CD4 and mitochondrial DNA depletion syndrome 4a: However, mortality remains highest among those with advanced HIV disease (AHD, in adults defined as CD4 count <200 cells/mm3 or World Health Organization [WHO] clinical stage 3 or 4 disease), at an increased risk for opportunistic infections (OIs), including tuberculosis (TB) and cryptococcal meningitis (CM) [2, 3].