Thank you for your comment. Yes. HSV-1 and VZV have been studied as risk factors for Parkinson's disease (PD) as well, but not to the extent of AD.

As far as I know, the main infectious agent implicated in PD is influenza actually, since it exhibits a tropism/preference to infect the substantia nigra in animal studies. Substantia nigra is the key brain region that's degenerating in PD.

That's quite pricey - I heard that healthcare in the U.S. is more expensive than in other countries.