I have an elder brother who suffers from AIDS. Am I obligated to inform the girl I wish to marry of my brother's illness? Since I intend to conceal this matter; will I be blameworthy or deceptive for concealing the matter? I am well and AIDS free.

If the case is as mentioned in the question, you are not legally obligated to inform your fiancée or her family of your brother's illness. You will not be blameworthy or deceptive for concealing the matter from them.

Allah Almighty knows best.