On a recent evening commute through Bunia, the capital of Ituri Province in the eastern Democratic Republic of Congo, the streets looked almost ordinary. This city of nearly 1 million people was teeming with life: fruit vendors lined the streets, the shops were crowded, and restaurants were filling for the evening.

But things are not normal at all. Ebola is ravaging the area and has killed more than 4,000 people countrywide, most of them in the Ituri province.

Indeed, it was hard to reconcile what I was seeing with what I’d heard from the driver who had taken me to visit a nearby health center. He told me that his brother and three members of his wife’s family had died of Ebola. His family knew about the disease, he said, but by the time they realized how sick they were, it was too late. They died at home, before making it to a hospital. Nearly half of all people who are confirmed to have Ebola will die from it.

I have worked in humanitarian health in this region for decades and helped lead responses to several Ebola outbreaks. I have never seen one get this far ahead of us. Even now, more than 140 days after the outbreak was declared, most new cases are appearing outside the chains of transmission that health workers are tracking, and between one-third and two-thirds of deaths are occurring not in treatment centers but in people’s homes and communities. The threat is spreading: Last week, Kenya reported its first Ebola case after a man who had traveled there from Congo died of the disease.