Multiple Mosaic viruses affect desert roses. Just glancing online the two biggies are tabacco mosaic and cucumber mosaic. Those viruses spread VERY easily to many plants. Discard the plant and keep a careful eye on the rest of them.
Tabacco mosaic in particular is often spread by someone smoking raw tabacco (like rolling their own). This is a likely vector for the initial infection in a greenhouse. Don't buy from them again.
edit: just in case, wash your hands between handling plants and isolate/sterilize your tools.
