You CAN get STDs via saliva. Oral herpes can containate via saliva. Herpes can also spread if left on an inanimate object. Herpetic Whitlock happens when herpes infects medical workers on the hands when the herpes reaches under the gloves.
Depending on the amount, if any, blood that is in her saliva - there can be a chance you can catch other diseases.
But, the occurances are rare. In reality, HIV is a very hard disease to contract. The virus does is very fragile, and cannot survive outside the body for very long.
Any advice given to you on the furom will never replace information you'll receive from your physician. The best way to ease any worries is to get tested.
Ignorance maybe bliss...but...is bliss worth your health?