a very rare virus called Merkel cell polyomavirus that can lead to an aggressive form of skin cancer.

tl;dr hepatitis b and c, h. pylori (stomach bacteria), papilloma, one of the herpes viruses and hiv (all in common - long untreated infections that people may not notice (or suppressed via therapy), although article doesn't and cannot extrapolate that, article suggests vaccinations for viruses and testing for bacteria)

this is great news!

You don't say.