I don't see the harm in gagging anybody, as long as their airway isn't restricted.

In that vein, there's always Gerstmann-Sträussler-Scheinker syndrome, but it's familial, and even more rare than Kuru. So is the fatal insomnia. It's not something that comes up in a usual family medical screening, but worth looking into.

The laughter without syncope side effects is notable, which makes me believe Kuru - pathologic uncontrollable laughter. While these infections are fatal and without known treatment, prions themselves can be reverted with exposure to intense heat - nearly three hundred degrees Fahrenheit if memory serves - for twenty minutes or so. It would kill a human to incubate a fever of even half that intensity.