Prion disease surveillance monitors the occurrence of prion diseases in the United States, but it also monitors for the emergence of vCJD and other potentially preventable new prion diseases, as well as for rare classic forms of prion diseases that are attributable to medical procedures. Prion disease surveillance also helps assess the efficacy of ongoing U.S. prevention measures.
CJD has been a NOTIFIABLE CONDITION in Texas since 1998, and it was likely under-reported and misdiagnosed for many years. For 15 years now, Texas has carried out enhanced surveillance (passive and active surveillance) for CJD, including sporadic, genetic/familial, and acquired (iatrogenic and variant) CJD. The success of this program is demonstrated by the identification and confirmation of sporadic (sCJD), genetic/familial (gCJD or fCJD) and variant CJD (vCJD), as well as other cases of human prion diseases such as Variably Protease Sensitive Prionopathy (VPSPr), Fatal Familial Insomnia (FFI), sporadic Fatal Insomnia (sFI), and Gerstmann-Sträussler-Scheinker (GSS) syndrome. From 2013-2022 Texas reported 337 confirmed, probable and possible cases, of which there were 308 sCJD, 20 fCJD, 1 vCJD, 1 FFI, 1 sFI, 1 GSS and 5 VPSPr cases. Texas also investigates higher priority suspect cases, such as suspect cases in persons <55 years old, as vCJD is rarely found in individuals >55 years old, reported suspected clusters, suspected iatrogenic cases, and suspected cases and cases with risk factors that could expose them to other prion diseases, such as chronic wasting disease of deer, elk, moose, and other cervids.
In 2014, Texas had the 4th US variant CJD case; the person was likely exposed to the infectious agent before moving to the United States. A full description of the case can be found at: https://stacks.cdc.gov/view/cdc/30921 or https://www.cdc.gov/eid/article/21/5/pdfs/14-2017.pdf.
Maheshwari A, Fischer M, Gambetti P, Parker A, Ram A, Soto C, Concha-Marambio L, Cohen Y, Belay ED, Maddox RA, Mead S, Goodman C, Kass JS, Schonberger LB,Hussein HM. Recent US Case of Variant Creutzfeldt-Jakob Disease-Global Implications. Emerg Infect Dis. 2015 May;21(5):750-9. doi:10.3201/eid2105.142017. PubMed PMID: 25897712; PubMed Central PMCID: PMC4412247.
The Centers for Disease Control and Prevention (CDC) reports a worldwide (including the United States) CJD incidence rate of approximately 1-2 cases per million population per year, and from 2016-2020 the average annual rate in the United States was approximately 5 cases per million population per year in persons 55 years of age or older.
In Texas, the average rate of deaths per million population due to CJD over the past 10 years (2013-2022) is 1.2 cases per million population per year. The average rate over two consecutive 5-year periods, 2013-2017 & 2018-2022, are 0.86 & 1.46 (cases per million population per year), respectively. There has been an increase in CJD cases over the last five years, and this can be attributed to several factors. The population of Texas is increasing but also aging, the availability of the RT-QuIC test (a new more sensitive ante-mortem CSF test) in 2015, as well as increased awareness of this testing, ability of physicians to order this CSF testing through commercial laboratories that forward specimens to the National Prion Disease Pathology Surveillance Center (NPDPSC), and confirmatory testing on brain tissue availability at NPDPSC, have all increased the surveillance for human prion diseases in Texas (increased testing, reporting, and antemortem diagnosis of CJD). The intensity of surveillance methods can also influence the reported incidence of CJD, and other prion diseases, and Texas conducts enhanced human prion disease surveillance. CDC also updated their criteria for classifying a CJD case, and this was implemented in Texas in 2019. The combination of a positive RT-QuIC CSF result with neuropsychiatric symptoms allows for decreased reliance on the presence of specific neurologic symptoms to classify a case of CJD. This has permitted the classification of CJD cases that previously may not have been counted. The change in the criteria for classifying a CJD case is evidence of the incorporation of scientific data into surveillance system approaches to count cases more accurately. In 2019, the number of CJD cases and the overall rate of CJD increased, however, in the majority of cases brain tissue was examined and there were no unusual findings. Also, only four of the 2019 cases were <55 years of age, all of whom had autopsies, and the brain tissue analysis did not reveal any unusual neuropathology. In 2020, the number of CJD cases and the overall rate of CJD decreased from 2019. This may be an influence from the COVID-19 pandemic and decreased seeking of healthcare; however, the rate did not significantly decrease like some other infectious diseases reported to public health. The number of cases that had brain tissue examined also decreased in 2020, and there was a higher number of cases in individuals <55 years of age. In 2020, nine cases were <55 years of age, of which three cases had brain tissue examined and there were no unusual findings, and six cases did not have brain tissue examined. In 2021, the number of CJD cases and overall rate of CJD increased but did not surpass the 2019 case count or rate. The percentage of cases that had brain tissue examined increased from 34% in 2020 to 44% in 2021, and none of the cases were <55 years of age. There was only one case in 2021 that was <55 years of age, and brain tissue was not examined. In 2022, the number of CJD cases and overall rate of CJD increased. The percentage of cases that had brain tissue examined decreased from 44% in 2021 to 38% in 2022, and three of the cases were <55 years of age with no unusual findings. There were four additional cases in 2022 that were <55 years of age, and brain tissue was not examined. Decreased confirmation of CJD via brain tissue analysis over the last several years could be an influence of the COVID-19 pandemic and response, increased trust by physicians in RT-QuIC CSF results and less reliance on autopsy results, decreased consent to autopsy by the patient or family, or other factors. Also, fluctuations in the rates of rare diseases, data obtained via CJD surveillance systems, and the demographics of cases is expected from year to year. The rate of CJD decreased from 2019 to 2020 and then increased from 2020 to 2021 and again from 2021 to 2022. However, small changes in case counts can lead to larger changes in rates, and with increased surveillance in Texas, increased awareness, and ease of ante-mortem testing using a better test, an average rate closer to 1.5 cases per million population per year may be more representative of CJD cases in Texas, which still falls within the worldwide rate of 1-2 cases per million population per year. There have also been efforts to increase autopsy rates, and the rate of cases that have brain tissue analysis will be monitored over time. All other CJD data will continue to be evaluated on an ongoing basis.