Editorial: Investigation needed into wartime clinical trials on leprosy patients in Japan

The reality of the damage suffered by leprosy patients who fell victim to Japanese government-led human rights violations through its isolation policy has been uncovered. It has come to light that medical experiments were conducted on patients at National Sanatorium Kikuchi Keifuen in Kumamoto Prefecture during and after the Pacific War, with many residents being administered a drug that was still in the development process.

Despite confirming severe side effects and even fatal cases, these tests continued. The sanatorium investigated and analyzed stored documents and recently published a report.

The drug in question, “koha,” contained a photosensitive agent used in photography. It was believed to be effective in treating tuberculosis and also applicable in the treatment of Hansen’s disease, as both illnesses share similar pathogens. The sanatorium director at the time was actively involved in the trials.

Initially, one-third of the Kikuchi Keifuen residents participated, and the drug was given to a total of 472 people, including a 6-year-old child. Various methods of administration were tried, such as oral intake, topical application and injection, with varying dosages and intervals. Participants reported severe headaches, nausea and body aches. Nine people died, with the drug suspected to have caused two of these deaths.

Nevertheless, the tests were not halted. The remaining documents contained physicians’ observations that appeared to have downplayed the side effects.

What cannot be overlooked is the fact that residents were unable to refuse participation in the trials. Isolated from the outside world due to the government’s policy, they had no choice but to obey the director and other officials. Some testified that they “lied about feeling the effects of the drug.”

This violates medical ethics, which emphasizes respect for patients’ rights. Participation in the tests was for the most part compulsory, and authorities cannot avoid criticism that it was essentially a human experiment.

The context of the times also played a role. Amid the demand for improved health and physical strength to support the war effort, these trials were part of the army’s research.

While Kikuchi Keifuen says it will continue to analyze the documents, discussions involving medical and pharmaceutical experts are essential. There are records indicating that similar tests were conducted in other leprosy sanatoriums, and the government should lead an investigation.

The isolation policy continued until its legal basis was abolished in 1996. Prejudice and discrimination against former leprosy patients still persist deeply in society. The examination into the history of errors related to Hansen’s disease must continue to produce lessons from those mistakes.