Can the mono virus cause or trigger vasculitis?

Yes, absolutely.: Vasculitis wis well known to be associated with Epstein Barr Virus. That said there are other causes of rash with EBV. If you have vasculitis as a complication, you should be tested for other viral infections transmitted the same way such as HIV, Hepatitis C (unlikely) and you should also be immunized against Hep A once you recover. Follow up with your doctor and get treated if you haven't already