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A Puzzling Kidney Disease Epidemic Is Sweeping Through The Tropics

828 A Puzzling Kidney Disease Epidemic Is Sweeping Through The Tropics
There has been an increase of CKDu in sugar cane workers in Central America. satit_srihin/Shutterstock

Scores of men living in the southern Indian state of Andhra Pradesh are being diagnosed with a chronic kidney disease, and yet researchers have no idea what is causing this sudden epidemic of cases. Normally, patients who are diagnosed with the disease either have diabetes or hypertension before the problem develops further, and yet these new patients have no previous reported health issues. Known as chronic kidney disease of unknown etiology (CKDu), scientists are scrambling to figure out exactly what is going on.

CKDu is deadly because it is difficult to detect. With few early symptoms, by the time patients are diagnosed, especially in remote regions of developing nations, the kidneys have been damaged beyond repair. This leads to high blood pressure and an increase in a protein called creatinine in the blood – the hallmark of early-stage kidney disease. Once diagnosed, the prognosis is not good, as the irreversible disease eventually means that patients will be unable to work and have to be placed on dialysis, something that is extremely debilitating for men from poor backgrounds who have families to support.   


The strange thing about the disease is that this isn’t the first time these symptoms have surfaced. In fact, for the past few years, thousands of men aged between 30 and 55 have been diagnosed with CKDu in Central America, mainly in Mexico, Guatemala, Nicaragua, and the Pacific Coast of El Salvador. It has been estimated that an astonishing 20,000 men in Central America have died prematurely due to this unknown epidemic, a five-fold increase in 20 years. What exactly has been causing it, however, has flummoxed researchers.

Interestingly, in Mesoamerica it seems to be predominantly affecting those who work on sugar cane plantations, while other agricultural workers – such as those in rice-growing regions of Sri Lanka – also seem to be affected. This is a pattern repeated in the young men being diagnosed in India, who are also doing hard manual labor out in the Sun. This has led to one theory that it might be related to chronic dehydration.

In a study on sugar cane workers in Costa Rica, researchers found high levels of uric acid crystals in their urine, which built up as the day progressed. They think that these crystals could then be damaging the kidneys, leading to the development of CKDu, which would explain the high prevalence among men working out in the fields all day.

But others disagree. Two groups of researchers have been looking at the levels of silica found in the water in Andhra Pradesh, with one group investigating whether or not it is naturally occurring and another looking at whether or not it is the result of excessive pesticide use. The latter is one of the leading theories to the recent increase in prevalence of CKDu in the farming communities of Sri Lanka, where so many cases have now been diagnosed that it has become a public health crisis. In Sri Lanka, it is argued that the chemicals sprayed on the fields are the cause of kidney disease in the field workers.


What is clear, however, is that the researchers studying these epidemics in different corners of the world need to start collaborating. If they can find a link between cases reported in Sri Lanka, India, and Central America, it could give them a vital lead to follow. But equally, there is also the possibility that what we are looking at are separate illnesses that have similar outcomes. 


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