01Why study this case — when "the operation that heals" carries the disease

The CJD drug-disaster case was not about drug interactions or a toxic solvent. Its cause was a medical material implanted in the body during surgery. In neurosurgery, when the dura mater (the membrane covering the brain) was damaged, human dried dura mater was used to repair it — and it carried Creutzfeldt–Jakob disease (CJD), an untreatable, fatal disease of the brain.

The patient underwent surgery to treat another condition. That very surgery, after a latency of more than a decade, brought a disease that leads with certainty to death. And the cause was neither bacterium nor virus but a prion — an abnormal protein that the standard sterilization of the day could not inactivate. Japan recorded the largest number of patients in the world for dura-mater-associated CJD. This piece traces why the harm was concentrated in Japan, and why stopping it came so late.

02What human dried dura mater was — the product called Lyodura

The cause was a product made by the German firm B. Braun, called "Lyodura." It was a human-derived tissue material, made by harvesting dura mater from deceased donors and drying and processing it. As an easy-to-handle, readily available material for suturing and patching the dura in neurosurgery, it was used widely around the world — and in Japan — from the 1970s.

The problem lay in its manufacturing. Dura mater from multiple donors could be processed together, so that if even one donor had been infected with CJD, the same product lot could be broadly contaminated. And the sterilization of the day (gamma irradiation and the like), effective against bacteria and viruses, did not work against prions.

03Prions — the "abnormal protein" that cannot be sterilized

The cause of CJD is neither virus nor bacterium. It is a prion — a protein folded into an abnormal three-dimensional shape. Because prions carry no genes (no nucleic acid), they resist ordinary heat, disinfection, and radiation. They accumulate in the brain, converting normal proteins into the abnormal form one after another and destroying nerve cells.

Once infected, a patient shows rapidly progressive dementia, myoclonus (involuntary jerks), and ataxia, and dies within roughly one to two years of onset. There is still no fundamental cure. And the latency is very long: from dura-mater grafting to onset averaged more than 10 years, exceeding 20 years in some cases.

The blind spot of the time: In the 1970s and 1980s, the nature of prions was not well understood. The common sense that "if it is sterilized, it is safe" — built around bacteria and viruses — did not hold for prions. A known safeguard was applied to an unknown risk — that is the scientific backdrop of this case.

04The scale of harm — Japan, the world's largest

140+Japanese dura-related CJD patients (reported)
world's mostJapan's share of dura-mater CJD
10+ yrsmean latency, graft to onset
1997Japan halts use of human dried dura

The great majority of CJD cases from human dried dura mater reported worldwide were concentrated in Japan. More than 140 patients were confirmed there — a number that stands out globally for dura-related CJD. Why the concentration in Japan? Because Lyodura was used especially widely there, and its use continued even after the danger had been flagged.

Most patients were people who had needed dura repair in surgery for brain tumors, head injury, or epilepsy. The operation succeeded and the original disease was treated. But years to a decade or more later, an unexplained, rapid cognitive decline began; they were diagnosed with CJD, and they died.

05The 1987 warning — the danger was known

The warning signs had appeared early. In 1987, the U.S. CDC reported a case of CJD in a patient who had received a human dried dura mater graft. That same year, the manufacturer B. Braun changed its production process (adding an alkaline treatment, among other steps) to inactivate prions. In other words, by 1987 it was beginning to be recognized worldwide that "this product carries a risk of transmitting CJD."

In Japan, however, the response lagged. Older product made before the process change, and product whose risk had been flagged, remained in use, and the Ministry of Health (as it then was) did not officially halt the use of human dried dura mater until 1997 — roughly ten years after the first warning. During that decade of delay, the harm grew.

06The same structure as the HIV case — a repeat of "non-action"

From the 1987 warning to the 1997 halt — this structure of delay is strikingly similar to the HIV-tainted blood case unfolding at almost the same time.

Both the HIV and CJD cases point their lesson the same way: "Can you act while still in doubt?" The longer one waits for conclusive evidence, the more the harm accumulates with biological products.

07Litigation and settlement — the state's responsibility acknowledged

Victims and bereaved families sued the state (the Ministry of Health), the importer-distributor, and the manufacturer (the CJD litigation, in the Otsu and Tokyo district courts and elsewhere). After a long trial, a settlement was reached in 2002. The state acknowledged responsibility for the delay in responding after the danger became known, and promised an apology and permanent relief for victims.

The settlement was not merely a monetary resolution. It pressed the state to answer, as a matter of institutional design, the question: "How far does the state bear a duty to manage the infection risk of biological products?"

08Four lessons that remain today

Lesson 1 — Known safeguards may not work against unknown risks

The premise "if it is sterilized, it is safe" was correct for bacteria and viruses but not for prions. New materials and new technologies can carry risk in forms not yet known. The dangerous assumption is precisely that an existing safeguard "must be working." This lesson applies directly to today's frontier medicine — regenerative therapy, cell- and tissue-engineered products, gene therapy.

Lesson 2 — Human-derived materials are inseparable from infection risk

Cadaveric dura mater, human blood, human cells — materials derived from people can carry whatever pathogen the donor harbored straight to the recipient. That is exactly why managing provenance (which donor), tracing lots (where it was used), and reporting infections are indispensable. This reckoning produced, in Japan's 2002 reform, the legal category of "biological products" with its strict traceability and infection-reporting system.

Lesson 3 — Delay in "stopping when in doubt" doubles the harm

From the 1987 warning to the 1997 halt was about ten years, and harm piled up in between. The cost of waiting for conclusive evidence is especially high for diseases with long latency. By the time the evidence is complete, many people have already finished being exposed. This case shows the weight of the precautionary principle — "when in doubt, stop."

Lesson 4 — Failures of the same structure recur in another product

The HIV and CJD cases, different in their causative agents, were identical in structure: danger flagged abroad, slow domestic response, omission enlarging the harm. The lesson supposedly learned from one drug disaster was not applied to another product. Here lies the importance of studying the "structure," not the individual incident.

09Connections to other chapters

The CJD case connects to other chapters of this site as follows.

In closing

The patients underwent brain surgery — to treat a tumor or an injury. The operation succeeded. But a single sheet of human dried dura mater, used to repair the damaged membrane, carried after more than a decade of silence an untreatable disease.

The cause was an abnormal protein that cannot be sterilized. The danger had been shown in 1987. Yet use stopped only in 1997. This decade-long structure of delay overlaps, eerily, with the HIV case of the same era. An unknown risk was assumed safe by known common sense; even as signs of danger appeared, conclusive proof was awaited, and stopping came too late — and the price was paid by people who had only tried to treat another illness.

Anyone in modern pharma or medicine who handles human- or biologically-derived products asks, always: "Does this source hide an infection risk we do not yet know?" The strict tracing and reporting system for biological products stands on this country's experience of the world's largest dura-mater CJD disaster.