One of the biggest public health scare crises of the 1990s in the UK revolved around ‘Mad Cow Disease’. Bovine Spongiform Encephalopathy (BSE) is a neurodegenerative disease of cattle, which when to spread to humans is believed to result in variant Creutzfeldt–Jakob disease (sometimes abbreviated to CJD or vCJD), a rare and degenerative fatal brain disorder. Away from obvious concerns relating to the food chain and agricultural practices (and the subsequent change to regulations and industrial practices in those sectors), the BSE and CJD crises had a major impact in another area: surgical procedures.
The risk of transmission from cattle to humans is primarily through the food chain. Cattle are at risk of BSE if they are fed meat and bone meal containing remains of other cattle who developed the disease or came into contact with scrapie-infected sheep products. In turn, humans who eat the meat of such cattle can become carriers. The root cause in both cattle and humans are prions, which are misfolded proteins. These prions cause problems in the brain, resulting in psychiatric problems, behavioural changes and painful sensations. The length of time between exposure to these prions and the development of CJD symptoms has not been established; however, average life expectancy following the onset of symptoms is as little as thirteen months.
The transmission of CJD between humans can be also be traced to use the use of blood products and contaminated surgical instruments, leading to new guidance for healthcare professionals.
In terms of the overall risk to the population, people living in the UK before 1997 are considered to be at greater risk of developing vCJD in later life due to dietary exposure to BSE, as opposed to those born after this date; this is thanks to a change in agriculture processes, which were brought in after the initial crisis. There is evidence of abnormal prion protein in gut-related lymphoid tissue in roughly one in 2,000 of the older population, although there is no current way of identifying those affected or knowing the long-term implications for them; therefore, healthcare professionals are currently unable to test patients to see whether they are carrying prions that can cause CJD.
To address the risk of transmission in a healthcare and surgical environment, new healthcare guidance was established in the UK and elsewhere, given that CJD can result in fatality. Although the focus of the crisis was the UK, according to the World Health Organisation populations at risk also included those who had imported meat from other countries in which BSE was reported, including people who lived or worked in the UK before 1997. This accounts for incidents of CJD in France, Canada, the Republic of Ireland, Italy and the United States of America.
In the UK, NICE (National Institute for Health and Care Excellence) has published a complete set of guidance notes for healthcare professionals to reduce the risk of CJD. In terms of surgery and surgical instruments, the focus was on surgery where ‘high risk tissue’ was exposed, i.e. tissue that was thought to be highly susceptible to CJD. These include tissues involved with the brain, the retina or the optic nerve; medium risk procedures involving the tonsils, spleen, lymphoid tissue, spinal cord, anterior eye and peripheral nerves were also identified as a possible risk of CJD infection.
The overall guidance focussed on improving decontamination solutions or changes in decontamination practice on reusable surgical instruments, such as keeping instruments wet immediately after use until they are cleaned. Steps were also introduced that to ensure that instruments that come into contact with high-risk tissues do not move from one set of medical instruments to another.
Normal sterilisation procedures such as cooking, washing, and boiling do not destroy prions. Conventional sterilization and disinfection methods are therefore inadequate in reducing prion infectivity of contaminated instruments, and World Health Organisation recommendations for disinfection using bleach or sodium hydroxide are often impractical for routine decontamination.
In one instance, possible CJD exposure via infected surgical instruments was suspected at a large teaching hospital. Although CJD was later disproven, the subsequent investigation highlighted the difficulty in tracking infected surgical instruments and in protecting subsequent surgical patients from prion infection.
NICE concluded that supplementary surgical instruments that come into contact with high-risk tissues should either be single-use or should remain with the set to which they have been introduced.
Ultimately, one cannot completely eliminate the risk of the transmission of CJD between patients as reusable surgical instruments are used on multiple patients, and sterilisation procedures are not 100% effective. Those patients who have undergone high-risk procedures may have an increased risk of contracting CJD and could potentially transmit the disease via subsequent high-risk procedures. Using single-use instruments would prevent onward transmission and reduce the overall number of infections via interventional procedures.
Even though the incidence of CJD has declined, several hundred people have died from CJD acquired through healthcare worldwide. Transmission from re-used EEG needles or neurosurgical instruments have caused up to seven cases of CJD. The risk remains prevalent; in October 2018, the British Medical Journal reported on research that around one in 2,000 people in the UK may carry variant CJD proteins.
Aside from the risks to patient safety, the costs of treating those suffering from CJD is approximately £40,000 per patient, based on estimates provided by the Department of Health in the UK.
The scale of threat posed by CJD has receded but remains present, and it still has consequences for healthcare practitioners and surgical theatre staff around the world. It is therefore important that the use of appropriate surgical instruments remains at the forefront of their minds during procedures that pose a risk of CJD transmission. Indeed, the concerns around transmission of CJD in a surgical setting has led to the adoption of single-use surgical instruments.
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 ‘Patient safety and reduction of risk of transmission of Creutzfeldt–Jakob disease (CJD) via interventional procedures: Background’, NICE Interventional Procedures Guidance, November 2006 [accessed January 2019].
 ‘Iatrogenic Creutzfeldt-Jakob disease via surgical instruments’, Department of Neurosurgery, Baylor College of Medicine, Houston, TX, USA, 2013 [accessed January 2019].
 ‘Patient safety and reduction of risk of transmission of Creutzfeldt–Jakob disease (CJD) via interventional procedures: Evidence and interpretation’, NICE Interventional Procedures Guidance, November 2006 [accessed January 2019].