Brief Answer:
Very less risk for infection during asymptomatic phases but it is not Zero!

Detailed Answer:
Hello. Thank you for writing to us

I have read your question and I have noted your concern.

Hsv 2 usually infects genital mucosa. Therefore, the infection can be transmitted to oral mucosa by performing oral sex on an Hsv 2 infected individual, however, the risk of acquiring infection through oral sex is much less during an asymptomatic phase as compared to the risk during a clinically evident episode of genital herpes. There is no definite rsk value or figure, for transmission during asymptomatic phases. Asymptomatic viral shedding is not a continuous low level shedding as is commonly thought, rather in asymptomatic Hsv infection shedding is intermittent and occurs on only 10% of days. Moreover, a person who has an old infection with Hsv 2 and no recent recurrences is less likely to be infectious as compared to someone who has a recently acquired infection Or has had a recent recurrence of Hsv 2. In both these scenarios asymptomatic viral shedding is likely to be much higher and frequent as compared to that in an old infection Or no recent history of a recurrence.
Again, though Hsv 2 can cause oral infection/ herpes (oral herpes is more commonly caused by Hsv 1), the infections is less likely to be passed on during clinically asymptomatic phases, specially if someone who has never had an outbreak in or around oral mucosa. This is because even if the infection exists there, it is likely to be much less contagious.
To summarise, there is a very low risk from oral sex during asymptomatic phases but having said that the risk is not Zero. There is no defined value for this low risk because most infected individuals don't even know that they have the infection and hence don't know where and when they acquired it from.
To be sure, you may take a blood test for herpes (ELISA for Hsv 1 and 2) at 12-16 weeks and that would be conclusive.

Regards

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