaptive management, through which an initial, evidence-based management plan, developed through consensus between experts and local stakeholders, is repeatedly re-assessed and, if appropriate, modified (adapted) in the light of additional evidence, collected on an on-going basis. Our aim is to enhance wellbeing in communities in Salvador, and provide a blueprint for similar projects in urban slums worldwide.   We will focus on the interacting effects of infectious diseases that represent three different transmission routes, and on interventions to mitigate their risk. 1) Leptospirosis and enteric (gut) infections, which are environmentally transmitted via rats, water and soil where sanitation is poor. 2) Zika, Dengue, and Chikungunya, caused by mosquito-borne pathogens whose risk is associated with mosquito infestation and reproduction. 3) Directly transmitted infections, including Tuberculosis whose transmission is predominantly domestic, and sexually transmitted infections including HIV. Interventions varying in purpose will be chosen from a range of possibilities on an evidence-based basis, by groups comprising the residents themselves, with a special focus on youths, facilitated by our team.   Work will be based in 3 urban slum communities where we have already collected and analyzed data on a range of communicable diseases, having established relationships with residents' groups, fully and enthusiastically committed to the program. We will evaluate changes in incidence rates for diseases before, during and after interventions, as well as data on multiple aspects of knowledge, attitudes and practices of residents, environmental data in public, peri-domestic, and domestic areas, the presence, extent and location of open sewers and trash accumulation, and relevant water/soil samples to quantify pathogen loads.  At the beginning of the project, in each community, a working group of residents and experts will be established, who will critically evaluate current findings to identify and guide acquisition of additional data required to choose interventions. Thus, over the first year, each community will use the previously- and newly-collected data as a basis for defining key interventions and relevant metrics to evaluate the interventions. Further pre-intervention metrics will be collected during the second 6 months.  Then, at the end of the first year, community-specific interventions will be implemented - either environmental (eg closing sewers) or behavioural (eg improving access to health visitors), following which further data will be collected. After a further 9 months, the management groups will undertake an evidence-based assessment of the interventions' effectiveness, reflecting on the outcomes. This will lead to a re-considered, modified, set of interventions (or a decision to maintain the status quo), followed by further data collection, and ultimately to a full assessment of both the interventions, and of the processes that led to their initial genesis and subsequent adaptation. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.