BOVINE SPONGIFORM ENCEPHALOPATHY SURVEILLANCE IN ARGENTINA

Bovine spongiform encephalopathy (BSE) is a new disease of cattle firs t described in the United Kingdom in November 1986. BSE belongs to the scrapie-related group of diseases. The epidemiological studies perfor med in the United Kingdom demonstrate that the BSE epidemic was caused by feeding cattle with ruminant-derived protein contaminated by a scr apie-like agent. Until June 1994, the disease had been detected in ind igenous cattle in Ireland, Switzerland and France. Three cases reporte d in Germany, two in the Sultanate of Oman, and single cases in the Fa lkland Islands (Islas Malvinas), Denmark, Portugal and Canada occurred in animals imported from the United Kingdom. Several countries have i mplemented surveillance programmes analysing the risk factors involved in the epidemic. An analysis of risk factors conducted in Argentina s hows that it is highly unlikely that BSE or scrapie exist in the count ry, or will arise via feed in the future. As a continuation of the ana lysis of risk factors, a surveillance programme was implemented in the field and in abattoirs. Specialised personnel were trained in the cli nical, histopathological and biochemical detection of the disease thro ugh a network of laboratories which covered 85% of the total cattle po pulation and 100% of the high-risk group (diary cows over five years o f age). By using a statistical procedure with reference to the bovine population in nine provinces, 1,019 brains from animals belonging to t he high-risk group were selected and studied by histopathological and biochemical analyses for BSE detection. The results were negative in a ll cases. It can be concluded from this analysis (with a sensitivity o f detection of 2.95 per 1,000, and 95% statistical confidence) that Ar gentina may be regarded as BSE-free, and that the importation of infec ted animals or by-products may represent the sole potential source of introduction of BSE infection into the country in the future.