Clinical Pearls & Morning Reports
In recent years, numerous cases of chronic kidney disease have emerged among agricultural workers, as well as among others performing manual labor, in various regions of the world. The disease does not appear to be due to the classic causes of kidney disease (e.g., diabetes, hypertension, and glomerular disease). An early report on an upsurge in chronic kidney disease in Central America came from El Salvador in 2002. Within a short time, multiple reports confirmed higher-than-expected rates of chronic kidney disease among sugarcane workers and other agricultural workers who were laboring in the fields along the Pacific Coast of Central America, from Guatemala to Panama, and the name Mesoamerican nephropathy was proposed for the disorder. Read the Review Article here.
Q: Where besides Central America does this condition occur?
A: A spate of chronic kidney disease of unknown origin has also been identified in the North Central Province of Sri Lanka among persons working in the rice paddies in rural regions. Numerous cases of chronic kidney disease have been reported among rural farmers in India, especially in Central India. There are reports of high rates of chronic kidney disease in other hot regions of the world (e.g., among rural farmers in Tierra Blanca, Veracruz State, Mexico, where the major crops are sugarcane, cantaloupe, papaya, and rice). Two reports suggest that the disease may also be present in southern Egypt and the Sudan.
Q: Is the etiology of chronic kidney disease in these agricultural communities known?
A: The disease is strongly associated with working and living in a hot environment, but whether the cause is a toxin, an infectious agent, a heat-associated injury, or a combination of factors is not yet known.
A: Affected sugarcane workers are usually discovered to have an elevated serum creatinine level when they undergo screening before working in a seasonal harvest. Those affected are usually men who have worked for two or more seasons, are between 20 and 50 years old, are asymptomatic, and have normal or only slightly elevated blood pressure and normal blood glucose levels. At the time of diagnosis, the kidney disease is commonly advanced, at stage 3 or 4 (eGFR, 15 to 60 ml per minute per 1.73 m2), with a subsequent decline in the eGFR of 3.8 to 4.4 ml per minute per 1.73 m2 per year. Kidney-biopsy specimens from workers with established Mesoamerican nephropathy show chronic interstitial disease, tubular atrophy, inflammation, and interstitial fibrosis. Glomeruli may be characterized by focal wrinkling of the glomerular basement membrane, a finding that is consistent with ischemia, and global glomerulosclerosis is common. Immune deposits and changes characteristic of diabetes have not been observed, and signs of hypertensive disease have been minimal or absent. Milder and less frequent manifestations of kidney disease have also been observed in women and children living in the region.
A: Because chronic kidney disease in agricultural communities is largely an occupational and environmental health problem, primary and secondary prevention strategies have focused on preventing heat-associated health risks, mitigating nephrotoxin exposures, and conducting medical surveillance in at-risk populations to identify illness at subclinical and clinical stages. In Central America, most preventive policies and actions have been focused on reducing heat and sun exposure and improving hydration with safe water and electrolytes. Kidney biopsy may be useful to confirm the disease. Treatment is supportive. Patients in whom nephropathy progresses to end-stage kidney disease will require dialysis or transplantation, although these treatments are not always available.