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Macroscopic nephropathy was observed in 506 pigs at slaughter in Bulgaria in 1993/94. Histopathological changes were mainly degenerative and proliferative, and were linked with kidney hypertrophy similar to that of the classical Danish Syndrome. Retention cysts formed by dilated tubules, activation or proliferation of capillary and vascular endothelium, and the development of neoplastic tissue were also observed. The most advanced pathology took the form of extensive interstitial fibrosis. Traces of ochratoxin A were found in the kidneys of the majority of 96 cases examined, and in some feed samples taken retrospectively from farms or commercial sources. The dietary ochratoxin concentration (100 micrograms/kg), calculated from serum analyses, closely matched the average of individually analysed feeds. In other feeds no ochratoxin A was detected and the cosmopolitan mycobiota isolated did not include the ochratoxinogenic Penicillium verrucosum that caused the Danish syndrome. Aspergillus ochraceus was rare and the isolates did not synthesise ochratoxin in laboratory culture. The unconfirmed diagnosis of ochratoxicosis suggests a complex or multi-toxin aetiology for this rather common chronic disease in Bulgaria.

The possible hazard of mycotoxin occurrence in foods and feeds and some food-borne mycotoxicoses is reviewed. Management of the risk of mycotoxin contamination using some useful preventive measures against mycotoxin contamination of foods/feeds during pre- and post-harvesting periods is considered. The physical and chemical methods of mycotoxin decontamination of foods/feeds are briefly described. The use of various feed additives as a method for prevention of the adverse effects of mycotoxins is reviewed. The processing of various foods and feeds is considered in a view to possible mycotoxin decontamination. The necessary hygiene control and risk assessment in regard to mycotoxin contamination of foods and feeds in addition to some useful prophylactic measures are briefly described. A short reference is made concerning the most successful methods of veterinary hygiene control in order to prevent a possible entering of some mycotoxins in commercial channels with a view to human health.

Spontaneous nephropathy in Bulgaria, which is observed frequently during meat inspection and which differs morphologically from the classical description of mycotoxic porcine/chicken nephropathy as made in Denmark, was found to have a multi-mycotoxic aetiology being mainly provoked by a combined effect of ochratoxin A, penicillic acid and fumonisin B1 in addition to a not-yet-known metabolite. Mean contamination levels of ochratoxin A were consecutively low (188.8 and 376.4 microg kg(-1)) in contrast to high contamination levels of fumonisin B1 (5564.1 and 3254.5 microg kg(-1)) and penicillic acid (838.6 and 904.9 microg kg(-1)) for 2006 and 2007, respectively. Some other mycotoxins with lower importance such as citrinin, penitrem A, etc., may also influence clinicopathological picture of this nephropathy. A heavy contamination with Gibberella fujikuroi var. moniliformis (Fusarium verticillioides) and Penicillium aurantiogriseum complex (mainly Penicillium polonicum) was observed in almost all examined feed samples coming from pig and chick farms with nephropathy problems from Bulgaria. In contrast, low contamination with Aspergillus ochraceus, Penicillium verrucosum and Penicillium citrinum was observed in the same feed samples and these species were isolated as very rare components of the mycobiota.