Hiv is a disease in which the immune cells are destroyed. CD4 is a type of T cell which is an immune cell. Prophylaxis for super infections in HIV is based on the levels of CD4. Typically, the lower the CD4 cell counts, the more severe sickness the pt will have. HIV/AIDS pt doesn't have those typical viral or bacterial diseases per se, they have those super infections such as very rare bacterial or fungal diseases.
~Wonder Me!