A case cluster of variant Creutzfeldt-Jakob disease linked to the Kingdom of Saudi Arabia

Abstract

As of mid-2016, 231 cases of variant Creutzfeldt-Jakob disease—the human form of a prion disease of cattle, bovine spongiform encephalopathy—have been reported from 12 countries. With few exceptions, the affected individuals had histories of extended residence in the UK or other Western European countries during the period (1980–96) of maximum global risk for human exposure to bovine spongiform encephalopathy. However, the possibility remains that other geographic foci of human infection exist, identification of which may help to foreshadow the future of the epidemic. We report results of a quantitative analysis of country-specific relative risks of infection for three individuals diagnosed with variant Creutzfeldt-Jakob disease in the USA and Canada. All were born and raised in Saudi Arabia, but had histories of residence and travel in other countries. To calculate country-specific relative probabilities of infection, we aligned each patient’s life history with published estimates of probability distributions of incubation period and age at infection parameters from a UK cohort of 171 variant Creutzfeldt-Jakob disease cases. The distributions were then partitioned into probability density fractions according to time intervals of the patient’s residence and travel history, and the density fractions were combined by country. This calculation was performed for incubation period alone, age at infection alone, and jointly for incubation and age at infection. Country-specific fractions were normalized either to the total density between the individual’s dates of birth and symptom onset (‘lifetime’), or to that between 1980 and 1996, for a total of six combinations of parameter and interval. The country-specific relative probability of infection for Saudi Arabia clearly ranked highest under each of the six combinations of parameter × interval for Patients 1 and 2, with values ranging from 0.572 to 0.998, respectively, for Patient 2 (age at infection × lifetime) and Patient 1 (joint incubation and age at infection × 1980–96). For Patient 3, relative probabilities for Saudi Arabia were not as distinct from those for other countries using the lifetime interval: 0.394, 0.360 and 0.378, respectively, for incubation period, age at infection and jointly for incubation and age at infection. However, for this patient Saudi Arabia clearly ranked highest within the 1980–96 period: 0.859, 0.871 and 0.865, respectively, for incubation period, age at infection and jointly for incubation and age at infection. These findings support the hypothesis that human infection with bovine spongiform encephalopathy occurred in Saudi Arabia.

Clinical Laboratory Tests Used To Aid in Diagnosis of Human Prion Disease

“…vCJD is transmitted by ingestion of infected meat contaminated with BSE. As of 2016, there have been a total of 231 recognized cases of vCJD worldwide, mostly from the United Kingdom and other European countries (10). There have been four reported cases of vCJD in the United States (11), and all four patients were likely exposed to the prions in another country: two in the United Kingdom, one Saudi Arabia, and one in either a middle eastern or eastern European country.…”

Geographic exposure risk of variant Creutzfeldt‐Jakob disease in US blood donors: a risk‐ranking model to evaluate alternative donor‐deferral policies

“…We generally followed the UK convention of assigning a case to the United Kingdom when an individual had resided there for more than 6 months during the period from 1980 to 1996 . Other exceptions included a few vCJD cases attributed to nonreporting countries by US or Canadian authorities because of the individual's history of residence at the time of most probable infection based on the most plausible incubation period . The attributions of vCJD cases by country are summarized in Table (column: “No.…”

The importance of ongoing international surveillance for Creutzfeldt–Jakob disease

“…Spain had the third highest number of vCJD cases (five), three of which arose in a region with substantial rates of BSE in farmed cattle 147 . vCJD was also detected in nations that did not import British beef or have substantial rates of BSE, including Japan and the USA, and arose in individuals who had either spent time in the UK or in nations that imported British beef (such as Saudi Arabia) 148 . One individual in the USA was found to have vCJD in 2015 and had not spent time in the UK; this individual was thought to have been exposed prior to emigration to the US, presumably while living in Kuwait or Russia, nations known to have imported British beef 27 .…”