For the last two decades, more than 20,000 people in Central America have died prematurely from an unknown kidney disease that is baffling scientists.

The disease -- called "chronic kidney disease of unknown origin," or CKDu -- primarily affects young men on the Pacific coast who are agricultural workers, especially those who cut sugarcane, CNN reported.

Costa Rica, El Salvador and Nicaragua have a higher concentration of those with the disease, also known as "creatinina," which is Spanish for creatinine, a biomarker of kidney strength.

In the U.S., diabetes and hypertension are related to kidney disease but are not related to CKDu. Scientists believe there are many factors that could be causing the disease but the most likely one is the sugarcane industry.

According to CNN, the industry has actually been a leading funding provider to researchers studying the illness.

Juan Salgado, who started cutting sugarcane near the Pacific coast of Nicaragua when he was 16 in 1966, started developing the symptoms of the disease when he was 51 years old. The symptoms included headaches, poor appetite, and feelings of faintness as well as his kidneys being severely damaged.

"I know, many, many workers who were colleagues of mine, who have already died, and I know also many who are not capable of working anymore because of the disease," Salgado said.

In 2008, documentary filmmaker Jason Glaser and Salgado co-founded La Isla Foundation, which is dedicated to helping sugarcane workers who have developed the disease as well as promote prevention. The foundation has also collaborated with researchers to study the illness.

In July, La Isla will meet with representatives from the Centers for Disease Control and Prevention and other researchers from various institutions to discuss the possibilities of expanding research, CNN reported.

Dr. Reina Turcios-Ruiz, a CCD resident adviser at the Central America Regional office in Guatemala, admitted that it will be a while before researchers get to the bottom of the disease.

"This is a complex problem," Turcios-Ruiz said. "It's going to take some time to find an answer, but I think it's important that we stick to it."