Editor’s note — 4/16/12: In the past 24 hours, our Kickstarter project has officially exceeded our goal of $7,500. Many thanks to everyone who pledged their support. We'll have more details on the investigation's next steps soon. 

A deadly disease is killing thousands of the world's poorest laborers — and no one knows what is causing it. Last December, reporter Sasha Chavkin and the Center for Public Integrity published an investigation about this deadly mystery, chronic kidney disease.

In the United States, chronic kidney disease is a manageable illness that mostly affects older people with diabetes and high blood pressure. But in Central America, each year thousands of agricultural laborers — almost all men, lacking the usual risk factors, and as young as their 20s — are dying of a new strain of chronic kidney disease that has baffled scientists for more than a decade. The disease has so decimated one community of sugarcane workers in Nicaragua called La Isla, or The Island, that it is now known to locals is La Isla de las Viudas — The Island of the Widows.

That first story about the epidemic prompted the Costa Rican government to launch a study and a leading Costa Rica plantation to announce an overhaul of its worker safety practices. Photographer Anna Maria Barry-Jester produced an award-winning photo gallery on the Island of the Widows that shows the day-to-day routines of a community where an incredible 40 percent of the working-age population suffers from the disease.

The Costa Rican government has launched a study into the causes of chronic kidney disease in its sugarcane producing northern region. At the same time one of the country’s biggest sugar producers said it is revamping its worker health and safety policies.

The steps follow an investigation by the International Consortium of Investigative Journalists that explored the mysterious and largely overlooked epidemic of chronic kidney disease — or CKD — that is killing thousands of sugarcane workers and other manual laborers in Central America.

The Costa Rica study will seek to answer one of the thorniest and most politically sensitive questions surrounding what regional health experts call an epidemic: whether the illness should be classified as an occupational disease. Many workers believe the malady is caused by pesticide exposure and working conditions. They have demanded compensation from the sugar industry, which has vehemently denied responsibility.

“The main objective is to test whether CKD is or is not a labor-related exposure,” said Dr. Roy Wong, an epidemiologist with Costa Rica’s national health service and lead investigator for the study.

The cause of the disease’s outbreak remains unknown, although a growing body of research has shown links between declining kidney function and repeated heat stress and dehydration — the result of strenuous labor in hot climates.

Thousands of men working in the Pacific Coast sugarcane fields of El Salvador, Nicaragua, Costa Rica and neighboring countries have been dying of chronic kidney disease, an ailment that in most parts of the developed world is a manageable condition. The condition has been exacerbated by difficult working conditions and poor access to timely health care, while Central American governments and the sugar industry have done little in response.

Over the years the number of cases of CKD has grown — so much that one community near sugarcane fields in Nicaragua, called La Isla, or The Island, is now known locally as the Island of the Widows. From 2005 to 2009, CKD claimed more than 2,800 men each year in the region; in El Salvador it is now the second-leading cause of death among adult men.

This was the phenomenon — widespread illness and death among a specific group of mostly men — that journalist Sasha Chavkin saw on a number of trips to the region over the past two years. Chavkin returned to the region on behalf of the International Consortium of Investigative Journalists, a project of the Center for Public Integrity, to interview dozens of current and former sugarcane field workers and their families and physicians, as well as researchers in the region. Reporting from Washington, D.C., Ronnie Greene, a senior reporter at the Center, joined Chavkin in pursuing answers and data from government health officials in a position to push for more action on CKD, global health officials and sugar industry representatives.

The reporters wanted to know: Why does it strike mostly men who mostly work in sugarcane fields? What triggers it? Why are so many people dying? What have wealthier nations and NGOs done to help?

Our analysis of the toll from chronic kidney disease (CKD) in Central America is based on mortality data from the World Health Organization. Our goal was to obtain to a conservative estimate of the epidemic’s impact in the region, despite the lack of formal recognition or classification for the new strain of the disease.

We used data for each of the countries where scientific studies and our interviews and observations indicated the ailment was present: Nicaragua, El Salvador, Costa Rica and Guatemala. Studies have indicated the disease is spreading in Honduras and Mexico as well. No data were available for Honduras, and while one study has shown CKD to be present in two communities in southern Mexico, there was no way of isolating the relatively small region that is affected.

Our statistics are drawn from several diagnostic categories from the International Classifications of Disease (ICD-10) that indicate kidney failure. This is partly because the lack of a distinct category for the epidemic resulted in kidney disease deaths being classified in different ways. It is also because prior to 2000, the World Health Organization presented data in only a single category that indicated overall deaths caused by kidney failure. To track changes over time and maintain a consistent approach, we applied the same formula to the newer data.

Two WHO doctors, Dr. Enrique Perez-Flores and Dr. Mario Melendez Montano, helped shape our analysis of these data. Both emphasized the degree to which it was likely to undercount the data due to poor recordkeeping and lack of recognition of CKD in the region. Perez-Flores agreed that changes in male deaths from kidney failure over time were a reasonable method for tracking the epidemic’s course in the absence of official recognition for it.