Is there horizontal transmission of Creutzfeldt-Jakob disease?

Sporadic Creutzfeldt-Jakob disease (s-CJD) is a rare, fatal neurodegenerative disorder. Familial cases of Creutzfeldt-Jakob disease (f-CJD) due to mutations in the PRNP gene are even rarer around the world; however, in Israel there is a focus of f-CJD patients carrying the E200K mutation. As the number of CJD E200K carriers in Israel is high and increasing, transmission of CJD to normal people was suspected. If such transmission occurs, the incidence of s-CJD would be expected to increase as well, resulting in changes of the ratio of familial/sporadic cases.Using data from the National CJD Registry and official statistics on the Israeli population, we studied incidence rates of f-CJD and s-CJD for the period from 1985 to 2018 applying the Surveillance Epidemiology and End Results (SEER) statistical packet developed in the US National Cancer Institute.In total, 621 CJD patients (405 f-CJD and 216 s-CJD) cases are included in the registry. In the cohort of f-CJD patients, the mean age-adjusted annual incidence rate over the abovementioned period was 1.88 ± 0.09 (95% CI: 1.7-2.08) per 1,000,000. In the cohort of s-CJD patients, the mean age-adjusted incidence rate over the same period was 0.93 ± 0.06 (95% CI: 0.81-1.06) per 1,000,000 people. No significant time trends were found over the observation period in either s-CJD or f-CJD. The ratio f-CJD/s-CJD decreases over the observation period from 2.2 to 1.80.Israel has a high predominance of f-CJD compared to s-CJD. The mean incidence rate of s-CJD in Israel is similar to most countries. Between 1985 and 2018, the annual age-adjusted incidence rates for both forms of CJD remained stable. Thus, there is no evidence that CJD is transmitted from affected individuals to others.