| Bacteria | Disease | Notes |
| Mycobacterium avium-intracellulare | TB-like | Especially CD4 < 50 |
| Bartonella henselae | Bacillary angiomatosis | Superficial vascular proliferation |
| Virus | Disease | Notes |
| CMV | CMV retinitis, pneumonia | “Cotton-wool spots” on fundoscopic exam in retinitis, Cowdry type A intranuclear inclusion bodies |
| EBV | Oral hairy leukoplakia (OHL), Non-Hodgkin’s lymphoma | — |
| HPV | Squamous cell carcinoma | Anus or cervix |
| HHV-8 | Kaposi’s sarcoma | — |
| JC virus | Progressive multifocal leukoencephalopathy (PML) | White matter damage in CNS, demyelination |
| Fungi | Disease | Notes |
| Histoplasma capsulatum | Histoplasmosis (pneumonia), hepatosplenomegaly, fever | Disseminated disease only in immunocompromised |
| Candida albicans | Thrush, esophagitis | White plaque on oral mucosa |
| Cryptococcus neoformans | Meningitis, encephalitis | Most common meningitis in AIDS |
| Aspergillus fumigatus | Invasive aspergillosis | Pleuritic pain, hemoptysis |
| Pneumocystis jiroveci | “PCP” (“P. carinii” pneumonia) | Especially CD4 < 200 |
| Protozoa | Disease | Notes |
| CryptosporiDium | Diarrhea | Acid-fast cysts in stool |
| Toxoplasma gondii | Brain abscesses | Ring-enhancing lesions |
