Diseases are spread easier through the rectum. But, when aids first came out ( and some people still feel this way) it was blamed on the gay community. Some people just continue to think that way, because they are small minded. But anyone is at risk for aids.
Family planning does not do a blood test unless they are testing you for aids (which you have to request, or agree to and sign a release) or if you have specific symptoms of something that would require bloodwork. I have gone to family planning for ten years and they have never taken my blood. You cannot legally test for aids without permission, so if you do not want or need that test, then they will not do it.