The potential for transmissible spongiform encephalopathies in non-ruminant livestock and fish

Pigs and poultry in the United Kingdom have undeniably been exposed to the bovine spongiform encephalopathy (BSE) agent. They consumed the same ruminant protein that gave rise to the BSE epidemic in cattle, but there has been no evidence of an epidemic in these species. Experimental investigations have shown pigs to be susceptible to infection by multiple parenteral challenge, but resistant to oral exposure with BSE-infected cattle brain. Current but incomplete evidence suggests that they are also resistant to oral challenge with sheep scrapie. Studies in domestic chickens indicate that they are resistant to both parenteral and oral challenge. Unfortunately, no published data exists on the susceptibility of fish to infection. Incidental findings in the brains of unexposed pigs are described that could otherwise give rise to concerns aboutthe presence of a transmissible spongiform encephalopathy in pig populations around the world.