Objective: To summarize current information on the relation between CD4 counts and the risk of different HIV-related diseases.
Measurements and main results: MEDLINE search of English language articles between 1985 and 1996 using the medical subject heading (MeSH) term "CD4 lymphocyte count" and searches using key words of multiple HIV-related diseases were conducted. Some HIV-related diseases can be stratified to different CD4 count levels. Regardless of their CD4 count, HIV-infected patients are susceptible to sinusitis, Kaposi's sarcoma, community-acquired pneumonia, and oral hairy leukoplakia. In advanced HIV, when CD4 is below 200/mm3, Pneumocystis carinii pneumonia, toxoplasmosis, progressive multifocal leukoencephalopathy, Mycobacterium avium complex, molluscum contagiosum, and bacillary angiomatosis all increase in incidence. In very advanced HIV disease, when CD4 counts are below 50/mm3, patients are at risk of pseudomonas pneumonia, cytomegalovirus retinitis, central nervous system lymphoma, aspergillosis, and disseminated histoplasmosis.