A number of prion diseases affect humans, including Creutzfeldt-Jakob disease; 
most of these are due to genetic mutations in the affected individual and occur 
sporadically, but some result from transmission of prion proteins from external 
sources. Of the known animal prion diseases, only bovine spongiform 
encephalopathy prions have been shown to be transmissible from animals to humans 
under non-experimental conditions. Chronic wasting disease (CWD) is a prion 
disease that affects cervids (e.g., deer and elk) in North America and isolated 
populations in Korea and Europe. Systematic review methodology was used to 
identify, select, critically appraise and analyse data from relevant research. 
Studies were evaluated for adherence to good conduct based on their study design 
following the Cochrane collaboration's approach to grading the quality of 
evidence and the strength of recommendations (GRADE). Twenty-three studies were 
included after screening 800 citations from the literature search and evaluating 
78 full papers. Studies examined the transmissibility of CWD prions to humans 
using epidemiological study design, in vitro and in vivo experiments. Five 
epidemiological studies, two studies on macaques and seven studies on humanized 
transgenic mice provided no evidence to support the possibility of transmission 
of CWD prions to humans. Ongoing surveillance in the United States and Canada 
has not documented CWD transmission to humans. However, two studies on squirrel 
monkeys provided evidence that transmission of CWD prions resulting in prion 
disease is possible in these monkeys under experimental conditions and seven 
in vitro experiments provided evidence that CWD prions can convert human prion 
protein to a misfolded state. Therefore, future discovery of CWD transmission to 
humans cannot be entirely ruled out on the basis of current studies, 
particularly in the light of possible decades-long incubation periods for CWD 
prions in humans. It would be prudent to continue CWD research and epidemiologic 
surveillance, exercise caution when handling potentially contaminated material 
and explore CWD management opportunities.