Juan José Amador

Changes in kidney function among Nicaraguan sugarcane workers

Abstract Background: There is an epidemic of chronic kidney disease (CKD) of unknown etiology in Central American workers. Objectives: To investigate changes and job-specific differences in kidney function over a 6-month sugarcane harvest season, explore the potential role of hydration, and measure proteinuria. Methods: We recruited 284 Nicaraguan sugarcane workers performing seven distinct tasks. We measured urine albumin and serum creatinine and estimated glomerular filtration rate (eGFR). Results: eGFR varied by job and decreased during the harvest in seed cutters (−8·6 ml/min/1·73 m2), irrigators (−7·4 ml/min/1·73 m2), and cane cutters (−5·0 ml/min/1·73 m2), as compared to factory workers. The number of years employed at the company was negatively associated with eGFR. Fewer than 5% of workers had albumin-to-creatinine ratio (ACR) >30 mg/g. Conclusions: The decline in kidney function during the harvest and the differences by job category and employment duration provide evidence that one or more risk factors of CKD are occupational.

Chronic kidney disease in Nicaragua: a qualitative analysis of semi-structured interviews with physicians and pharmacists

BackgroundNorthwestern Nicaragua has a high prevalence of chronic kidney disease (CKD) of unknown cause among young adult men. In addition, frequent occurrence of urinary tract infections (UTI) among men and a dysuria syndrome described by sugarcane workers as “chistata” are both reported. This study examines health professionals´ perceptions regarding etiology of these conditions and their treatment approaches, including use of potentially nephrotoxic medications.MethodsNineteen in-person semi-structured interviews were conducted in November 2010 among ten physicians and nine pharmacists practicing in the region.ResultsHealth professionals perceived CKD as a serious and increasing problem in the region, primarily affecting young men working as manual laborers. All interviewees regarded occupational and environmental exposure to sun and heat, and dehydration as critical factors associated with the occurrence of CKD. These factors were also considered to play a role in the occurrence of chistata in the region. Health professionals indicated that reluctance among workers to hydrate might be influenced by perceptions of water contamination. Symptoms often were treated with non-steroidal anti-inflammatory drugs (NSAIDs), diuretics and antibiotics. Physicians acknowledged that the diagnosis of UTI usually was not based on microbial culture and opined that the use of potentially nephrotoxic medications may be contributing to CKD.ConclusionsInterviews provided evidence suggesting that medications such as diuretics, antibiotics and NSAIDs are widely used and sold over the counter for symptoms that may be related to dehydration and volume depletion. These factors, alone or in combination, may be possible contributors to kidney damage. Acute kidney damage coupled with volume depletion and exposures including medications and infectious agents should be further evaluated as causal factors for CKD in this region.

Urine biomarkers of kidney injury among adolescents in Nicaragua, a region affected by an epidemic of chronic kidney disease of unknown aetiology

BACKGROUND An epidemic of chronic kidney disease (CKD) of non-traditional aetiology has been recently recognized by health authorities as a public health priority in Central America. Previous studies have identified strenuous manual work, agricultural activities and residence at low altitude as potential risk factors; however, the aetiology remains unknown. Because individuals are frequently diagnosed with CKD in early adulthood, we measured biomarkers of kidney injury among adolescents in different regions of Nicaragua to assess whether kidney damage might be initiated during childhood. METHODS Participants include 200 adolescents aged 12-18 years with no prior work history from four different schools in Nicaragua. The location of the school served as a proxy for environmental exposures and geographic locations were selected to represent a range of factors that have been associated with CKD in adults (e.g. altitude, primary industry and CKD mortality rates). Questionnaires, urine dipsticks and kidney injury biomarkers [interleukin-18, N-acetyl-d-glucosaminidase (NAG), neutrophil gelatinase-associated lipocalin (NGAL) and albumin-creatinine ratio] were assessed. Biomarker concentrations were compared by school using linear regression models. RESULTS Protein (3.5%) and glucose (1%) in urine measured by dipstick were rare and did not differ by school. Urine biomarkers of tubular kidney damage, particularly NGAL and NAG, showed higher concentrations in those schools and regions within Nicaragua that were defined a priori as having increased CKD risk. Painful urination was a frequent self-reported symptom. CONCLUSIONS Although interpretation of these urine biomarkers is limited because of the lack of population reference values, results suggest the possibility of early kidney damage prior to occupational exposures in these adolescents.

An epidemic of chronic kidney disease in Central America: an overview

For almost 2 decades, large areas of Central America have been impacted by an under-recognised epidemic of chronic kidney disease (CKD) of unknown causes whose victims are disproportionately young men of working age.1–5 Although exact figures are unavailable, based on estimates from our group, the death toll has likely reached at least 20 000. El Salvador, for example, has the highest overall mortality from kidney disease in the world (with Nicaragua and Honduras also included in the 10 highest countries), and CKD is the second leading cause of mortality among men of working age in the country.4 ,6 Furthermore, similar excesses of CKD of unknown cause have been reported in Sri Lanka,7 India8 and Egypt,9 where many of the epidemiological characteristics appear to be similar to the epidemic in Central America. Despite its scientific and public health importance and its potential global reach, we have found that most health researchers and public health practitioners are unaware of this epidemic. Our goal in this editorial is to provide a brief overview of the epidemiological, aetiological and public health dimensions of the epidemic. We are part of a multidisciplinary and multinational team of researchers whose involvement began in 2009 when we were selected to conduct research to search for the cause(s) of excess CKD by the participants of a mediation process managed by the Compliance Advisor/Ombudsman Office, an independent recourse mechanism for the World Bank10 aimed at responding to complaints from project-affected communities with the goal of providing a mechanism for representatives of the communities to sit at the table with recipients of World Bank private sector loans and address issues raised in the complaints. The participants included a sugar cane company in Nicaragua and a group of more than 2000 sick ex-workers and their families. During …

Leptospira seropositivity as a risk factor for Mesoamerican Nephropathy

Abstract Background: Leptospirosis is postulated as a possible cause of Mesoamerican Nephropathy (MeN) in Central American workers. Objectives: Investigate job-specific Leptospira seroprevalence and its association with kidney disease biomarkers. Methods: In 282 sugarcane workers, 47 sugarcane applicants and 160 workers in other industries, we measured anti-leptospiral antibodies, serum creatinine, and urinary injury biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), and N-acetyl-D-glucosaminidase (NAG). Results: Leptospira seroprevalence differed among job categories and was highest among sugarcane cutters (59%). Seropositive sugarcane workers had higher NGAL concentrations (relative mean: 1.28; 95% CI: 0.94–1.75) compared to those who were seronegative, with similar findings among field and non-field workers. Conclusions: Leptospira seroprevalence varied by job category. There was some indication that seropositivity was associated with elevated biomarker levels, but results were inconsistent. Additional studies may help establish whether Leptospira infection plays any role in MeN among Central American workers.