My partner has strep throat and he thinks i could get it from swallowing his semen. is that possible.?

NO!: The "strep" of "strep throat" is streptococcus pyogenes or Group A strep and if you get it in the back of your throat and it is not treated it sometimes can lead to rheumatic heart disease. The "strep" that women sometimes have in their vaginas is Group B strep and if the infant picks it up going through the birth canal can either get a respiratory distress syndrome within the first few hours or

Not from that: Attack rates for group A strep with close contacts run as high 50-100%.It is passed in saliva, not semen, unless he has found a way to put his saliva there.Since normal adults mindlessly bring their fingers to their face (where the saliva can be) that action can pass it to any object they touch.You are more likely to get it from a kiss than genital contact.