laser treatments, and topical therapy with either prescription medications such as imiquimod
or over the counter
medications such as salacetic acid (the
OTC preparations are, typically, less effective than therapy performed in the doctor's office or with prescription meds.
As for your GF, she may or may not have them and, since the lesions are typically painless, if she does, may not know that she has them or what they are. Other than visual inspection, there are no recommended tests for MC.