Following a case of prion disease that was discovered in a former lab worker, five French public research institutions announced this week a three month moratorium on prion studies.The case could be linked to laboratory exposure. It would be the second such case in France. Another lab worker died from prion disease in France at 33 years old. Nine years ago, she had accidentally bitten her thumb with forceps that were used to remove frozen slices of infected humanized mouse brains.Prions and diseasesPrions are misfolded and misshapen forms normal proteins called prion protein, which can be found in both human and animal cells. Although it is not clear what prion proteins do in normal circumstances, they are easily found in the brain of humans. A misfolded prions can cause damage to normal prion proteins, leading them to also misfold, clump together and corrupt others. The brain tissue is eventually damaged as a result of the corruption that ripples through it. This gives the brain a sponge-like appearance, and is why prion diseases (also known as transmissible spongiformencephalopathies or TSEs) are so common.TSEs may manifest as rapidly developing dementia, pain nerve damage, confusion and psychiatric symptoms. They can also cause difficulty speaking and moving. TSEs are not treatable. They can progress quickly and often lead to death.Creutzfeldt Jakob disease (CJD) is the most common form of TSE in humans. There are two types: "classic" or "variant." One in a million people in the US suffer from the classic form. Patients usually die within one year. The disease is sporadic in about 85 percent of the classic CJD victims. This means that there is no clear explanation for the protein misfolding. About 5 to 15% of cases are linked to CJD in their families. Classic CJD may also be possible in rare cases. This is usually done through prion-contaminated medical procedures such as a corneal transplant.AdvertisementVariant CJD is an infectious type and is often linked to bovine spongiform, or "mad cow", disease. Variant CJD can be contracted by eating prion-contaminated meat. This was the case during a large outbreak in BSE in cattle and variant CJD in people living in the United Kingdom in the 1980s and 1990s. Variant CJD can also be contracted from prion-infected wounds. Prions may also spread via aerosols. At least, this is what researchers have proven in mice. Variant CJD can incubate for about 10 years after an exposure. This means that symptoms appear around a decade after the prion infection.milie JaumainIt is important to note that the clinical and pathological characteristics of both variant and classic forms CJD are distinct. One thing is that classic CJD is more common in older people (median death age is 68), while variant CJD is more common in younger adults (median death age is 28). Classic CJD can cause memory problems and confusion. Variant CJD can lead to psychiatric symptoms or nerve damage.The 2019 prion illness infected the young laboratory worker, milie Jaumain, was clearly caused by Variant CJD. Jaumain, 24, was working in France's National Research Institute for Agriculture, Food and Environment when she fatally stabbed her thumb. She had been wearing latex gloves and was able to draw blood. Armel Houel, her widower, said that Milie began to worry about the accident immediately after it happened and she mentioned it to all doctors.A case report of Jaumain's disease and death published in New England Journal of Medicine last years states that she first experienced symptoms in November 2017, approximately 7.5 years after her accident. She first felt burning pains in her neck and right shoulder. The pain grew over six months and eventually spread to her right side. She became anxious, depressed, and experienced visual hallucinations and memory impairment in January 2019. Her right side had stiffened her muscles. Jaumain established an association to ensure lab safety. She was diagnosed with variant CJD on April 2019. Before her death in June 2019, she lost the ability of moving and speaking. The variant CJD diagnosis was confirmed by postmortem analysis in the NEJM case file.AdvertisementResearchers are not able to rule out the possibility Jaumain may have contracted variant CJD from eating contaminated meat. The NEJM report's authors noted that Jaumain was the only person to have developed variant CJD from eating contaminated meat. This is despite the fact that it has been reported before in France. According to the authors, there was no risk of variant CJD occurring in France in 2019.Lab safetyThey also point out that occupational cases of variant CJD have been reported. The authors stated that the last known case of variant CJD in Italy was a 2016 death from BSE-infected brain tissue. However, further investigation revealed no laboratory accident.The moratorium on this week's French case is still in place. The research institutions announced the moratorium in a joint statement. They said it wasn't known yet if the former researcher who worked at the INRAE had classic or variant CJD.The joint statement released Tuesday reads: "The suspension period in effect as of today will allow it to study the possibility that there is a connection between the observed case, and the person’s former professional activities and adapt, if required, the preventive actions in force at the research laboratories."Science magazine reports that Jaumain's family filed both criminal and administrative charges against the INRAE. According to the magazine's reporter, Jaumain's family lawyer stated that she was not properly trained to handle dangerous prions safely, didn’t wear surgical gloves or metal mesh and didn’t immediately soak her thumb in bleach as the lawyer suggested.It is not easy to decontaminate prion. The World Health Organization suggests that you decontaminate waste materials by first soaking them in bleach for at least an hour and then placing them in an autoclave (a steamer-and-pressure-based sterilization machine) at 121 Celsius (250 F) for one hour. The WHO recommends that people puncture skin with a needle by encouraging bleeding and then washing the area with soap and water.Science reported that 17 other lab accidents involving prions were identified by French investigators. Five of these involved cuts or stabs. In light of Jaumains' death, some labs claimed they had increased safety by using less-sharp tools than metal and wearing cut-resistant gloves.
