Iatrogenic CJD

What were the sources?

Two accounted for nearly all of them. A review published in 2012 counted 469 cases worldwide across all routes.

Growth hormone made from the pituitary glands of people who had died, used to treat children who were not growing, caused 226 cases. France had 119, the UK 65 and the United States 29. The UK used it between 1958 and 1985, and since then growth hormone has been made artificially.

Grafts of dura mater, the tough membrane covering the brain, used in some brain and spine operations, caused 228 cases. Japan accounted for 142 of those.

The remaining cases were very few: 4 from gonadotrophin, a fertility hormone also made from human tissue, 4 from neurosurgical instruments, 3 from blood for transfusion, 2 from stereotactic EEG needles used inside the brain, and 2 from corneal transplants.

CDC counts 6 CJD cases caused by contaminated surgical or medical equipment and notes that none has been reported since 1976, after decontamination procedures were changed.

Why did it take so long to notice?

Because the time between exposure and the first symptoms can be very long. In the growth hormone cases it averaged 17 years and ranged from 5 to 42 years. For dura mater grafts the average was 12 years, with a range of just over 1 year to 30 years. The cases that came from instruments appeared much sooner, within about 1 to 2 years.

CDC notes that growth hormone cases are still being identified roughly 50 years after the exposure. That is why these cases continue to appear occasionally even though the products were withdrawn long ago.

Are these routes closed now?

The authors of the 2012 review described the iatrogenic era as having nearly closed, with only occasional cases of very long incubation still appearing, and said no new sources had been identified. They recommended keeping the current precautions in place, including donor deferral and prion reduction steps for instruments and biological products.

Those precautions are why hospitals use special cleaning or single-use rules for a few kinds of surgery, and why some people cannot give blood, tissues or organs. In the European rules, people who received a cornea or dura mater graft, people treated with medicines made from human pituitary glands and people with a family history that puts them at risk of prion disease are permanently deferred from blood donation. The rules for tissue and cell donation are wider and also cover anyone diagnosed with CJD or variant CJD and anyone with a history of rapidly progressive dementia.

Variant CJD, which came from beef rather than from medical treatment, has also been passed on by blood transfusion in the UK on five occasions. Variant CJD covers that separately.

My relative had surgery. Should we be worried?

This is the question most people arrive with, and it is worth separating from the history above.

The products that caused most cases are no longer used. Pituitary growth hormone has been replaced by a manufactured version, and human dura mater grafting has been stopped or replaced in the countries that reported cases. Decontamination practice for surgical instruments changed in the 1970s, and no instrument-related case has been reported since 1976.

Nobody can tell you about one particular operation from a page, and nothing here is advice about a specific person. If someone in your family is worried about a past procedure, the surgical or neurological team who hold the records is the place to ask, and the national CJD surveillance centre for your country can be approached through them.

Where next?

Iatrogenic CJD: more detail is the clinical version, with the full route-by-route figures, and iatrogenic CJD for researchers the scientific one. How common is prion disease sets these cases against the other forms, and kuru is the other acquired human prion disease.

If someone is ill now, how prion disease is diagnosed and what to expect are the practical pages, and support groups lists people who can talk with you.