Chronic kidney disease affects one in 10 adults worldwide, and in more prosperous countries, it’s often associated with diseases such as diabetes or hypertension. But in the past few decades, young people—primarily agricultural workers from very hot, rural, poor parts of the world—have been showing up at clinics with advanced stages of kidney failure that could not be tied to other conditions.

In places such as Sri Lanka, Nicaragua, Peru, and India, chronic kidney disease from undetermined causes (CKDu) is killing thousands of people each year—and its incidence is increasing faster than any other disease besides HIV.

Photographer and filmmaker Ed Kashi has spent the last five years documenting the effects of CKDu around the world. In