Balkan endemic nephropathy: an update on its aetiology.

Balkan endemic nephropathy (BEN) is a unique, chronic renal disease frequently associated with upper urothelial cancer (UUC). It only affects residents of specific farming villages located along tributaries of the Danube River in Bosnia-Herzegovina, Croatia, Macedonia, Serbia, Bulgaria, and Romania where it is estimated that ~100,000 individuals are at risk of BEN, while ~25,000 have the disease. This review summarises current findings on the aetiology of BEN. Over the last 50 years, several hypotheses on the cause of BEN have been formulated, including mycotoxins, heavy metals, viruses, and trace-element insufficiencies. However, recent molecular epidemiological studies provide a strong case that chronic dietary exposure to aristolochic acid (AA) a principal component of Aristolochia clematitis which grows as a weed in the wheat fields of the endemic regions is the cause of BEN and associated UUC. One of the still enigmatic features of BEN that need to be resolved is why the prevalence of BEN is only 3-7 %. This suggests that individual genetic susceptibilities to AA exist in humans. In fact dietary ingestion of AA along with individual genetic susceptibility provides a scenario that plausibly can explain all the peculiarities of BEN such as geographical distribution and high risk of urothelial cancer. For the countries harbouring BEN implementing public health measures to avoid AA exposure is of the utmost importance because this seems to be the best way to eradicate this once mysterious disease to which the residents of BEN villages have been completely and utterly at mercy for so long.

Chronic dietary exposure to aristolochic acid and kidney function in native farmers from a Croatian endemic area and Bosnian immigrants.

BACKGROUND AND OBJECTIVES: Improvements in agricultural practices in Croatia have reduced exposure to consumption of aristolochic acid-contaminated flour and development of endemic (Balkan) nephropathy. Therefore, it was hypothesized that Bosnian immigrants who settled in an endemic area in Croatia 15-30 years ago would be at lower risk of developing endemic nephropathy because of reduced exposure to aristolochic acid. To test this hypothesis, past and present exposure to aristolochic acid, proximal tubule damage as a hallmark of endemic nephropathy, and prevalence of CKD in Bosnian immigrants were analyzed. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this cross-sectional observational study from 2005 to 2010, 2161 farmers were divided into groups: indigenous inhabitants from endemic nephropathy and nonendemic nephropathy villages and Bosnian immigrants; α-1 microglobulin-to-creatinine ratio >31.5 mg/g and eGFR<60 ml/min per 1.73 m(2) were considered to be abnormal. RESULTS: CKD and proximal tubule damage prevalence was significantly lower in Bosnian immigrants than inhabitants of endemic nephropathy villages (6.9% versus 16.6%; P<0.001; 1.3% versus 7.3%; P=0.003, respectively); 20 years ago, Bosnian immigrants observed fewer Aristolochia clematitis in cultivated fields (41.9% versus 67.8%) and fewer seeds among wheat seeds (6.1% versus 35.6%) and ate more purchased than homemade bread compared with Croatian farmers from endemic nephropathy villages (38.5% versus 14.8%, P<0.001). Both Croatian farmers and Bosnian immigrants observe significantly fewer Aristolochia plants growing in their fields compared with 15-30 years ago. Prior aristolochic acid exposure was associated with proximal tubule damage (odds ratio, 1.64; 95% confidence interval, 1.04 to 2.58; P=0.02), whereas present exposure was not (odds ratio, 1.31; 95% confidence interval, 0.75 to 2.30; P=0.33). Furthermore, immigrant status was an independent negative predictor of proximal tubule damage (odds ratio, 0.40; 95% confidence interval, 0.19 to 0.86; P=0.02). CONCLUSIONS: Bosnian immigrants and autochthonous Croats residing in endemic areas are exposed significantly less to ingestion of aristolochic acid than in the past. The prevalence of endemic nephropathy and its associated urothelial cancers is predicted to decrease over time.

Haematological features of the population of the area of Croatia, Yugoslavia, endemic for Balkan nephropathy.

Normochromic, normocytic anaemia is a sign recognized as essential for the diagnosis of Balkan endemic nephropathy, although its relationship to the disease is still unclear. The aim of this study was to investigate whether a random sample of the population of a village endemic for nephropathy differed from the population of a village with no clinical case of nephropathy with respect to certain basic haematological parameters. During a screening campaign in 1984, 133 blood samples were collected from the endemic village and 40 from the nonendemic village and analysed for a number of haematological parameters; in 1991, 449 samples were collected in the endemic village and 156 in the nonendemic village and analysed for haemoglobin content and red blood cell count. Whereas in 1984 the haemoglobin content and red blood cell count were significantly lower in the endemic village (p less than 0.01), in 1991 the erythrocyte count was much lower in the nonendemic village and there was no difference in haemoglobin concentration. Several controversial explanations, all of them speculative, are offered.

[Rescreening study of the population of the endemic village Gorno Peshtene, Vrachansk]. / Reskriningovo izsledvane na naselenieto ot endemichnoto selo Gorno Peshtene, Vrachansko.

The number of the recorded patients with Balkan endemic nephropathy gradually decreased during the period after 1970. The author explains that by the interrupted prophylactic examinations and screenings of the population from the endemic villages during that period. The results obtained with the repeated screening, after 16 years, of the population of one hyperendemic village in Vratza district support that view point. New 74 patients with Balkan endemic nephropathy were found, 8 of them with uroepithelial tumours of the upper urinary pathways. Together with the 45 patients known so far, their total number amounts to 119, suggesting that 13,7 per cent of the population from that village has been affected by the disease. Those data convincingly suggest that the morbidity rate from Balkan endemic nephropathy in our country has not decreased - only its recording has been neglected, due to the interruption of the active search of those patients via screening of the population from the endemic settlements. That emphasizes the great importance of those investigation methods in the establishment of the real Balkan endemic nephropathy morbidity.