ANURADHAPURA — More than 20,000 farmers in Sri Lanka, mostly rice farmers in the north, have lost their lives in recent years because of an unexplained surge in kidney disease. It has now reached epidemic proportions, and patients are descending on overwhelmed clinics, lining up for the few dialysis machines available.

Karnu Jemanta and his brother, who are working their rice field outside the village of Rambewa, are worried. "We're not sick yet, but we may be soon," Jemanta says. "People from the Health Ministry came and said it could be chemicals, or that we should drink more water when we're working. We're doing what they've told us to do."

In his small house near the Rambewa village, 74-year-old Puntibanda is stretched out on his bed, desperately ill and in the last stages of kidney failure. "Four of my farmer friends are in the same condition as me," he says. "We all drank water from the canals or directly from the fields when we had to. The doctor said I'm dying of kidney failure, but he couldn't say why."

At the kidney unit of the Anuradhapura provincial hospital, it's clear just how devastating the epidemic has become. More than 100 people are waiting for kidney examinations today. The estimated number of those affected is 400,000, according to the Sri Lankan Health Ministry.

"I would say it was first noticed some 15 to 20 years back," explains nephrologist Rajeewa Dissanayake. "They looked into it in detail and found that there were lots of patients with kidney disease here." He says a screening program has helped to identify those affected. "So far I think about 150,000 have been screened, and a number of them have been detected and have been treated." But, he says, "We don't know what the cause is, so it's difficult to prevent."

Channa Jajasumana, a medical faculty member at Rajarata University, says more research is needed. He's been studying Sri Lanka's rampant kidney disease for the last 10 years and says there are two important questions that need to be answered: "Why has this epidemic come after the mid-1990s? And what is the reason for this unique geographical distribution?"

On his computer screen, Jajasumana displays a map of Sri Lanka where the districts that are most affected are highlighted. He points to a clear area where there is no disease. "You will see that this disease is confined to certain regions of the dry zone in Sri Lanka — but not in the northern peninsula," he says. "There, the climate is quite hot compared to Anuradhapura, but there's no disease. What could be the reason?"

Are agrochemicals to blame?

He speculates that the explanation has to do with terrorism over the last 30 years, and the fact that the Sri Lankan government didn't allow agrochemicals to be sent to that area. "The people in the northern area have not used those chemical because terrorists used these fertilizers to produce explosives."

But so far this theory hasn’t been substantiated with hard, empirical evidence. What is certain is that 80% of those affected are poor rice farmers.

The World Health Organization released a 2013 study regarding the Sri Lankan kidney disease epidemic, and it points to several possible causes: low levels of cadmium and other heavy metals, the presence of pesticides, and dehydration and genetic factors among the farmers.

Curiously, there is a similar ongoing epidemic in Latin America. Research being conducted there by a Swedish team of researchers and led by kidney specialist C.G. Elinder points to chronic dehydration as a major factor.

In Latin America, it’s sugar cane workers who are being taken ill. "We've done specialized examinations on patients, and we've seen that their kidneys don't have the typical appearance of those affected by chemicals, which usually bear marks of inflammation," Elinder says. "What we see is kidneys that are affected by lack of oxygen. That can mean that they are suffering from chronic dehydration and loss of electrolytes."

In the hot climate, cutting sugar cane all day and not drinking enough fluids can cause chronic damage to the kidneys, Elinder says. But specialists don’t know if the underlying cause is the same in both Latin America and in Sri Lanka. In a few months, the Swedish and Sri Lankan research teams will meet in northern Sri Lanka to conduct more studies.

Despite thousands of deaths related to kidney disease on several continents, it's difficult to find sufficient funding for research, says Annika Werneson, a pathologist with the Swedish research team. She's frustrated that the disease hasn't been given the attention it deserves from more developed countries. "If this epidemic had happened in Europe, we'd certainly have found plenty of research money."