Mad cow disease in Japan

Japan slow to act on BSE warnings

2 October 2001 12:00 GMT

by Sandra Katzman, BioMedNet News

published online at http://news.bmn.com

Signs of a potential epidemic of bovine spongiform encephalopathy (BSE) in Japan emerged last year, reveals an eminent Japanese virologist. That is around nine months before the government confirmed Asia's first case of BSE on a dairy farm near Tokyo.

"I have recognized possible incidence since the end of last year," noted Kazuya Yamanouchi, emeritus professor of virology at the University of Tokyo. He says his awareness of problems in Japan coincided with an increasing number of reports that the disease had moved from the UK onto continental Europe

"As we had imported tainted meat and bone meal [MBM] from the UK until 1996,it was likely that some cattle might have been exposed to BSE from MBM," he told BioMedNet News. "At first, the agriculture ministry was reluctant to totally ban MBM to all farm animals," added Yamounchi. But pressure from the public, which has blamed the ministry for putting industry's interests before concerns for human health, has seen an escalation in the government's response. "Everything is changing rapidly," he said.

At the weekend, the government banned the use of all MBM feed for cattle, thereby broadening an earlier restriction on imported MBM to domestic varieties as well. It also extended the feeding ban to pigs, chicken, and fish in case these animals finish up as ruminant feed, according to Yamanouchi. Furthermore, officials at the health, labor and welfare ministry today decided to call for a halt on the production and distribution of any food for human consumption that could contain parts of cattle organs most likely to be contaminated with the infectious agent implicated in BSE. "The ministry is poised to give the directive to the nation's 47 prefectural governments as well as food manufacturing industry organizations within a couple of days," reports the Mainichi Shimbun.

MBM, which is blamed for spreading BSE in the UK during the 1980s and early 1990s, contains brain, spinal cord, and intestinal parts from cattle and sheep. These organs, often referred to as specified bovine offal (SBOs), are reservoirs of the infectious prion protein, PrPSc, that is implicated in BSE and its human form, variant Creutzfeldt-Jakob Disease (vCJD). Sheep infected with scrapie, another spongiform encephalopathy, are not yet considered a risk to human health.

In 1996, when the British government confirmed the likely link between BSE and vCJD, Japanese officials urged farmers "not to feed MBM to ruminants, but the advice was not complied with well," recalled Yamanouchi.

In June, Japan ignored food safety advice from the European Union, which warned about a possible outbreak of BSE. "We should have accepted the EU assessment," said Tsutomu Takebe, minister of agriculture, forestry and fisheries, after the BSE case was confirmed.

Japan successfully eradicated foot-and-mouth disease last year by destroying 740 head of cattle, but it does not see itself ready to cope with a BSE epidemic and the likelihood of vCJD cases to follow, says Yamanouchi. "It is not well prepared as yet," he noted. Nevertheless, "research on diagnosis of prion diseases is at a high level," Yamanouchi added. "By law, we cannot import BSE materials, therefore we cannot use BSE materials for the tests. Prion research has been conducted on scrapie and CJD."

Most research in Japan has focused on sporadic CJD and, more recently, on cases in which an infectious agent in cadaveric dura mater, imported into Japan from Germany and transplanted into patients with neurosurgical disorders, is alleged to have caused CJD deaths.

Since 1998, the Japanese government has faced claims for compensation alleging that it failed to act swiftly to ban imports of the tainted brain tissue for therapeutic transplants. "Two hundred thousand people in Japan have had such implantation and are in the high risk category," said Katsumi Doh-ura, associate professor of neuropathology at Kyushu University. He plans to start clinical trials of a new medicine early next year: "We are aiming at such people," he told BioMedNet News.

A national CJD surveillance committee is examining all cases of CJD. "So far, we have not found any vCJD," said Yamanouchi, who is a member of the committee.

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