Japan is to introduce a new regulation for animal imports, in an effort to prevent outbreaks of diseases that could infect humans. But biologists worry that the rule will simply make it harder to do research.

From September 2005, the health ministry will require importers of birds and most mammals to provide a health certificate issued by the government of the exporting country. For rodents — including rats and mice — these certificates must show that the animals are clear of seven diseases that are infectious to humans, including plague, rabies and monkeypox. Imports of wild rodents will be banned outright.

The rule, which is part of a wider clamp-down on infectious diseases in Japan, will also require certificates for frozen carcasses, but not for frozen embryos.

On form: lab animals will have to be certified as healthy before they can be imported into Japan. Credit: N. PISARENKO/AP

The ministry says the main purpose of the rule is to keep wild rodents out of Japan. But it has decided not to exempt laboratory mice and rats that are bred abroad in strictly controlled conditions, for fear that some importers might abuse such exemptions.

The move comes at a time when demand for rats and mice is growing sharply. At a 16 December meeting to explain the new requirement, 140 researchers complained that it would make the import of lab animals time-consuming and expensive. “This will affect our research,” said Toshihiko Shiroishi, who studies mouse development at the National Institute of Genetics in Shizuoka.

Many institutions and universities in the United States and Europe already issue hygiene certificates indicating that rats or mice are free from specific pathogens. “We wonder why existing certificates won't work — and how much government certificates can help to prevent disease,” Shiroishi says.

He adds that the government's approach is unreasonable, considering that imports of lab rats or mice are not known to infect humans. Researchers say it will be difficult to get exporting countries to test animals for diseases such as rabies. Other countries have different rules on lab imports — the United States, for example, imposes few conditions, according to Japan's health ministry.

The ministry plans to ask exporting countries to be cooperative in issuing certificates. But Tadao Serikawa, director of the Institute of Laboratory Animals at Kyoto University, says it's not clear that this will help. The result could be “a big loss for scientific research” in Japan, he predicts.