I have never eaten any portions of anterior neck meat where I could potentially be getting paratracheal and retropharyngeal lymph nodes and thyroid gland. After all, consuming thyroid gland in hamburger can cause thyrotoxicosis.[/QUOTE
A properly prepared bone-in neck roast has none of that tissue.
Do you have a source describing transmission by direct contact from a cut? I thought all mad cow disease (BSE) and it's CJD variant in humans was from ingestion of contaminated meat from affected animals.
The US seems to be disease free in cattle. So if walking up the slaughter ramp is a reliable screening method maybe we just don't shoot stumbling deer or elk.
Apparently one of the tissues that may be a pathway also for peripheral innoculation getting to the CNS, is not only lymph nodes, but also sympathetic neural ganglia which run along the anterior spine. I am not a butcher, but know a little anatomy, and just personally don't feel comfortable enough I guess to avoid split hairs dissecting the neck & thorax in these regions in order to avoid these tissues. But to each his own.
Apparently, a whole lot of people ate "mad cow" infected meat, with relatively few identified related illnesses, but maybe some others were actually infected orally, though only developed subclinical aymptomatic disease/infections?...otherwise the oral transmission rate had to be very low I would think.
Here is one example of what I think you are asking about:
Human prion diseases: surgical lessons learned from iatrogenic prion transmission