SANDAMALGAMA, Sri Lanka -- In this tiny Sri Lankan village, rice farmer Wimal Rajaratna sits cross-legged on a wooden bed, peering out toward lush palm trees that surround his home. Listless and weak, the 46-year old father of two anxiously awaits word on whether his body can accept a kidney donation that offers his only chance of survival.
In Uddanam, India, a reed-thin farmer named Laxmi Narayna prepares for the grueling two-day journey he takes twice every week. For most of his 46 years, his job involved shimmying up palm trees to harvest coconuts at the top. He now spends most of his time negotiating the more than 100-mile bus trips he takes to receive the dialysis treatments that keep him alive.
Ten thousand miles away, in the Nicaraguan community of La Isla, Maudiel Martinez dreads returning to the rolling sugarcane fields where he spent most of his teenage years at work with a machete. Blood tests by the sugar company that employed him found that his kidneys were seriously damaged -- and exertion beneath the tropical sun could tip the 20-year-old's health into a lethal spiral.
In three countries on opposite ends of the world, these men face the same deadly mystery: their kidneys are failing, and no one knows why.
A mysterious form of chronic kidney disease -- CKD -- is afflicting thousands of people in rural, agricultural communities in Sri Lanka, India and Central America. The struggle to identify its causes is baffling researchers across multiple continents and posing a lethal puzzle worthy of Sherlock Holmes.
The three epidemics have crucial threads in common. The victims are relatively young and mostly farm workers, and few suffer from diabetes and high blood pressure, the usual risk factors for renal disease. They experience a rare form of kidney damage, known as tubulo-interstitial disease, consistent with severe dehydration and toxic poisoning.
Other common links offer clues to a possible cause. The epidemics affect sharply defined geographic areas that are stunningly fertile and swelteringly hot. The victims mostly perform heavy manual labor, have little formal education and lack easy access to medical care. Pesticides are used heavily, and communities drink local groundwater. In each case, the disease began surging in the 1990s.
Despite a decade of research in each affected region -- and a potentially noteworthy discovery this year in Sri Lanka -- scientists have yet to prove a chemical at fault or a means of exposure. Researchers are convinced that if they could identify the culprit, the outbreaks could be stopped and the death toll reversed.
"I absolutely think that it's preventable," said Daniel Brooks, an epidemiologist at Boston University who is leading a study in Nicaragua of the new form of CKD. "I'm very convinced that what is happening to individuals is from some sort of exposure."
In a sense, researchers are waging a race against three parallel epidemics occurring across multiple continents. Yet the search for clues was slow to begin, with governments including the United States moving with little urgency despite warnings of the disease's toll. And separate groups of researchers -- each chasing clues to kidney epidemics across the globe -- have not fully explored whether they are linked together.
The new form of CKD is not officially recognized in the Americas even though kidney disease has killed more people in El Salvador and Nicaragua than diabetes, HIV/AIDS and leukemia combined in the last five years on record, the Center for Public Integrity found.
In a disease not yet formally recognized, researchers cannot say how many have fallen ill. But the death toll reaches tens of thousands.
More than 16,000 men died of kidney failure in Central America from 2005 to 2009, with annual deaths increasing more than threefold since 1990, according to an analysis of World Health Organization data. In Sri Lanka, the WHO says at least 8,000 people suffer from chronic kidney disease of unknown cause, though other sources put the number more than double that. In the Indian state of Andhra Pradesh, more than 1,500 have been treated for the ailment since 2007.
"There's a need to connect all the dots between these different outbreaks," said Dr. Ajay Singh, a nephrologist at Harvard Medical School who is leading a study of the epidemic in India. "Our premise should be to first look for common causes."
The response has been fragmented in part because wealthy countries and international institutions have been reluctant to recognize the problem. Most CKD is caused by diabetes, obesity or hypertension, all fast-growing problems in the developing world. Health officials have sometimes blamed the usual suspects of unhealthy diet and lifestyles for any increase in CKD in poor countries -- a diagnosis that neglects the possibility of environmental exposure.
"Nephrologists and public health professionals from wealthy countries are mostly either unfamiliar with the problem or skeptical whether it even exists," said Dr. Catharina Wesseling, the regional director for the Program on Work and Health (SALTRA) in Central America, which pioneered the initial studies of the region's unsolved outbreak. "The response from the North and from international agencies must be much stronger."
In the meantime, thousands of villagers are dying each year from an ailment triggering as many questions as answers. Are tainted agrochemicals to blame? Dehydration in the fields, aggravated by dangerous working conditions? Or could multiple culprits exist, with different causes in each region?
From Sri Lanka to India to Central America, all the victims know is that something in their lush, hauntingly beautiful surroundings is wasting away their lives. In one patch of rural Nicaragua, so many men have died the community is called "The Island of the Widows." In the Indian region of Uddanam, a reverse trend has taken hold: Couples decline to marry at all.