DISEASES caused by plague-infested fleas dropped on China by Japan during the Second World War remained virulent long after the war ended, expert witnesses told a Tokyo court last week.

Chinese doctors described for the first time how the effects of the biological weapon attacks continued for years after the Japanese Imperial Army spread infected fleas in the city of Ningbo, Zhejiang province, in October 1940. Similarly, cases of typhus persisted into the 1950s in the city of Quzhou, Zhejiang province, which was attacked the same month.

The Tokyo District Court is hearing a suit for compensation filed by 180 relatives of victims of Japan's biological warfare campaign, after 109 people died following a 34-day outbreak of bubonic plague in Ningbo.

However, the Japanese government still denies that its troops used biological weapons at the time, and the plaintiffs continue to wait for an apology.

The town authorities tried to eradicate the plague by burning hospitals and infected houses. But according to local bacteriologist Huang Ketai, new cases of plague cropped up in Ningbo until 1948. Qiu Ming-xuan, a survivor of a bacterial attack, and a doctor at the Quzhou epidemic-prevention station, said Japanese planes dropped paper bags on his city, each containing about ten fleas, as well as rags and grains of wheat. Qiu believes the items carried bubonic plague, cholera, typhoid and anthrax bacteria. Qiu has also studied the after-effects of attacks on Quzhou, and says cases of typhus were found there as late as 1953.

"Even 60 years on we are still finding positive antibodies to bubonic plague in rats, dogs, cats and other animals," Qiu told reporters. "And not only animals. Every year a certain number of healthy people develop typhoid problems, so this problem still exists."

Qiu testified that residents fled Quzhou after the attack, unwittingly helping to spread the diseases to surrounding rural areas. He added that Quzhou had never experienced bubonic plague in its history, yet around 50,000 people died from the disease in the years following the attack.

Bacteriologist Huang gave the first evidence in court of a link between the dropping of fleas on Ningbo and the outbreak of bubonic plague a few days later.

The incubation period of plague is normally seven to ten days, but Huang said the fleas had been infected with a more toxic form of plague. He added that the fleas were not native to the area. "Only Unit 731 was capable of making such an intensified bacterium," Huang told the court.

Unit 731 ran Japan's biological warfare programme and had among its ranks some of Japan's top doctors and bacteriologists. The unit experimented on Chinese civilians and prisoners of war in a lab complex near Harbin in the north of China, which was then under Japanese control (New Scientist, 25 February 1995, p 12).

Peter Hadfield

SOURCE: New Scientist 3rd February 2001