The most frequent of the latter include acquired forms secondary to injections of human cadaveric pituitary-derived growth hormone and the new variant of CJD--probably related to bovine spongiform encephalopathy.
France, involved for a long time in the epidemiological surveillance of transmissible spongiform encephalopathy (TSE), created a national network of surveillance in 1991, because of the description of the first cases of Creutzfeldt-Jakob disease (CJD) linked to a treatment by growth hormone of human origin and the observation of cases of cats infected with the agent of the bovine spongiform encephalopathy in the United Kingdom (UK).