Do you test your cat for Leukimia/FIV or just vaccinate them against it?

What do you do if you cat has leukimia or FIV and  you want to adopt another cat who is healthy? I understand that the vaccine for leukimia is not a guarantee that they will not catch it and there is no vaccine for FIV, so what do you do if the cat you want to adopt has FIV? 

Thanks

There is a vaccine for FIV but most people who really know cats including vets recommend against it.  The vaccine will cause a cat to test positive for FIV the rest of their lives.  That would mean a death sentence if they are picked up by animal control and end up in a high kill situation.

If two cats get along well an FIV positive cat shouldn't be an issue.  It is passed by way of a deep bite.

FeLV is a different story.  If I had a kitty that was FeLV positive I would probably only adopt another FeLV positive cat.  There are some rescues that kind of reach out to FeLV positive cats and put them up for adoption.

thank you for replying. 
I will take him for testing and if negative, i will vaccinate him. Hopefully he has nothing.

He is negative. Yay.

Microchiped and vaccinated for leukimia,

They say I have to bring him back for another shot in 3 weeks. Isn't that too much too soon?

With many vaccinations there is an initial series.  After that it's a booster normally every 3 years.