Japanese Use of Plague during World War II

I’ve been reading Sheldon Harris’ Factories of Death: Japanese Biological Warfare, 1932-1945, and the American Cover-up. (Rev. ed, 2002), considered the definitive book on biological warfare in the Pacific theater during WWII. My primary interest is in Japanese research and use of plague in their biological warfare program.  Since this blog is, in part, a research tool, this post is a collection of notes taken specifically on the plague, though the book covers a much wider program. If you ever wondered why plague is a category A bioterrorism agent, what follows will go a long way in explaining.

Lt. Gen. Shiro Ishii (1892-1959) of Unit 731, the biological warfare unit of Imperial Japan.

Lt. Gen. Shiro Ishii was the primary organizer, promoter, and director of the Japanese biological warfare (BW) program. He was involved at all levels from pitch-man to the Japanese military and academia to personally supervising research on human subjects. He began his work research on the potential of biological weapons in the late 1920s.

One of Ishii’s first facilities was called the Zhong Ma Castle in Beiyinhe northern Manchuria. Initially, their test subjects were trouble makers among the Chinese population: criminals, communists, and other suspicious persons. Ishii began by focusing on plague, glanders, and anthrax. Subjects were injected with the pathogen and the course of their disease was monitored; all were extensively autopsied. (p. 33-34) There are numerous reports of autopsies being carried out on the unconscious, as in not yet dead.

In 1939 the stressed Japanese military allowed Ishii to send several BW attacks against Soviet forces in the Nomonhan region. Details of the mission refer to the contamination of water supplies with typhoid but plague, cholera, and dysentery affected both Japanese and Soviet troops during the campaign. Harris is unclear whether these were effects of biological weapons operations or naturally occurring outbreaks. (p. 97-98) In 1942 a Soviet defector to Germany claimed that Soviet biological weapons were field tested during combat in Mongolia (/Manchuria) and that there was a major plague epidemic at that time. (p. 98) With both sides attempting biological warfare and with the level of technology at the time, it is unlikely that it will be possible to unravel the outcome of either the Japanese or Soviet efforts.  The Japanese BW program was developed primarily with a future war against the Soviets in mind, as Japan planned to take land north of Manchuria. The intent of the BW program was to give Japan an advantage over the vast population and natural resources of China and the Soviet Union.

Shiro Ishii built an extensive network of facilities in China for the purposes of research and testing. Some details of these units in respect to plague activity follows:

  • Unit 731 was the primary unit under Ishii’s command based at his specially built facility at Ping Fan outside of Harbin, Manchuria. The scale of Ping Fan was enormous. Here Ishii built his dream facility complete with four boilers capable of producing one ton of  culture media each sterilized in fourteen autoclaves, ‘Ishii cultivators’ each capable of producing 30 kilograms of bacterial cell mass, and the capacity to maintain  plague, cholera, typhoid and paratyphoid, dysentery, anthrax, gas gangrene, tetanus, and glanders. Ping Fan was also equipped with the capacity to mass produce fleas and its own fleet of airplanes for experiments. (p. 69) After the war, Maj. Gen. Kawaashima Kiyochi boasted that Ping Fan could produce 300 kg of plague monthly in addition to other pathogens. (p. 69)
Manchuria, today split between Russia and China. (Public domain image from the CIA’s World Fact Book via Wikipedia Commons.)
  • Unit 731 conducted ‘field tests’ throughout northern and eastern China from late 1939 to 1942. They specialized in spreading pathogens by contaminated water and food. They tested cholera, typhoid, paratyphoid, and especially anthrax and plague. They were reported to start epidemics and then enter villages claiming to vaccinate against the epidemic, except that they would inject the pathogen instead. Their experiments involved introducing pathogens by unusual routes such as ‘vaccine’ injections including cholera bacteria. In a Soviet war crimes trial, testimony was given that Ishii’s forces handed out special chocolate bars laced with anthrax to Chinese school children “with unavoidable side effects”‘. (p. 99)
  • Unit 731  gave special attention to the plague, spreading plague infected rats widely throughout China and experimenting with spreading the plague through fomites like contaminated fountain pens or canes. When a full-scale epidemic broke out, Japanese soldiers would force an evacuation of the village and burn it to the ground. An American missionary Archie Crouch reported seeing Japanese planes drop odd bombs that spread what looked like wheat over the city of Ningbo and plague erupted just days later. Chinese officials tried to combat the plague with isolation, quarantine and burning the most infected part of the city but over 500 people died of the plague and other agents spread by Ishii’s forces. Outbreaks of plague continued in the region of Ningbo until as late as 1959 (p. 101-103).  The city of Quzhou was also subjected to bombs that scattered, soy beans and rags contaminated with plague, cholera, typhoid and possibly anthrax. Bacteriologist Qui Mingxuan lived in the city as a child and put the death toll for the six years after the first plague outbreak in 1940 at 50,000. Qui noted that there was no history of plague in Quzhou before 1940. (p. 102) In August 1942 plague was sprayed over the village of Congshan in the Zhejiang Province.  Rats began to die in droves two weeks later and over the next two months, 392 out of 1200 residents died of bubonic plague. (p. 103) For unexplained reasons, after 1942 Unit 731 stopped large field tests and began to concentrate on more direct human experimentation in controlled environments. Harris estimates that by the end of 1942, “the casualty count in the open tests surely fell into the six figure range” (p. 104).
  • Enough credible reports made their way out of China to convince the Allies that Japan was conducting biological warfare. (p. 100-103) In addition to reports coming out of China, American investigators found ampoules of cholera in Burma that locals reported were dropped from planes by the Japanese. In September 1944, Thailand also experienced a plague although there had been no recent plague activity in the area. The Thais and Americans both concluded that these outbreaks in Burma and Thailand were acts of biological warfare by Japan. (p. 226)
  • The facility at Nanking, operated by Unit Ei 1644 under the direction of Tomosada Masuda, was a mass production site for bacteria (cholera, typhus, and plague), rodents and vectors. Nanking specialized in flea production for plague experiments. It was also a training site for bacteriologists to conduct biological warfare, producing about  900  from 1941-1943 (p. 142-143)
  • Unit 100 in Changchun region worked on plague among other pathogens from 1940 to 1945. Although plague outbreaks had occurred in the region previously, several large suspicious outbreaks that took thousands of lives occurred from 1940 to the end of the war. Unit 100 used these outbreaks as cover for widespread experimentation on villagers.  Injecting slum dwellers with plague under the guise of vaccines against the plague was one of their notable practices. They then relocated about 5000 survivors and burned the slum to the ground. As the war was coming to a close, the order came to destroy all evidence, buildings, and people. None of the test subjects or Chinese workers escaped. Some of the infected animals were released into the countryside after the official surrender possibly triggering outbreaks of plague, anthrax, and glanders in 1946, 1947 and 1951. (p. 126-133)
  • At the Anda test facility in northern Manchuria, Chinese test subjects were tied to open air stakes and bombs containing either an anthrax slurry or plague-infected fleas were exploded around them in an attempt to infect them. There is some evidence that anthrax worked slightly better than the plague because the fleas did not handle the exploding bomb well (!). By 1944 they were working on developing means for spreading pneumonic plague and other respiratory pathogens. Fortunately, they were still unsuccessful by the end of the war. (p. 88-90) Ishii would later brag to US war dept. interrogators that he developed a porcelain bomb that successfully disseminated plague (p. 247).

At the beginning of the war, the American biological weapons program was the least developed of all the major combatants. The US military was eager to repair this deficit. American offensive and defensive biological warfare research began at Fort Detrick, Maryland, in 1942. The plague was one of many different pathogens worked on during the war. (p. 210) After the Japanese surrender, American officials were much more interested in extracting intelligence from cooperative Japanese researchers, including Shiro Ishii, than in pursuing justice for the Chinese or even American POWs that were victims of their experiments. To ensure cooperation Shiro Ishii was given immunity from prosecution and no one was ever brought to the war crimes trials in Tokyo for biological warfare.  I will leave issues of justice and the cover-up to journalists and political historians.

I do have to take issue with Harris’ assertion that Shiro Ishii was a good microbiologist. He may have been a good pitchman, organizer and military man but not necessarily a good biologist or physician.  First, I can’t accept that anyone racist enough to mentally justify this work was a competent biologist, much less a physician. Designing and carrying out these ‘experiments’ are the sign of an unstable mind. Methodologically,  ‘try absolutely everything you can think of and something might work’ is not good science, not even in wartime. Even if allied programs did similar things, it is still not good science. He thought more like an engineer than a biologist. The innovation that started his career and gained military attention was the development of a water filtration system to prevent cholera for the military. From a strategic point of view, biological weapons were incredibly risky in the 1940s before the discovery of penicillin and other effective antibiotics. The Japanese military actually had to reign them in out of fears of blow-back. Considering what the Japanese military was willing to do during World War II, this says a great deal.

4 thoughts on “Japanese Use of Plague during World War II

  1. Thanks for an informative article about this aspect of biological warfare. I had heard of Unit 731 and knew of their experiments on prisoners and the like (e. g. the frostbite experiments) but didn’t know that they had spread their experiments to villages and large populations. This is bone chilling.


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