ABOVE: Prion protein (shown in red) aggregating inside mouse neurons.

On Tuesday (July 27), five public research institutions in France announced they will suspend research on prions for three months. According to their joint press release, the decision was spurred by a case of Creutzfeldt-Jakob disease (CJD) in someone who may have been exposed to prions in a research lab.

According to ScienceCJD is the most common prion disease in humans. Prions are infectious misfolded proteins that cause other proteins to misfold and aggregate in the brain. The US Centers for Disease Control and Prevention defines two types of CJD: classical, which generally arises through spontaneous protein misfolding in the brain, and variant CJD (vCJD), which is believed to be caused by exposure to the same prion that causes mad cow disease. There are no vaccines or treatments for CJD, which is universally fatal. The type of CJD can only be diagnosed by examining postmortem brain tissue.

An anonymous source tells Science that the woman newly diagnosed with CJD used to work in a prion lab in Toulouse. The woman is still alive, and doctors don’t know if she has classical or variant CJD.

“This is the right way to go in the circumstances,” structural biologist Ronald Melki—who works at a prion lab jointly operated by two of the French institutions adopting the moratorium, The French Alternative Energies Commission and the French National Centre for Scientific Research—tells Science“It is always wise to ask questions about the whole working process when something goes wrong.” The other institutions participating in the moratorium are the French Agency for Food, Environmental and Occupational Health & Safety; the National Research Institute for Agriculture, Food and Environment (INRAE); and Inserm.

According to a Google Translate translation of the press release, the purpose of the research suspension is to allow time to investigate “the possibility of a link between the observed case and the person’s former professional activity,” as well as to adopt any necessary additional safety measures in prion labs.

If the investigation reveals that the patient contracted CJD from a lab, it wouldn’t be the first time this has happened in France.

In 2010, INRAE  lab worker Émilie Jaumain accidentally cut open her finger (through two layers of latex gloves) while cleaning lab equipment that was used with prion-containing samples, according to Gizmodo. Despite immediately alerting doctors to her potential exposure, Jaumain’s widower tells Science, she began developing painful symptoms in 2017 and severe psychological symptoms in early 2019, which led to a diagnosis of “probable vCJD.” She died the same year at the age of 33, and the diagnosis was confirmed after her death.

According to Science, independent safety reports found no safety violations in Jaumain’s lab, although Jaumain’s family’s lawyer tells Science there were precautions that could have saved the young researcher’s life, including wearing metal mesh gloves and soaking the cut finger in bleach. The safety reports did find at least 17 lab accidents within the last decade in French prion labs.

Neuroscientist Stéphane Haïk of the Paris Brain Institute tells Science that following Jaumain’s diagnosis, prion labs across the country began adopting additional safety procedures, such as using plastic scalpels and cut-resistant gloves.

“The occurrence of these harsh diseases in two of our scientific colleagues clearly affects the whole prion community,” Emmanuel Comoy, deputy director of CEA’s Unit of Prion Disorders and Related Infectious Agents, tells Science. The diagnoses “necessarily reinforces the awareness of the risk linked to these infectious agents,” he says.