have or had (Have you seen anyone who was having a scabies?)

[Mektok]

Dear teachers,
Hi, kindly assist me on these:

1. Have you seen anyone who was having a scabies? Does it mean that we had seen someone, somewhere within a certain time period in the past?
2. Have you seen anyone who has scabies? Does it mean that we are still in a certain period i.e. on going seeing someone with scabies?
3. Have you seen anyone who had scabies? Does it mean that we had seen someone with scabies in the past?
4.Have you seen anyone who had scabies?
Yes, I have.(I had seen someone)
The next question is, should I use who are or were they?

Regards,