Latent toxoplasmosis is literally insidious, hidden inside body fat cells where antibiotics won't reach and only occasionally it gets out to infect more cells. So one round is not enough, you have to take antibiotics for years until all the infected cells die.
It sounds a lot like the explanation for chronic Lyme disease (except with nerve tissue and not fat cells), which is apparently still quite controversial despite having lots of anecdotal evidence to support it.
Also if the parasite is hiding in your fat cells, does that also mean that you can't detect it in a blood test?
Hmm. I wonder if there is an antibiotic prodrug that would mimic glucose enough for it to be recognised by beta cells, get metabolised and release the antibiotic payload inside a fat cell.