I am worried because if I have to start a drug regime and they find out I am HIV poz can they fire me? It is a very small company but great people. I want to keep this from them as much as possible. I don't know exactly what do.

You can't be fired for having HIV--not legally, at least. If you have to take meds at work, take a note from your doc explaining that you need to take meds at work, but not including the names of the meds or the diagnosis. Don't offer the note, but have it on hand in case anyone from HR asks.

Allowing you to take meds at work would be a reasonable accommodation, a practice covered under the Americans with Disabilities Act.

There is NO situation that would require you to tell them you have HIV. You may need to tell them that you have a disability, which is true. But you don't have to identify it. Sometimes you have to identify the diagnosis to an insurer, but that's not the same thing as telling your employer.

Is there an on-site HR director? You should consider having a conversation with that person in which you identify yourself as a person with a disability who needs to take meds during work hours. If the HR director is a company manager who does HR and 45 other things, that might not be the best idea. Is anyone else at work living with a disability? How does that person manage? See what you can learn about how your employer treats disabled employees before you schedule a conversation.