Many of these individuals are likely to have had an “unmasking” IRIS, with evidence for more active inflammation in terms of higher CD4 counts, higher CSF white cell counts, and higher CSF protein levels, and meningitis could have been prevented by CD4 testing, reflex cryptococcal antigen screening and preemptive fluconazole at ART initiation [20–23]. This evidence concerns the gene CD4 and meningitis.