Possibly HepA & HepE
Hepa & hepe are contagious by fecal-oral route, meaning a tiny bit of poop has to go from one person into another's mouth.
(farting) that includes "more" than just gas, can send enough poop by way of underwear or by way of hands to transmit hepa & hepe. This is a reason why health departments post warnings when a restaurant employee has hepa. The odor does not contain virus