The recent Ebola outbreak highlights the serious threat that emerging infectious diseases can pose to global public health. Despite years of apparent preparations for a devastating pandemic, responses to outbreaks are cumbersome and delayed, and opportunities to save lives are missed. Over the past 15 years, the systematic failure to collect and share clinical data during epidemics, including zoonotic viruses such as SARS, H5N1, Nipah, and MERSCoV, has been a recurring problem. Understanding the inter-relationships between human behaviour, animal health and the environment is essential for mobilising successful responses to future spillover events. Professor Farrar is the Director of the Wellcome Trust.