Why we should care? Because if we don’t know what kills people, how are we meant to stop it?When we think about hazards to our health, stuff like Ebola and swine flu inevitably come to mind. Didja know the bubonic plague has been making cameo appearances? (We’re looking at you, Arizona.) Sure, the horror-film scares are more frightening than boring old heart disease, and plague-level diseases hog all the headlines. But there’s a global health crisis you’ve never heard of. Yes, yes — gather your children close!A massive four-part series of studies conducted by leading epidemiologists shed some light on an underappreciated global health crises. They found2/3 deaths across world go unrecorded.That means we don’t know how some 40 million people die per year. “Policy is very weak because countries don’t have any evidence” for what’s killing populations, says Alan Lopez, one of the studies’ lead authors and laureate professor at the University of Melbourne’s school of population and global health. Without a cause of death and other basic demographic information, aka civil registration and vital statistics, it makes trying to prevent premature death a Goliath task. The series of studies, published in The Lancet, also found that another 40 million births a year, approximately one-third of the world’s total, also go unrecorded.So how do governments, nongovernmental organizations and international institutions like the World Health Organization get their death stats? Instead of doctors pronouncing patients dead and filling out forms on the spot — like in the U.S., for example — causes of death are often determined by surveys or censuses, which are usually conducted by data collectors going door to door. Folks are asked every few years about who died and when, but not about all the necessary ingredients to determine how they died, like medical history and symptoms. It’s one of the reasons why tobacco and pollution aren’t as strictly regulated in the developing world — there’s no official number of deaths that civil society can put in the face of politicians to kick-start change, says Alessandro Demaio, a visiting fellow in global health and social medicine at Harvard Medical School and co-founder of NCDFree.