Well, I know that there's virtually no chance of contracting oral herpes when no outbreak is present, but I understand that the majority of people who get herpes contract it when their partner has no signs of an outbreak. (70% according to that commercial, which is urged on by profits, but viral shedding is apparently more likely with HSV-2.)
You're more likely to spread HSV-2 when showing no signs: "According to Spruance, people with recurrent oral HSV-1 shed virus in their saliva about 5% of the time even when they show no symptoms. In the first year of infection, people with genital HSV-2 shed virus from the genital area about 6-10% of days when they show no symptoms, and less often over time. (Both of these figures reflect shedding as detected by viral culture.)" (http://www.herpes.com/hsv1-2.html)
That article goes more in depth and covers some more technicalities, but with statistics like that out there, not telling a partner about HSV-2 seems like a bigger deal, while the majority of people have HSV-1 anyway. It's mostly social stigma, though, they say.
no subject
You're more likely to spread HSV-2 when showing no signs: "According to Spruance, people with recurrent oral HSV-1 shed virus in their saliva about 5% of the time even when they show no symptoms. In the first year of infection, people with genital HSV-2 shed virus from the genital area about 6-10% of days when they show no symptoms, and less often over time. (Both of these figures reflect shedding as detected by viral culture.)" (http://www.herpes.com/hsv1-2.html)
That article goes more in depth and covers some more technicalities, but with statistics like that out there, not telling a partner about HSV-2 seems like a bigger deal, while the majority of people have HSV-1 anyway. It's mostly social stigma, though, they say.