Tokyo

East Asian countries are bracing themselves for a possible wave of mad cow disease, after the first case of bovine spongiform encephalopathy (BSE) was confirmed in an animal born in Japan (see Nature 413, 240; 2001).

The source of the infection is thought to be cattle feed containing animal parts, which British farmers dumped in the region when demand slumped in Europe in the early 1990s (see graph). Thailand and Indonesia were among the heaviest importers.

UK exports of flours, meat pellets and meat offal, unfit for human consumption, during 1979–95.

“If BSE got into cattle feed in Asia at that time, it's about time for the disease to show up,” says Sumolya Kanchanapangka, associate professor of veterinary anatomy at Bangkok's Chulalongkorn University and adviser to Thailand's food-safety agency.

If the region has underestimated the risk of BSE, experts point out, its people could be at risk of developing new variant Creutzfeldt–Jakob disease (vCJD), the neurodegenerative disease thought to be caused by eating brain, spinal cord and other organs from BSE-infected cattle. Workers in Thai slaughterhouses don't seem very thorough about removing these, says Kanchanapangka. In Korea, where “cow brain is a delicacy and every part of the cow is eaten, reports of BSE would lead to panic”, says an agriculture ministry representative there.

Grave disclosure: Japan's agriculture minister, Tsutomu Takebe, breaks the news. Credit: KOJI SASAHARA/AP

Japanese government and industry officials previously argued that Japan was at little risk of BSE because the imported British meat and bone-meal was fed only to pigs and chicken, not to cattle. Japanese cattle are normally raised on beer and soy-based feed. But the confirmed case shows that this was not always so.

Earlier this year, when reports circulated that a European Commission study group was poised to report that Japan was at high risk of the disease, Japan stopped cooperating with the study, effectively blocking it, according to a European official.

Other Asian animal-health officials still say that the animal feed was not given to cattle. Thai and Korean officials say that only pig and chicken farmers could afford the imported feed. But the European official, who declined to be identified, said that experience in Europe suggests that such restrictions don't always work.

Korean and Thai officials point out that, unlike Japan, their countries have no documented cases of scrapie, a disease of goats and sheep that is thought to be related to BSE. And the procedure of reprocessing animal parts for feed is rare in the region, they say.

Korea, Singapore and other neighbouring countries have responded to the Japanese case with immediate bans on the import of Japanese beef. Japan, meanwhile, says it will run BSE tests on one million cows, at a cost of some ¥3 billion (US$25 million).