A killer in the fields

So many men in Chichigalpa, Nicaragua, have died from kidney failure, the town is known as the Island of the Widows. The condition that afflicts them — called chronic kidney disease of unknown origin, or CKDu — is, as its name implies, a mystery. It is a tubulointerstitial kidney disease that affects people everywhere. But researchers don’t know why rates are much higher in low-lying, hot agricultural areas like Chichigalpa, which is surrounded by sugarcane fields.

Shuchi Anand, MD, a Stanford Medicine associate professor of nephrology, has been interested in the disease since it was first described in the 1990s.

“Two-thirds of the people with this disease are men, many in their 30s and 40s,” said Anand, who is the director of the Center for Tubulointerstitial Kidney Disease. “This is the prime age of work and income generation. They are the breadwinners. This disease can devastate families.”

Nephrologists have identified hot spots for the condition in Central America and South Asia, where up to 30% of households include someone with it. Anand has found that California’s agricultural regions also show higher-than-typical rates of kidney disease, though she hasn’t been able to confirm them as hot spots for CKDu. Because most farmworkers are migrants and are often transient, they’re difficult to study.

The disease is stealthy. Most of its victims experience no symptoms until they reach end-stage renal disease, when their bodies swell, they lose their appetites and they experience brain fog. Without dialysis or transplantation, treatments not readily available in communities where the disease is common, it is fatal.

While most patients work in agriculture, Anand said researchers are finding high rates of the disease among brickmakers and construction workers who also labor under a hot sun. “Our primary premise is that heat is amplifying the disease,” she said.

Contaminated water is a suspect. Shuchi’s research suggests that communities with poorer water quality are seeing more cases. One hot spot is in a mining area, indicating that metal exposure could also be a factor.

“These deaths of young workers didn’t occur in the 1960s and 1970s,” Anand said. “And that gives some hints as to the cause. We’re looking at changes in the environment, whether that’s temperature, agricultural practices, water quality or a combination of factors.”

To help pinpoint a cause, Anand and a team of epidemiologists, biostatisticians and body temperature experts plan to study devices such as cooling gloves or headbands to see if they result in fewer cases of the condition.

She is also studying the outliers — women. Because men are more likely to contract the disease, finding what sets apart the women who have it may offer clues. She also hopes to sniff out differences by comparing communities that are severely affected with those that are less affected.

There is some good news. In parts of South Asia where the disease cluster was first detected, Anand said, clinicians feel that rates of the disease are leveling off, perhaps because agricultural workers are being provided more shade and more work breaks or because drinking water is cleaner.

Since she began her quest to find the culprit behind the condition, Anand said, “We have better data now, but we still don’t have a smoking gun. We all hope to find it so we can eliminate the cause and eliminate the disease.”