If you have mono does that mean the last person kissed has mono?

Not necessarily. Mononucleosis (mono) is usually spread through contact with infected saliva, but not specifically through kissing. It can also be spread by sharing objects like drinks, utensils, or toothbrushes with someone carrying the virus. Additionally, mono can be transmitted through contact with blood, so sharing needles, razors, or other sharp objects can also spread the virus.