There is an epidemic of primarily tubular-interstitial chronic kidney disease (CKD) clustering in agricultural communities in low-and-middle income countries (LMICs). Although it is currently unclear whether there is a common underlying cause, these conditions have been collectively termed CKD of unknown cause (CKDu). CKDu is estimated to have led to the premature deaths of tens to hundreds of thousands of young adults in LMICs over the last two decades. Thus, there is an urgent need to understand the aetiology and pathophysiology of these conditions and to develop preventive interventions. We have now established that CKDu exists in Central America (Nicaragua) and South Asia (India, Sri Lanka), but not in some other tropical countries. It is not clear yet whether the epidemics in Central America and South Asia have common causes or different causes, which is why it is important to conduct research using the same protocols and methods in these different regions. We have therefore established prospective studies in affected communities in Nicaragua, South India, and Sri Lanka to investigate the causes of the epidemics of CKDu, and factors which affect prognosis. The underlying hypothesis is that CKDu is caused by unknown factors to which the populations have become exposed, due to changes in agricultural practice or other environmental changes (e.g. water supply), over recent decades. The objectives of the collaboration are to investigate the environmental causes of renal decline in these high-risk populations, using standardised instruments capturing occupational and environmental exposures. We will address four proposed causes of CKDu: (i) metals and metaloids; (ii) agrochemicals; (iii) infections by organisms that affect the kidney; and (iv) heat/dehydration.

The authors have declared no competing interest.

This work was funded by grants from the UK Colt Foundation (CF/02/18) and the UK Medical Research Council (MR/V033743/1). The Dutch National Postcode Lottery also provided funding to Solidaridad to support a proportion of the initial fieldwork costs in Nicaragua. The work in Sri Lanka was funded by the National Science Foundation of Sri Lanka (RPHS/2016/CKDu 07), Ministry of Health, Nutrition and Indigenous Medicine and Worlds Health Organization Country Office Sri Lanka. The work in India was funded by grants from the Indian Council of Medical Research Extramural awarded to Dr. Ravi Raju Tatapudi under GITAM Institute of Medical Science and Research and the UK Medical Research Council (MR/V033743/1) awarded to the Indian Principal Investigator, Dr. Prabhdeep Kaur.

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