Kumaradasa, a Sri Lankan farmer suffering from a deadly kidney disease, bathes with the help of his wife in 2013 in Medavachchiya, Sri Lanka. Kumaradasa died on June 8. Eranga Jayawardena / Associated Press

Experts fail to find cause of disease that affects single province

It is midmorning, and hundreds of people are squeezed under a banyan tree's shady canopy to have blood drawn by just three nurses who are working assembly-line fast. Others wait outside this dusty rural health center to get their vitals taken and give urine samples.

Most of the 1,000 villagers have come on foot and have stood for hours under the hot sun - not because they feel sick, but out of fear. They want to know if they will be the next victims of a mysterious kidney disease that has killed thousands of farmers in Sri Lanka's rice basket.

Many have watched neighbors and loved ones - some only in their 30s - quickly succumb to cruel deaths after their kidneys gave out. In the worst-hit villages, it kills as many as 10 people every month. No one knows why.

"In some cases, you only know if a certain person died of kidney disease after the autopsy," said Kalyani Samarasinghe, 47, standing outside the health center with a handful of medical papers and a cotton ball taped to her arm.

"If you get a pain in the stomach or something, then you think: Is it the kidney?"

The disease has killed up to 20,000 people over the past 20 years and affected another 70,000 to 400,000. It has expanded from two districts to seven in the North Central province's dry zone, where farming was transformed after the introduction of modern techniques in the 1960s and 1970s. No cases have been detected elsewhere in the country, and research has failed to determine the cause.

Some blame the water, heavy use of pesticides and fertilizer. Others wonder if it is something in the food, or whether heavy metals or toxic algae could be the source. Villagers have been told to give up lake fish, aluminum cooking utensils and illicit home-brewed alcohol, but no one is sure if any of it helps.

Dr. Rajeeva Dassanayake, a kidney specialist at the area's largest hospital in Anuradhapura, has come to the screening to try to calm the crowd.

"You need not fear and flee from this place," he said. "There are a lot of things being said by many people. Until they have finished fighting each other and come up with an answer, we can say nothing."

Possible causes

Similar diseases are wiping out thousands of farmers in parts of Central America, India and Egypt. In hard-hit Nicaragua and El Salvador, some believe agrochemicals are the problem, while others think years of prolonged dehydration in the baking heat is shutting workers' organs down.

In Sri Lanka, a report published by the World Health Organization two years ago found kidney disease in 15 percent of adults across three affected districts. More women were affected overall, but men over 39 years old were more severely affected. Elevated cadmium and pesticide residues were detected in urine, leading the authors to surmise they may be damaging patients' kidneys over time, in combination with other factors such as arsenic.

Water, the source widely suspected as the culprit, came up clean. But the WHO study's Geneva-based author, Shanthi Mendis, said it could still be playing a key role when combined with other elements. She added that the government's top two priorities should be supplying safe drinking water to residents and regulating the use of agrochemicals.

The WHO report documented raised levels of cadmium and lead in certain plants and vegetables, such as lotus root and tobacco.