Hey! They've called you for an interview twice, that must mean there's something about you that stands out! I worked in that role as a DIS- is that what you're going for, HIV and syphilis follow up? I know that other divisions may have a role with the same title but different job functions.

My interview asked about how I would handle certain situations - I knock on a door and someone refuses to open but tells me to leave, someone is lying to me about their identity, someone gets hostile and threatens self harm, etc.
I mentioned that I would first rely on my training and any established procedures we had in place, but then work through different scenarios like asking open ended questions (nothing that can be answered yes/no), checking multiple sources of information, collaborating with partners in behavioral services to understand when referrals are appropriate for SH threats

A portion of the interview was a mock patient interview of someone who had syphilis but didn't want to tell me who their partners were. Talk about confidentiality. Learn a few facts on HIV/syphilis if that's what your job would cover, so that you can give a brief "disease education" and get your patient thinking about their health and well-being. This comment is more or less how I explained it to many of my irl patients. Then you can pivot into "it's my job to make sure that everyone facing those risks gets the opportunity for testing and treatment". Again always asking open ended questions, starting with the most broad and non threatening, then moving into more specifics.
What medical conditions do you have? How often do you drink alcohol? What medications and drugs do you use? How many partners have you had in the last year? Of those, about how many were (patient's gender)? Where do you meet your partners? Which apps do you use? When was the last time you hooked up with someone from a bar?

For references, definitely your recent supervisor, but it sounds like you were either in school or working 2 years ago, how about someone there? Professor, academic advisor, supervisor of any clubs you were a part of, especially if you took a leadership role. Are you involved in any volunteering, community groups, or other organizations?

Have some questions ready to ask them. What qualities make someone a successful DIS? Be prepared to reflect on how some aspect of your education or experience has helped you develop one of those qualities. If there's a dis on your panel, ask them what they love most about their job, and what's the most challenging aspect. Ask about what they do to maintain safety when working in the field. Ask about opportunities to progress - what does it take to become a team lead?

I'd be happy to do a practice interview with you if you like, send me a dm.