My girlfriend is just getting over mono, and I don’t know when it’s safe to kiss her again. I really don’t want to get what she had — it was awful.
Mono is called the kissing disease with some justification, since the virus causing it — the Epstein-Barr virus (EBV) — is often present in saliva. In all likelihood you have already had it, and still do.
EBV is a member of the herpes family of viruses. The family includes the two herpes viruses, the varicella-zoster virus that causes chickenpox, the EBV virus, and several others. One characteristic of all the viruses in this family is that they persist in a person’s body for life once the person has been infected. Several of them are very common in our society.
For example it is estimated that 90 percent of adults have been infected by the EBV virus, and are therefore carriers of it. Likewise, 80 percent of adults are thought to carry herpes I in the mouth, which causes fever blisters, and about 40 percent carry herpes II, the cause of most genital herpes.
It is estimated that carriers of EBV, who are 90 percent of the adult population, shed the virus in their saliva about 20 percent of the time. Therefor, on any given day, most of us have a one in five chance of shedding virus. We don’t feel sick when shedding, and there is no way to tell if we are doing it or not. You in fact probably gave your girlfriend the infection, assuming that you had only been kissing each other during the period before she became ill.
Because EBV is so common in adults, most people catch it when they are children, through hugging and kissing their parents. Children with EBV are often thought to have just another cold, with a bit of fever and swollen glands. It’s the unlucky few of us that make it to adolescence without getting infected who are susceptible to catching mono through kissing. As with many diseases which may be mild in childhood, adolescents or adults who catch EBV can have a much more severe and protracted disease, which is infectious mono.