Yes, pretty sure, it is my speciality! It is a viral infection which is usually diagnosed based only on clinical appearance. Rarely we go for a swab to diagnose herps simplex virus. Theoretically, we can check for antibodies in the blood, but no one do that! it is unnecessary!
You are admissible to Canada even if you are diagnosed with herps. By the way, almost every one of us has got herps simplex before; and we have the latent virus in our tissues which becomes activated when our immunity drops-off. Usually it wouldn't last more than a week. It is a self-limited disease and it would often cure without any treatment unless the patient is immunocompromised.