[Brain emboli in the lungs of cattle].
There is no information whether the BSE agent is introduced into the human food chain through contamination of the lungs of cattle with central nervous system tissue (CNS). Studies in the United Kingdom and in the USA showed that CNS tissue could contaminate the lungs after using pneumatic powered air injection stunners (e.g. "The Knocker") or after pithing. Thus, pithing was forbidden in the European Union since January 2001. In German abattoirs conventional cartridge-fired stunners (e.g. model by Schermer) are usually applied. Pithing was used up to December 2000 in approx. 75% of the German abattoirs. In the present study 323 lungs of cattle were analysed for CNS. The lungs were derived from cattle exclusive stunned by use of the knocker from Schermer. 60% of the lungs contained emboli which were tested with immuno chemistry as well as immuno histochemistry to detect CNS. Two of 108 pooled samples showed a faint immuno reaction in the anti-NSE and anti-GFAP immunoblot. Further two particles showed a faint reaction for NSE and GFAP in immuno histochemistry, thus suggesting the presence of CNS. Even though CNS tissue could not be shown in the histological investigation, we used our findings to estimate the worst case scenario for human BSE exposure risk (HER) by lung contaminated by CNS emboli. The content of CNS in the samples was estimated to be about 0.11% when the respective immuno reactions were calibrated against standards containing known brain concentrations. Under the assumption that only one lung in the pooled samples was contaminated with BSE-infected central nervous tissue, the HER was calculated to reach a maximum of 2.2 x 10(-5) CoID50/consumer after consumption of a sausage with a portion of 10% lung. The results of our study suggest that the contamination of the lung with CNS after using a conventional cartridge-fired stunner cannot be excluded, however, the incidence appears to be very low. In addition, presumed CNS emboli, if at all, are microscopically small. Furthermore the incidence of BSE in Germany is very low and lungs of cattle are usually not consumed. Thus we can judge the potential for human oral exposure after consumption of lungs of cattle which were stunned in Germany to be extremely low. A final assessment, however, is impossible as there is no knowledge about the minimum infectious dose for humans.
Horlacher
Sabine
S
Institut für Tierärztliche Nahrungsmittelkunde, Justus-Liebig-Universität Giessen.
Lücker
E
E
Eigenbrodt
E
E
Wenisch
Sabine
S
D000003:Abattoirs; D000818:Animals; D002417:Cattle; D016643:Encephalopathy, Bovine Spongiform / Q000453:epidemiology / Q000635:transmission*; D005506:Food Contamination; D005858:Germany / Q000453:epidemiology; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry / Q000662:veterinary; D020766:Intracranial Embolism / Q000473:pathology / Q000662:veterinary*; D008168:Lung / Q000737:chemistry / Q000473:pathology*; D010751:Phosphopyruvate Hydratase / Q000032:analysis
D005904:Glial Fibrillary Acidic Protein; D010751:Phosphopyruvate Hydratase