Chronic kidney disease of nontraditional etiology in Central America: a provisional epidemiologic case definition for surveillance and epidemiologic studies / Enfermedad renal crónica de causas no tradicionales en Centroamérica: una definición de caso provisional para vigilancia y estudios epidemiológicos

Over the last two decades, experts have reported a rising number of deaths caused by chronic kidney disease (CKD) along the Pacific coast of Central America, from southern Mexico to Costa Rica. However, this specific disease is not associated with traditional causes of CKD, such as aging, diabetes, or hypertension. Rather, this disease is a chronic interstitial nephritis termed chronic kidney disease of nontraditional etiology (CKDnT). According to the Pan American Health Organization (PAHO) mortality database, there are elevated rates of deaths related to kidney disease in many of these countries, with the highest rates being reported in El Salvador and Nicaragua. This condition has been identified in certain agricultural communities, predominantly among male farmworkers. Since CKD surveillance systems in Central America are under development or nonexistent, experts and governmental bodies have recommended creating standardized case definitions for surveillance purposes to monitor and characterize this epidemiological situation. A group of experts from Central American ministries of health, the U.S. Centers for Disease Control and Prevention (CDC), and PAHO held a workshop in Guatemala to discuss CKDnT epidemiologic case definitions. In this paper, we propose that CKD in general be identified by the standard definition internationally accepted and that a suspect case of CKDnT be defined as a person age < 60 years with CKD, without type 1 diabetes mellitus, hypertensive diseases, and other well-known causes of CKD. A probable case of CKDnT is defined as a suspect case with the same findings confirmed three or more months later.

En los dos últimos decenios, los expertos han notificado un aumento del número de defunciones causadas por enfermedad renal crónica (ERC) a lo largo de la costa del Pacífico de Centroamérica, desde el sur de México hasta Costa Rica. Sin embargo, esta enfermedad específica no está asociada con las causas tradicionales de ERC, como envejecimiento, diabetes o hipertensión. En cambio, esta enfermedad es una nefritis intersticial crónica denominada enfermedad renal crónica de causas no tradicionales (ERCnT). Según la base de datos de mortalidad de la Organización Panamericana de la Salud (OPS), se registran tasas de mortalidad elevadas relacionadas con la enfermedad renal en muchos de estos países; las más elevadas se informaron en El Salvador y Nicaragua. Esta enfermedad ha sido identificada en algunas comunidades agrícolas, predominantemente en trabajadores agrícolas varones. Como los sistemas de vigilancia de la ERC en Centroamérica están en desarrollo o son inexistentes, los expertos y los organismos gubernamentales han recomendado elaborar definiciones de caso estandarizadas con fines de vigilancia, para monitorear y caracterizar esta situación epidemiológica. Un grupo de expertos de los ministerios de salud centroamericanos, los Centros para el Control y la Prevención de Enfermedades de los Estados Unidos (CDC) y la OPS se reunieron en un taller realizado en Guatemala para debatir posibles definiciones de caso epidemiológicas de ERCnT. En este artículo proponemos que, en general, la ERC se identifique mediante la definición normalizada internacionalmente aceptada y que un caso presunto de ERCnT se defina como: persona menor de 60 años con ERC, sin diabetes mellitus de tipo I, enfermedades hipertensivas ni otras causas conocidas de ERC; y un caso probable de ERCnT se defina como un caso presunto con los mismos resultados confirmados tres meses después o más.

Chronic kidney disease of nontraditional etiology in Central America: a provisional epidemiologic case definition for surveillance and epidemiologic studies.

SYNOPSIS Over the last two decades, experts have reported a rising number of deaths caused by chronic kidney disease (CKD) along the Pacific coast of Central America, from southern Mexico to Costa Rica. However, this specific disease is not associated with traditional causes of CKD, such as aging, diabetes, or hypertension. Rather, this disease is a chronic interstitial nephritis termed chronic kidney disease of nontraditional etiology (CKDnT). According to the Pan American Health Organization (PAHO) mortality database, there are elevated rates of deaths related to kidney disease in many of these countries, with the highest rates being reported in El Salvador and Nicaragua. This condition has been identified in certain agricultural communities, predominantly among male farmworkers. Since CKD surveillance systems in Central America are under development or nonexistent, experts and governmental bodies have recommended creating standardized case definitions for surveillance purposes to monitor and characterize this epidemiological situation. A group of experts from Central American ministries of health, the U.S. Centers for Disease Control and Prevention (CDC), and PAHO held a workshop in Guatemala to discuss CKDnT epidemiologic case definitions. In this paper, we propose that CKD in general be identified by the standard definition internationally accepted and that a suspect case of CKDnT be defined as a person age < 60 years with CKD, without type 1 diabetes mellitus, hypertensive diseases, and other well-known causes of CKD. A probable case of CKDnT is defined as a suspect case with the same findings confirmed three or more months later.

Blood lead levels and risk factors for lead poisoning among children in a Mexican smelting community.

The authors evaluated mean blood lead levels (BLLs) and the prevalence of elevated BLLs in children 1-6 yr of age living in Torreón, Mexico, and assessed risk factors for lead exposure in these children. The study involved a simple random sample of households in the area around a local smelter, as well as a 2-stage cluster sample of neighborhoods and households in the remainder of Torreón. The geometric mean BLL of children in this study (N = 367) was 6.0 microg/dl (95% confidence interval [CI] = 5.2, 6.8) (0.29 microM/l [95% CI = 0.25, 0.33]). Twenty percent of the children had BLLs > or = 10 microg/dl (0.48 microM/l), and 5% had BLLs > or = 20 microg/dl (0.97 microM/l). In multivariate analyses, distance from the smelter, amount of income, and education level of the primary caregiver predicted BLLs. In the environmental risk factor subsample (n = 124), dust and soil lead levels were associated with BLLs and distance from the smelter. BLLs in this study were moderately high, but the levels were lower than those in other smelting communities prior to remediation.

Determinants of blood-lead levels in children in Callao and Lima metropolitan area.

OBJECTIVES: To determine blood lead levels in urban populations of children (n = 2,510) and women (n = 874) in the early postpartum in certain districts of Lima and Callao, and to correlate those levels with particular exposures. MATERIAL AND METHODS: Between July 1998 and January 1999 cross sectional study was conducted. The study population was selected using three sampling strategies in the government operated school system and from public pediatric and maternity hospitals at Lima and Callao, Peru. Study personnel were trained to collect finger stick blood samples with a protocol that minimizes external lead contamination. Lead determinations in blood and environmental samples were performed at the study site using portable anodic striping voltamenters. To determine the simultaneous effects of different predictors on blood lead levels, multivariate regression models were used to estimate adjusted mean differences. RESULTS: The mean blood lead level in the children studied was 9.9 micrograms/dl ranging from 1 microgram/dl to 64 micrograms/dl with 29% of the children displaying values greater than 10 micrograms/dl and 9.4% at levels greater than 20 micrograms/dl. Among the women, the mean was 3.5 micrograms/dl (SD = 2.4 micrograms/dl), and 2.4% (n = 21) displayed levels greater than 10 micrograms/dl. Important differences were observed between the sample locations, and the highest levels were documented in the port region near Callao. The mean level of blood lead in this group was 25.6 micrograms/dl (SD = 4.6 micrograms/dl), while among the rest of the sample it was 7.1 micrograms/dl (SD = 5.1 micrograms/dl). The presence of a mineral storage area signified a difference in exposure in excess of 13 micrograms/dl for children living near the port area in contrast to the other children who were not as close to such fixed sources of lead exposure. For the participants in Lima, the risk of showing levels above 10 micrograms/dl was associated with exposure to high vehicular traffic. CONCLUSIONS: In metropolitan Lima, we conclude that the mean blood lead levels of the populations studied were not alarming and that a positive health impact can be made by a reduction of lead in gasoline. With regard to the port area, the study demonstrates that the presence of mineral storage areas pose a detrimental risk factor for the health of the children living in this area. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.

Use of isotope ratios to identify sources contributing to pediatric lead poisoning in Peru.

In 1998, a school-based blood lead level (BLL) survey of 2,510 children, conducted in Lima and Callao, Peru, revealed elevated BLLs in children from 2 Callao schools (mean BLL = 25.6 microg/dl; n = 314) and in children from Callao overall (mean BLL = 15.2 microg/dl; n = 898), compared with children from Lima (mean BLL = 7.1 microg/dl; n = 1,612). Public health officials at Peru's Direccion General de Salud Ambiental (DIGESA) hypothesized that a possible source of the elevated pediatric BLLs observed in Callao was a large depository near the port where mineral concentrates are stored prior to shipment. The U.S. Centers for Disease Control and Prevention worked with DIGESA to identify source(s) that contributed to the pediatric lead poisonings by comparing isotopic profiles of lead in blood, mineral, gasoline, and air filter samples. The lead isotope ratio (IR) observed in mineral samples from the depository in Callao differed from those in gasoline samples from Lima and Callao. The blood lead IRs of children living near the depository were similar to the IRs of the mineral samples and different from the IRs of the gasoline samples, suggesting that lead from the depository-and not gasoline-was the primary source of lead in these children. Lead IR analysis of regional air filter samples supported these findings.

Determinants of blood-lead levels in children in Callao and Lima metropolitan area

OBJETIVO: Determinar los niveles de plomo en sangre en una muestra compuesta por niños y mujeres en el posparto temprano, residentes en Lima y El Callao. Investigar los determinantes de estos niveles y algunas fuentes de exposición. MATERIAL Y MÉTODOS: Entre julio de 1998 y enero de 1999 se llevó a cabo una encuesta en el área metropolitana de Lima y en El Callao, Perú. La población de estudio fue identificada mediante tres estrategias de muestreo y con la cual se seleccionaron escuelas públicas y hospitales pediátricos y gineco-obstétricos. El personal que participó en el estudio recibió entrenamiento para la técnica de punción digital y puso especial énfasis en controlar la contaminación externa con plomo. Las determinaciones del metal en sangre y muestras ambientales se llevaron a cabo utilizando voltametría anódica. Para determinar los efectos simultáneos de diferentes predictores sobre los niveles de plomo en sangre se usaron modelos de regresión multivariada para estimar diferencias de media y ajustadas. RESULTADOS: Los niveles promedio de plomo en sangre fueron de 9.9 µg/dl de una variación entre 0 y 64 µg/dl. El 29 y 9.4% de los niños presentaron valores por encima de 10 µg/dl y 20 µg/dl,respectivamente. Para las mujeres el promedio de plomo en sangre fue de 3.5 µg/dl (DE=2.4) y 2.4% (n=2l) presentaron niveles superiores a 10 µg/dl. Se observaron diferencias importantes en relación con el sitio de residencia; los niveles más altos se documentaron en la zona de El Callao. Para este grupo la media de plomo en sangre fue de 25.6 µg/dl (DE=4.6) mientras que para el resto de la muestra el promedio de plomo en sangre fue de 7.1 µg/dl (DE=5.l). En esta zona se detectó un área de almacenamiento de minerales como una fuente importante de exposición. Los niños que viven cerca de esta área tenían en promedio un exceso de 13 µg/dl en sangre. Para los participantes de la zona de Lima el riesgo de presentar niveles por encima de 10 µg/dl se asoció con la exposición a tráfico vehicular. CONCLUSIONES: Para Lima Metropolitana se puede concluir que los niveles de plomo en sangre no representan un problema urgente, sin embargo, el reducir el plomo de la gasolina se acompaña de un beneficio importante. En contraste, para el área cercana al puerto de El Callao, nuestro estudio demuestra la presencia de sitios de almacenamiento de minerales que representan un riesgo importante para la salud de los niños que viven en esta zona.