SARS. Flu. MERS. Ebola. Zika. Those are just five diseases that have caused major epidemics since the start of this century. There's no doubt that many others will follow. Not so long ago, it looked like the advent of vaccines and antibiotics, might rid humanity of infectious diseases altogether. But ecological upheaval, burgeoning travel and trade, a changing climate, and failures in public health systems have allowed new pathogens to emerge and old ones to bounce back. Meanwhile, antibiotic resistances have become a worldwide emergency, and inequity in the global health system means that many people still don't have access to the vaccines, medicines and diagnostics that could save their lives. On this page, we keep track of what a wide variety of pathogens are up to--and how scientists are trying to stay ahead of them.