Following retinitis, the most prevalent clinical manifestations are the following: colitis(in the US, 5–10% of HIV patients with low CD4 lymphocyte counts were affected by enterocolitis prior to the availability of HAART therapy [24]), esophagitis (most commonly due to co-infection with either herpes simplex virus or Candida albicans), pneumonitis, encephalitis, hepatitis, and adrenalitis [25]. Here, CD4 is linked to retinitis.