Can a blood test be determined if a man has genital herpes?

Yes and no....: A blood test can tell whether someone is infected with herpes simplex virus type 1 (HSV1) and/or HSV2. It doesn't tell if genital or oral; that requires symptoms and/or testing of an outbreak for the virus. Most HSV1 is oral, some genital; almost all HSV2 is genital. The tests aren't perfect, but if you have symptoms that suggest GH or an infected partner, testing can be helpful.